Post on 03-Sep-2020
Management of Radioactive Residues from Mining, Mineral Processing, and other
NORM Related Activities
DRAFT SAFETY GUIDE
No. DS 459
New Safety Guide
Status: Draft prepared by the consultancy
meeting, 4-8 November 2013
This Review - March 2014
FOREWORD
by
Director General
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Contents
1. INTRODUCTION .................................................................................................................. 4
BACKGROUND.............................................................................................................................. 4 OBJECTIVES .................................................................................................................................. 7 SCOPE ............................................................................................................................................. 7 STRUCTURE .................................................................................................................................. 8
2. ADMINISTRATIVE, LEGAL AND REGULATORY FRAMEWORK ............................ 10
INTRODUCTION.......................................................................................................................... 10 NATIONAL POLICY AND STRATEGY .................................................................................... 10 RESPONSIBILITIES ..................................................................................................................... 13 MEMBER STATES ....................................................................................................................... 14 REGULATORY BODY ................................................................................................................ 15 OPERATOR ................................................................................................................................... 18 SCOPE OF REGULATORY CONTROL ..................................................................................... 19 GRADED APPROACH FOR IMPOSING CONTROL ................................................................ 23 SCREENING ASSESSMENTS ..................................................................................................... 24
3. PROTECTION OF PEOPLE AND THE ENVIRONMENT .............................................. 27
INTRODUCTION.......................................................................................................................... 27 GENERAL PRINCIPLES .............................................................................................................. 27 RADIATION PROTECTION ........................................................................................................ 28
4. GENERAL ASPECTS OF RESIDUE MANAGEMENT ................................................... 34
INTRODUCTION.......................................................................................................................... 34 INVENTORY OF PROCESSES GENERATING NORM RESIDUES ........................................ 35 CHARACTERIZATION AND SEGREGATION ......................................................................... 37 OPTIONS FOR RESIDUE MANAGEMENT .............................................................................. 37 REMEDIATION OF RESIDUE FACILITIES .............................................................................. 54
5. LIFE CYCLE MANAGEMENT OF NORM RESIDUES .................................................. 55
INTRODUCTION.......................................................................................................................... 55 SITING ........................................................................................................................................... 56 DESIGN AND CONSTRUCTION ................................................................................................ 57 OPERATION ................................................................................................................................. 70 CLOSURE ..................................................................................................................................... 76 REMOVAL OF REGULATORY CONTROL .............................................................................. 81 INSTITUTIONAL CONTROL...................................................................................................... 81
6. SAFETY ASSESSMENT AND SAFETY CASE ............................................................... 83
INTRODUCTION.......................................................................................................................... 83 GRADED APPROACH FOR SAFETY ASSESSMENT.............................................................. 84 SCOPE OF THE SAFETY ASSESSMENT .................................................................................. 86 CONDUCTING A SAFETY ASSESSMENT ............................................................................... 87 DOCUMENTATION OF SAFETY CASE AND SUPPORTING SAFETY ASSESSMENT ...... 93 PERIODIC SAFETY REVIEWS................................................................................................... 94
7. MANAGEMENT SYSTEMS .............................................................................................. 95
MANAGEMENT RESPONSIBILITY .......................................................................................... 96 RESOURCE MANAGEMENT ..................................................................................................... 97 PROCESS IMPLEMENTATION .................................................................................................. 98
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MEASUREMENT, ASSESSMENT AND IMPROVEMENT ...................................................... 99
8. MONITORING AND SURVEILLANCE .................................................................... 101
OVERVIEW OF MONITORING AND SURVEILLANCE ....................................................... 101 RESPONSIBILITIES OF THE OPERATOR AND REGULATORY BODY ............................ 102 OBJECTIVES AND DESIGN OF THE MONITORING ........................................................... 103
9. FINANCIAL ASSURANCE ........................................................................................ 106
REFERENCES ....................................................................................................................... 110
ANNEX I. ORIGIN AND CATEGORIZATION OF NORM RESIDUES ..................... 112
ANNEX II. REUSE AND RECYCLING OF NORM RESIDUES .................................. 115
ANNEX III. PRACTICAL TECHNIQUES FOR DETERMINING RADIONUCLIDE
ACTIVITY CONCENTRATIONS .............................................................................. 119
INTRODUCTION ...................................................................................................................... 119 SAMPLING OF MATERIAL ................................................................................................... 119 MEASUREMENT ACCURACY AND QUALITY ASSURANCE ....................................... 120 ANALYTICAL TECHNIQUES ............................................................................................... 120
1. INTRODUCTION
BACKGROUND
1.1 Radionuclides of natural origin are ubiquitous in the environment, and in some
geological formations have become sufficiently concentrated for the formations to be
exploited as uranium or thorium ores. The mining and processing of uranium and
thorium ores, including the management of the resulting residues, have long been
recognized as needing to be subject to regulatory control. However, significant
concentration of radionuclides of natural origin may also occur in other commercially
exploited minerals and/or in the residues from the processing of these minerals, where
the presence of such radionuclides is incidental and unwanted.
1.2 Residues are of particular importance in this regard, because the extraction
and processing of a mineral may have changed the properties of the raw material so as
to increase its potential radiological impact on workers, members of the public, or the
environment, for example by modifying the solubility, speciation or activity
concentration of the radioactive elements of concern. Until recently, relatively little
attention has been given to the possible need for regulatory control of radioactive
residues from mining and minerals processing other than those associated with
uranium or thorium extraction. As a result, residues from such operations, irrespective
of whether they are recycled, used in other applications or disposed of as waste, may
not have been subject to regulatory control in the past, even though they may contain
levels of radionuclides of regulatory significance in radiation protection terms. The
residues generated in mining and milling activities differ from those generated at, for
example, nuclear power plants or medical facilities. An important difference affecting
their management is the very large volumes of many of these residues. This has
important consequences to the possible siting and engineering options that are
available. In addition, radon and many of the very long half-lived radionuclides
presented in these residues implies that long term concerns should be fully addressed
in term of the protection of future generations against radiation risk.
1.3 For the purposes of the Standards, NORM is defined as: “Radioactive material
containing no significant amounts of radionuclides other than naturally occurring
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radionuclides” [1]. It includes material in the natural state as well as material in which
the activity concentrations of the naturally occurring radionuclides may have been
changed by man-made processes, including the residues from these processes.
Radioactive material is defined as “Material designated in national law or by a
regulatory body as being subject to regulatory control because of its radioactivity“.
All residues from the mining and processing of raw materials that are subject to
regulatory control in terms of the IAEA’s safety standards, including residues from
uranium and thorium mining and processing, fall within the definition of NORM and
are thus known as NORM residues. A NORM residue is defined as “Material that
remains from a process and comprises or is contaminated by naturally occurring
radioactive material (NORM)”. NORM waste is defined as “Naturally occurring
radioactive material (NORM) for which no further use is foreseen” [1]. A NORM
residue therefore may or may not be waste.
1.4 Various publications in the IAEA Safety Standards Series have some
relevance to NORM and NORM residues, covering issues such as the management of
wastes from uranium and thorium mining, clearance and exemption levels for
radionuclides of natural origin, and worker protection in mining and mineral
processing related industries [2-7][SF-1, GSR-Part1, SSR-5, RS-G-1.7, RS-G-1.6,
WS-G-2.3]. However, there has been relatively little guidance specifically on the
management of NORM residues (including NORM residues designated as waste)
arising from other industries such as titanium dioxide pigment industries, metal
smelting, phosphate fertilizer production, oil and gas, coal, mineral sand exploitation,
and water treatment. This Safety Guide is intended to fill that gap, by focusing on the
identification and implementation of appropriate measures for protection of members
of the public and the environment against radiological hazards associated with the
management of all types of NORM residue encountered across a range of industrial
operations.
1.5 Many Member States have established regulations and guidance for the
licensing and control of waste arising from existing operations for the processing of
uranium and thorium ores. Uranium and thorium containing ores, beneficiated
mineral, and associated mining waste such as overlying rock or sediment
(overburden) at closed mine sites, waste liquids and sludges, contaminated plant and
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equipment, tailings from the extraction of the uranium and thorium wastes at a closed
processing facility or legacy sites may also be considered to be NORM residues.
1.6 Many of the industries and processes whichthat generate NORM residues have
not traditionally been considered to have an association with radioactivity. Thus, the
introduction of radiation protection requirements, in compliance with the Standards,
can potentially cause considerable public concern, especially where industries have
been located in or near areas of high population. Equally, the introduction of such
requirements can have a significant impact on the industries themselves. This guide is
intended to assist such industries in assessing their radiation protection obligations;
and to assist regulatory authorities to determine the appropriate level of control to be
implemented.
1.7 NORM residues are often produced in very large volumes, although the
activity concentration of radionuclides is relatively low. However, there are some
residues where the volumes are smaller and where the levels of radioactivity are
relatively high. There is also the possibility that a NORM residue from one industry
may be regarded as a waste, whereas in another industry or another country, the same
material may be regarded as a raw material or a feedstock for further processing.
1.8 The radionuclides contained in NORM residues may not be the only potential
hazard to individuals and the environment. Other chemical constituents within the
material may be capable of causing harm. These include heavy metals, inorganic
elements (e.g. arsenic) and various organic compounds. The potential for such non-
radiological substances to cause detriment needs to be considered when planning the
management of NORM residues. Achieving a consistent regulatory approach to
protect against these different hazards is a challenge for national regulators. This
publication is focused on the management of the radiological hazards associated with
the waste. However,, there is a particular need for regulators to take account of the
non-radiological hazards that in some cases may represent the primary risk to people
and the environment..
1.9 This publication supersedes Management of Radioactive Waste from the
Mining and Milling of Ores, Safety Guide Series No. WS-G-1.2, issued in 2002 [8]. Formatted: Highlight
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OBJECTIVES
1.10 The objective of this safety guide is to provide recommendations and guidance
to regulatory bodies, operating organizations, technical support organizations, and
other interested parties on safe management of radioactive residues including those
designated as waste, arising from the mining, milling and processing of ores
(primarily uranium and thorium), and from other activities generating NORM
residues, in accordance with the relevant Safety Requirements for protection of
human health and the environment from exposure to ionizing radiation now and in the
future [GS-R-13], DS353,, WS-G-2.3[7]. The guidance will address new facilities;
however, this guide may also be relevant to the review and upgrading of existing
facilities where reasonably practicable. The guide is to address residues arising during
all phases of a facility lifetime. However, in accordance with national policies,
appropriate steps may be taken to review the safety of existing facilities (including
legacy sites) and, where reasonably practicable, to upgrade their safety in line with the
relevant recommendations set out in this Safety Guide.
SCOPE
1.11 The scope of this Safety Guide covers pre-operational, operational, closure
and post-closure activities at facilities that deal with NORM residues.
1.12 The Safety Guide will provide life cycle guidance on the site selection and
evaluation and design of NORM residue management facilities, and on their
construction, operation and closure, decommissioning and transfer to institutional
control, including organizational and regulatory requirements (GSR Part 1[3]). The
guide includes guidance on the development of a safety case and safety assessment
for facilities and activities involving NORM residues, as required by GSR Part 4[9],
[10].and GSR Part 5 [GSR Part 4; GSR Part 5].
1.13 This guide is intended to be applicable to the mining and milling of ores for
the extraction of uranium or thorium, to other industries including mining and
processing of other ores, the oil and gas industry, the phosphate industry, and other
activities resulting in the production of NORM residues. Regulatory bodies should
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determine the extent to which this guidance should be applied to particular industries
in accordance with a graded approach.
1.14 This guide applies to both small volume and bulk amount of residues, and not
discrete sources, such as radium sources for which management is covered in other
IAEA documents. In this Safety Guide, the term “bulk residues” generally refers to
large volume wastes of the sort typically generated by mining and mineral processing
activities and includes tailings, waste rock, mineralized waste rock and large volumes
of liquid wastes (process water, leaching fluids, seepage and run-off). It may also
include large volumes of downstream processing wastes (such as fly ash or bottom
ash from power generation).
1.15 This guide is also intended to cover management of contaminated plant and
equipment, as well as the radioactive residues generated by the decontamination
process.
1.16 This Safety Guide is principally directed towards the management of residues
generated by new facilities, and residues arising from the proposed decommissioning
and remediation activities associated with those facilities1. It may not be practical to
apply all of these recommendations to existing facilities and in such cases the
regulatory body should decide the extent to which these recommendations apply.
1.17 Radiological safety in the production and processing of U/Th ores is addressed
in other IAEA publications [6], [7]. The control of occupational and public exposures
and environmental impacts due to routine radioactive releases or transport of waste is
also discussed in other IAEA safety standards2 [11].
STRUCTURE
1.18 The administrative, legal and regulatory framework, and scope of regulatory
control needed for the safe management of NORM residues, is described in Section 2.
Protection of people and the environment for safety management of NORM residues
is described in Section 3. Strategies for managing residues are discussed in Section 4.
1 Note the distinction between usage of the terms “Closure” and “Decommissioning” in IAEA Glossary Ref[1].
2 Including DS353: in preparation.
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Safety considerations in long-term management of residues generated in all phases of
the lifetime of a management facility are discussed in Section 5. A process for
considering all the relevant issues associated with developing a NORM residue
management strategy and residue management facilities to ensure that human health
and the environment are afforded an acceptable level of protection (the ‘safety
assessment and safety case’) is discussed in Section 6. Guidance on the design and
implementation of a management system for residue management is provided in
Section 7. A monitoring and surveillance programme for residue management
facilities is discussed in Section 8. Financial assurance for the long-term safety of
residue management facilities is discussed in Section 9.
REFERENCES – Chapter 1.
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2. ADMINISTRATIVE, LEGAL AND REGULATORY FRAMEWORK
INTRODUCTION
2.1 This Section outlines the legal and regulatory framework, and scope of
regulatory control needed for the safe management of NORM residues. The key points
are as follows:
The general responsibilities of Member States, the Regulatory Body, and the
Operator are summarized,
The development of a national inventory of industries concerned with the
production and processing of NORM is proposed, including a national
inventory of active and legacy sites and wastes produced by these industries,
The application of the concepts of exclusion, exemption and clearance, and use
of a graded approach are described,
Residue management strategies are discussed with an emphasis placed on re-use
and recycling of NORM residues where safe and appropriate to do so.
NATIONAL POLICY AND STRATEGY
2.2 Member States planning to engage in activities that generate, utilize or, require
management or disposal of NORM residues, are required to develop:
An appropriate national legal and organizational framework within which
NORM residue management activities can be planned and carried out safely;
A national policy for managing NORM activities and NORM residues,
including any waste associated with such operations;
A strategy for implementing this policy, including the provision of necessary
resources [GSR-13].
2.3 The policy and strategy should reflect, and be consistent with, the principles for
radioactive waste management as set out in Ref GSR[3] -1 and in Sections 3–6 of this
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publication. It should address and encourage the recycling of NORM residues and
their reuse in other applications, where safe and appropriate to do so. Recycling and
reuse of NORM residues is discussed further in Section 4 as options for residue
management, and more information on the application of these options is given in
Annex 2.
2.4 Member States should consider the need for, and the extent of, public
involvement and consultation during the regulatory process. Increasing public
consultation is a feature of the authorization process in many Member States.
However, the responsibility for the regulatory decision remains with the regulatory
body. The decision making process should be transparent, independent and defensible,
such that if a decision is challenged the regulatory body can explain how it was
reached.
2.5 The development of a residues management strategy is usually a complex
process that has the aim of achieving a reasonable balance between two, often
conflicting, goals: maximization of risk reduction and minimization of financial
expenditure. The process is one of optimization of protection in which the available
alternatives for siting, design and construction, operation, management of residues,
and closure are evaluated and compared, with account taken of all associated benefits
and detriments and any constraints (such as an annual dose constraint) that are
required to be imposed. The characteristics of the alternatives (or options) that should
be considered include:
The radiological and non-radiological impacts on human health and the
environment during operation and in the future;
The requirements for monitoring, maintenance and control during operation and
after closure;
Any restrictions on the future use of property or water resources;
The financial costs of the various alternatives and the resources available for
implementing the alternatives;
The volumes of the various residues to be managed;
The socioeconomic impacts, including matters relating to public acceptance;
Good engineering practices.
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2.6 The steps taken towards deciding how to manage the residues arising from
NORM facilities should include:
Definition of the criteria for human health and environmental protection;
Characterization of the residues;
Identification and characterization of the site options;
Identification and characterization of the residues management options,
including engineering controls;
Identification and description of options for institutional control;
Identification and description of potential failures of institutional and
engineering controls;
Definition and characterization of the representative person of the population;
Estimation of the radiological and other consequences for each combination of
options being considered (the ‘safety analysis’), including scenarios of potential
exposure for each option;
Comparison of the estimated doses and risks with appropriate constraints;
Optimization of protection so as to arrive at the preferred management option.
2.7 The evaluation criteria and procedures used to select the preferred options and to
develop the residues management strategy that will achieve the optimal balance
among the above considerations should be clearly defined and presented to the
different interested parties in the project, including the public.
2.8 The design of NORM residue generating facilities will influence the
optimization of protection from exposure due to radioactive residue and should
therefore be considered with residue management in mind. The NORM generating
activities should be designed to reduce, as far as practicable, the amount of waste to be
managed. This can be accomplished through the choice of appropriate NORM
processes, and the recycle and reuse of equipment, materials and residues.
2.9 The closure of the residues management facilities should be considered in all
phases of the NORM operation, that is, during siting, design, construction and
operation. Planning for the management of NORM residues at closure should already
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be addressed in the siting and design phase, and not be delayed until the closure stage.
For example, taking measures at an early stage to reduce the migration of water-borne
and airborne contamination to the surrounding environment will facilitate
management of the closure phase.
2.10 The design, construction, operation and closure of facilities for the handling,
storage and disposal of residues from NORM operations should be in accordance with
the elements of a management system as outlined in Section 7. In particular, facilities
should be constructed, operated and closed only according to approved plans and
procedures.
2.11 Section 5 of this guide outlines the important characteristics and desirable
features of the options that should be considered in the siting and management of
residues from NORM activities, including considerations inin the siting, design,
construction, operation and closure of facilities, the release of materials and the factors
for institutional control.
RESPONSIBILITIES
2.12 According to the Safety Requirements, governments of Member States are
required to have an appropriate legal and governmental infrastructure for nuclear,
radiation, radioactive waste and transport safety (see para 2.1). The principal parties
responsible for facilities and activities (the operator), also have responsibility for
protection and safety [(GSR-311)]. Furthermore, responsibilities associated with
management of radioactive waste are laid out in Refs [4] &(SSR-5; GSR-5[10]). The
requirements and responsibilities with specific relevance to the management of
NORM residues are considered in this Section.
2.13 Processing of minerals and raw materials may result in radioactive
contamination of equipment and items such as pumps, separators, piping, tanks,
containers and filters. When Member States are developing a national policy and
strategy for NORM residues, they should ensure that the management of such
contaminated items (including decontamination, storage and disposal) is taken into
account.
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2.14 The responsibility for regulatory decision-making rests with the regulatory body.
However, the process of making decisions should be independent and transparent. The
process should also be defensible. The process should include adequate provision for
public consultation and to ensure that the views of all stakeholders have been taken
into account to the extent practicable.
2.15 A graded approach to regulation is one of the key principles embodied in the
Standards, and this is especially relevant in respect of activities involving NORM,
including the management of NORM residues, where exposures are generally
moderate, even in the event of accidents, and where occupational health and safety
(OHS) measures and environmental protection measures are already in place3 4
(Requirement 7 of Ref [GSR Part 3: Requirement [117]).
2.16 The detailed requirements for the responsibilities of each of the participants
involved in the management of NORM residues have been set out in Refs. [GS-R-13]
and [WS-R-311]. General requirements, relevant to the management of NORM
residues are described in Section 4. below.
MEMBER STATES
2.17 Member States are required to establish and maintain a regulatory body and
ensure that it is “effectively independent in its safety related decision making and that
it has functional separation from entities that have responsibilities or interest that
could unduly influence its decision making” [3[GSR-1; Requirement 4]. This
requirement applies equally to NORM industries, from which the regulatory body
should be independent. Also, the regulatory body “shall have sufficient authority and
sufficient staffing and shall have access to sufficient financial resources for the proper
discharge of its assigned responsibilities” [GSR-1; (Requirement 4 of Ref [3])]. In
some cases the potential radiological significance of NORM processing industries is
3 Such measures are applied to control other (non-radiological) hazards in the workplace, but may well provide
some protection against radiological hazards as well. The most common examples are measures to restrict airborne
dust in the workplace and measures to limit the pollution of water sources in the environment.
4 Such measures are applied to control other (non-radiological) hazards in the workplace, but may well
provide some protection against radiological hazards as well.. The most common examples are measures to
restrict airborne dust in the workplace and measures to limit the pollution of water sources in the
environment.
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only now being recognized, and it should also be recognized that a commensurate
increase in regulatory body resources may be required. However, it is also possible for
an existing regulatory body to simply incorporate management of radiological hazards
into its existing requirements.
2.18 Member States should determine which industries within their jurisdiction are
concerned with the production and processing of NORM. A national inventory of sites
and wastes produced by these industries should be compiled, as discussed in Section
4. Member States should also consider compiling a national inventory of legacy sites,
i.e. sites known to contain significant quantities of NORM residues from discontinued
and past practices. The combined (past and present) quantities of NORM residues
should then be used as a basis for determining what residues management facilities are
required.
2.19 Member States should make provisions for dealing with situations where an
operator is not able to meet their responsibilities. These include situations involving
operational facilities (e.g. where the operator becomes insolvent) and legacy situations
(i.e. where no legally responsible operator exists)) [WS-R-8; para 4.4]..
2.20 A system for archiving, retrieval and amendment of all important records
concerning the initial characterization of the area, the choice of options for
remediation and the implementation of remedial measures, including all restrictions
and the results of all monitoring and surveillance programprogrammes, shall be
established and maintained in all cases. Member States should ensure that the
appropriate arrangements are made for record keeping.
REGULATORY BODY
2.21 The regulatory body is responsible for authorization, regulatory review and
assessment, inspection and enforcement, and for establishing safety principles,
criteria, regulations and guides [GSR-510]. In establishing a regulatory system the
complete life cycle of each NORM processing industry should be considered, so that a
consistent regulatory approach to the production and management of residues is
achieved. Within such a regulatory system, it is quite possible that only a few facilities
or processes may require regulatory control.
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2.22 In establishing the safety principles, criteria, regulations and guides, the
regulatory body should address and encourage the recycling of NORM residues and
their use in other applications where safe and appropriate to do so. This may include
making provision for regulating the recycling of lightly contaminated materials (e.g.
steel) where it is safe and appropriate to do so.
2.23 The regulatory body is responsible for determining which facilities or processes
require regulatory controls. An example of the regulatory process for a new NORM
facility is provided in Fig. 1 (below), from which the regulatory process in individual
States may differ in detail. The regulatory body should ensure that all legal
requirements have been fulfilled by the operator. A graded approach should be
adopted to achieve the optimum level of radiation protection. This should include a
consideration of the benefits that can be achieved in practice, and the social and
economic factors involved. Small operations or local community services (e.g.
drinking water treatment plants) may be jeopardized economically by the need to
implement regulatory controls. In such cases a decision should be made on the most
appropriate manner in which to implement adequate controls to achieve a clear overall
benefit.
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Fig 1. {Inserted Fig 1 of WS-G-1.2 [Ref 9.] here, NOTE for the secretariat: to adapt
text in the figure and in the title (waste = residue; mining and milling = NORM
operations) and to include the possibilities of recycling and reuse in the pre-
operational and operational phase}
2.24 The regulatory body is responsible for verifying that the operator has met all the
obligations under the appropriate regulations. When a NORM processing facility has
been closed down, there needs to be assurance that the operator has met all the
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obligations under the appropriate regulations. The dismantling of NORM processing
plants can reveal NORM residues and contamination that were not apparent during the
operational phase. This possibility should be considered by the operator prior to the
plant being dismantled.
2.25 The regulatory body should ensure that it maintains the necessary technical
expertise to evaluate NORM processes and the ways in which NORM residues are
produced and might be used in other applications. In addition the regulatory body
should have a good understanding of the technical and financial circumstances of the
operator of each NORM residues facility, so as to ensure that the facility is operated
safely and that sufficient funding has been allocated to allow for response to any
accidents. This should extend to the knowledge that operators have available sufficient
financial and human resources and provision for interim storage for the NORM
residues, to enable not only the safe and efficient management of NORM residues, but
also a capability to manage final closure operations and remediation as required.
OPERATOR
2.26 Operators shall be responsible for the safety of radioactive waste management
facilities or activities [10]. The operator shall carry out safety assessments and shall
develop a safety case, and shall ensure that the necessary activities for siting, design,
construction, commissioning, operation, shutdown and closure are carried out in
compliance with legal and regulatory requirements. These responsibilities apply where
necessary also to facilities where NORM residues are managed. The safety of facilities
should incorporate consideration of the protection of humans (workers and public) and
the environment. Guidance on the safety case and safety assessment for predisposal
management and disposal of radioactive waste is discussed further in Section 6.
2.27 The operator of facilities for managing NORM residues is responsible for all
aspects of safety of the facility, including the protection of workers, the public and the
environment from any hazards associated with the residues, up to and including the
completion of closure of the facilities. The operator is also required to be responsible
for complying with all legal requirements. If, for any reason, the operator can no
longer assume this responsibility, it should be assumed by a governmental
organization.
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2.28 The operator of NORM facilities should develop technical and administrative
proposals, within the framework of a management system for all aspects of the
protection of human health and the environment, which should be adopted subject to
review and approval by the regulatory body.
2.29 The operator is required to be responsible for the identification of the technical
possibilities and methods to minimize the generation of NORM residues, by means of
appropriate design measures and procedures, including the recycling of NORM
residues and their use in other applications where safe and appropriate to do so
(Principle 7 of Ref [2][SF-1, Principle 7]).
SCOPE OF REGULATORY CONTROL
2.30 The selection of appropriate criteria for defining the scope of regulatory control
is an issue for all NORM activities. The number of facilities involved in the
processing of minerals and raw materials is very large, but relatively few of them
represent significant radiological hazards. Inappropriate selection of criteria could
result in many of such facilities having to be regulated without any net benefit. For
this reason, the concepts of exclusion, exemption and clearance are especially
important in defining the scope of regulatory control of natural sources [RS-G-1.75],
including the management of NORM residues.
2.31 Once the regulatory body has decided that a NORM activity falls within the
scope of regulatory control a graded approach of control should be applied, in
accordance with the [GSR GSR Part 3 (Interim)]. 11]. The graded approach of control
shall be commensurate with the characteristics of the NORM activity and with the
magnitude and likelihood of the exposures.
Exclusion
2.32 It is usually unnecessary5 to apply regulatory controls to NORM activities,
including the management of NORM residues, where the activity concentration of
5 Materials with activity concentrations below the values in Table 1 should generally be
considered as being of no regulatory concern. However, as mentioned in paragraph 5.1 of
Ref. [5], there are some situations for which some type of regulatory control may still be
appropriate, for example the use of building materials containing certain NORM residues.
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radionuclides does not exceed the values in Table 1. (below) [5], [13]. These values,
based on the concept of exclusion (non-amenability to control), should be used to
define the scope of regulation. They are valid for the natural decay chains in secular
equilibrium, i.e. 238
U, 235
U and 232
Th with the value given being applied to the parent
of the decay chain. The values can also be used individually for each decay product in
the chains or the head of subsets of the chains, such as 226
Ra.
2.33 A specific use of the exclusion principle applies to the transport of NORM. The
Regulations for transporting radioactive materials are laid down in Ref [12]TS-R-1.
Table 1. Values of activity concentration for radionuclides of natural origin
Radionuclide Activity concentration (Bq/g)
40K 10
All other radionuclides of natural origin 1
Exemption
2.34 According to GRS Part 3, tThe general criteria for exemption [11] are that:
Radiation risks arising from the practice or a source within a practice are
sufficiently low as not to warrant regulatory control, with no appreciable
likelihood of situations that could lead to a failure to meet the general criterion
for exemption; or
Regulatory control of the practice or the source would yield no net benefit, in
that no reasonable control measures would achieve a worthwhile return in terms
of reduction of individual doses or of health risks.
2.35 Processing of raw materials with radioactive concentrations in excess of the
values in Table 21 may need to be considered by the regulatory body, but should not
automatically lead to regulatory control. The regulatory body may decide that the
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optimum protection option is not to apply regulatory requirements [RS-G-1.7, (Para
5.12 of Ref [5])].
2.36 The Basic Safety Standards [11] use the concept of exemption only within the
context of practices. Exemption determines a priori which practices, sources and
radioactive materials may be freed from the requirements for practices, and hence
regulatory control, based on certain criteria. Exemption should be granted if the
regulatory body is satisfied that the practices or sources meet the exemption criteria
specified by the regulatory body.
2.37 The likely doses from work with NORM at different activity concentrations
have been estimated [RS-G-1.5]&; RS-G-1.7[6], and may serve as the basis for
material-specific exemption levels. It should normally be unnecessary to apply
regulatory controls to work activities involving exposure to NORM if the effective
dose6 received by a worker or member of the public does not exceed about 1 mSv in a
year.
2.38 The doses arising to members of the public who live near NORM residue
management facilities with radionuclide specific activity concentrations of the natural
uranium (238
U-238) and natural thorium (232
Th-232) decay series of 1Bq/g or less, are
considered unlikely to exceed about 1 mSv in a year “excluding the contribution from
the emanation of radon” [RS-G-1.75].
Clearance
2.39 The general criteria for clearance [GSR Part 3 (Interim11)] are that:
Radiation risks arising from the cleared material are sufficiently low as not to
warrant regulatory control, with no appreciable likelihood of occurrence for
scenarios that could lead to a failure to meet the general criterion for clearance;
or
6 Excluding the contribution from radon, which is dealt with separately in the Standards.
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Continued regulatory control of the material would yield no net benefit, in that
no reasonable control measures would achieve a worthwhile return in terms of
reduction of individual doses or of health risks.
2.40 Clearance is intended to establish which sources under regulatory control can be
removed from this control. It is based on clearance levels, defined as 'values
established by the regulatory body and expressed in terms of activity concentrations...
at or below which sources of radiation may be released from regulatory control' [11].
2.41 In terms of the processing of NORM and the management of NORM residues,
the concepts of exclusion, exemption and clearance are often closely linked, or even
overlap, depending on the material involved. As such, it may be appropriate to
establish a single set of levels both for exemption and clearance, using the same basis
as that applied to exclusion of exposures from NORM. Below this level no further
regulatory consideration need be given to the material and it should be disposed of as
normal7 (non-radioactive) waste.
2.42 Clearance of NORM residues containing activity concentrations above 1 Bq/g
may still be appropriate, in certain situations, providing the regulatory body is satisfied
that future exposures from such materials will be insufficient to require the
reinstatement of controls.
2.43 For radionuclides of natural origin in residues that might be recycled into
construction materials8 or the disposal of which is liable to cause the contamination of
drinking water supplies, the activity concentration in the residues does not exceed
specific values derived so as to meet a dose criterion of the order of 1 mSv in a year,
commensurate with typical doses due to natural background levels of radiation.
2.44 Clearance may be granted by the regulatory body for specific situations, on the
basis of the criteria specified by the regulatory body, with account taken of the
physical or chemical form of the radioactive material, and its use or the means of its
7 Disposal of such materials may still be subject to control due to it having other hazardous properties.
8 Regulatory control of construction materials is addressed in Section 5 of Ref [11] as an existing exposure
situation.
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disposal9. Such clearance levels may be specified in terms of activity concentration
per unit mass or per unit surface area.
After closure
2.45 The regulatory body is responsible for the regulation of all phases of
decommissioningclosure, from initial planning to termination of the practice or final
release of the facility from regulatory control. The responsibilities of the regulatory
body include establishing safety and environmental criteria for the
decommissioningclosure of facilities, including criteria for clearance of material
during decommissioningclosure and conditions on the end state of
decommissioningclosure and on the removal of controls.
GRADED APPROACH FOR IMPOSING CONTROL
2.46 It is important that a graded approach for imposing regulatory control is applied,
bearing in mind existing occupational health, safety and environmental control
measures, and only applying additional controls where these are necessary to reach an
optimum level of radiation protection. Due account should be taken of social and
economic factors when determining what is the optimum level of protection.
Notification
2.47 A NORM residue may be identified by the operator or the regulator. If the
NORM residue cannot be exempted, the second step in the graded approach to control
of the source has to be applied. In that case, the operator is required to formally submit
a notification to the regulatory body.
2.48 Notification alone could be sufficient where exposures are unlikely to exceed a
small fraction, specified by the regulatory body, of the relevant limits. In practical
terms, this is similar to exemption, but with the important difference that the
regulatory body is kept informed of all such operations or processes. The existence of
more general occupational health and safety measures would be an important factor in
deciding whether notification alone was the optimum regulatory option.
9 For example, specific clearance levels may be developed for metals, rubble from buildings and waste for
disposal in landfill sites.
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2.49 When the activity concentration exceeds 1 Bq/g for the U and Th-series
radionuclides or exceeds 10 Bq/g for K-40, the residue should be analyzed to identify
potential risk. First, a screening assessment should be conducted. This assessment
should be subjected to careful review.
SCREENING ASSESSMENTS
2.492.50 Upon receiving a notification, the regulator may require an initial
screening risk assessment to be made to estimate:
The magnitude of worker and member of public doses arising from the
operation;
The level of optimisation of radiation protection;
The long term impact of any residues on the environment in the case of
disposal;
The impact of residues containing NORM or contaminated materials that may
be recycled;
2.502.51 The screening assessment should be specific to the particular operation
and should be negotiated between the operator and regulator. The assessment may be
based on existing information relating to the operation, its processes and waste/residue
management methods, or be based on an agreed monitoring programme to provide
more data. Procedures for carrying out data collection are described in Annex 3.
2.512.52 Possible outcomes of the screening assessment include unconditional
exemption, conditional exemption (including periodic review), and authorisation
possibly including registration or licensing. This process is shown schematically in
Figure 2.
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Figure 2: The basic process for management of NORM
2.53 If the screening assessment indicates that the exposure of workers and the public
to the natural radionuclides in the NORM residue gives rise to doses less than 1 mSv/y
and is likely to remain so throughout the lifetime of the residue, the residue may be
granted exemption from regulatory control, which is the first step in the graded
approach.
2.522.54 If the screening assessment indicates that the dose may exceed 1
mSv/y, a more detailed assessment may need to be conducted and may include:
more realistic assumptions and exposure scenarios;
the collection of more site data to improve the estimation of the source term and
transfer parameters;
more complex models if considered appropriate.
Identification by
regulator
Notification
by operator
Screening assessment
Unconditional
exemption
Authorization
(registration/
license)
Conditional
exemption
More detailed assessment
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2.532.55 In some cases the detailed assessment may indicate that exemption is
still appropriate, because the application of control measures will not improve the
level of radiation protection.
2.542.56 In the event of significant process change, or where external events
have impacted on the operation (flooding, fire, land slippage, subsidence) a new
assessment may be required. The operator and regulator should review the situation
after a mutually agreed period to check whether exemption is still appropriate.
Authorization
2.552.57 Where the nature of the hazard is such that further obligations beyond
notification need to be placed on the operator, the Standards require that application is
made to the regulatory body for an authorization. In accordance with the graded
approach to regulation, the authorization may take the form of either a registration or a
licence, the difference being essentially in the level of stringency of regulation.
Registration, which typically places only limited obligations on the legal person, may
provide a sufficient level of control in many operations involving significant, but
nevertheless moderate, exposures to NORM and/or radon.
2.562.58 In situations where optimized protection can only be achieved through
the enforcement of specific exposure control measures, licensing may be the more
appropriate form of authorization. Licensing represents the highest level in the graded
approach to regulation, and the need for licensing of operations giving rise to exposure
to NORM will probably be largely limited to operations involving significant
quantities of material with very high radionuclide activity concentrations.
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3. PROTECTION OF PEOPLE AND THE ENVIRONMENT
INTRODUCTION
3.1 This Section outlines the basic requirements for the radiological protection of
workers, the public, and the environment in relation to the management of NORM
residues. The key points are:
Referencing of primary guidance on radiation protection plans and the setting of
dose limits, dose constraints, and releases of NORM residues to the
environment.
Insuring the protection measures adopted should be commensurate with the
magnitude and likelihood of exposures from the particular NORM residues
present
GENERAL PRINCIPLES
3.2 National requirements for radiation protection are required to be established,
keeping in view the fundamental safety objective and fundamental safety principles
set out in Ref. [2] and in compliance with the International Basic Safety Standards
Interim [11]. In particular, doses to persons as a consequence of the storage or
disposal of NORM residues are required to be kept within specified dose limits and
radiation protection is required to be optimized within dose constraints.
3.3 The management of NORM residues is part of the management of a facility
and activity as defined in Ref [11] and radiation protection considerations are
therefore governed by the principles of justification, optimization and dose limitation.
The generation and management of NORM residues do not need to be justified since
this will have been taken into account in the justification of the entire practice.
3.4 If several radiation facilities and activities are located at the same site, the
dose constraints for public exposure should take into account all sources of exposure
that could be associated with activities at the site, leaving an appropriate margin for
foreseeable future activities at the site that may also give rise to exposure. Particularly
in such cases, the regulatory body should require the operating organization(s) of the
facility and activity on the site to develop constraints, subject to regulatory approval.
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Alternatively, the regulatory body may establish the dose constraint(s). Requirements
on dose constraints are established in Ref. [11] and recommendations are provided in
Ref. [6].
3.5 Discharges to the environment from NORM facilities and activities should be
controlled in accordance with the conditions imposed by the national regulatory body
and should be included when estimating doses to workers and to the public.
3.6 The adequacy of control measures taken to limit the radiation exposure of
workers and the public should be verified by monitoring and surveillance, both inside
and outside the facility.
3.7 In the generation of NORM residues, as well as in subsequent management
steps, a safety culture that encourages a questioning and learning attitude to protection
and safety and that discourages complacency, should be fostered and maintained [11].
RADIATION PROTECTION
3.8 The fundamental safety objective of managing NORM residues is to protect
people and the environment from harmful effects of ionizing radiation (SF-1 Section
2). To achieve this objective, radiological protection of workers, members of the
public and of the environment needs to be considered at all stages of management of
NORM residues. These stages include planning and designing of the processes and
equipment, operation, and the closure of the operation and rehabilitation of the site.
3.9 There are three types of radiation exposure situation that need to be
considered: planned exposure, emergency exposure, and existing exposure [11].
3.10 Planned exposure arises from a planned operation, and the planning will
include consideration of how exposures and their likelihood of occurrence can be
restricted. Exposure can be controlled by good design of facilities and operating
procedures, and by training.
3.11 Emergency exposure arises as the result of an accident or unexpected event
and requires prompt action to avoid or reduce the consequences. In general the
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concentration of radionuclides in NORM residues is not high enough to result in
doses that would produce radiological emergencies. Nevertheless emergency
situations can arise and prompt action may be necessary, for example in order to
safeguard the integrity of storage or disposal facilities. Appropriate contingency
plans must be developed prior to the operation of any facilities that manage or
produce NORM residues.
3.12 An existing exposure situation is one where the source of exposure and an
exposure pathway already exists. In the case of NORM residues this type of exposure
may arise from situations where NORM residues from past practices have been
abandoned or are otherwise not under regulatory control. However, where a decision
is made to remediate such residues, this will be a planned operation and exposures
arising from such remediation will be planned exposures.
3.13 In all cases it is important that a graded approach to radiation protection
should be adopted. That is, the protection measures adopted should be commensurate
with the magnitude and likelihood of exposures from the particular NORM residues
present.
Radiological Protection of Workers
3.14 Workers may be exposed during the generation of the NORM residues, during
operations to process, re-use or recycle the residues, or during the disposal of NORM
wastes. In all cases where the NORM residues are subject to regulatory control a
radiation protection plan (RPP) that complies with the relevant standards [11] must be
prepared and implemented.
3.15 Radiation protection in the generation of NORM residues is usually dealt with
as part of the radiation protection programprogramme for the overall process that is
producing the residues. For example radiation protection in the generation and
handling of uranium mill tailings will be a part of the overall radiation protection
program for the mill.
3.16 In other cases the NORM residue may be the only material in the whole
process where the concentration of radionuclides is sufficient to generate doses
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requiring management, in which case the radiation protection programme will be
specific to the NORM residue. This will also be the case where the NORM residues
are pre-existing.
3.17 In general, occupational radiation protection in the management of NORM
residues involves consideration of three main exposure pathways:
External exposure to radiation (primarily gamma radiation) emitted by the
material
Intakes of material (primarily through dust inhalation);
Inhalation of radon (and sometimes thoron) released from material into the air10
.
3.18 Other exposure pathways, such as ingestion from hand to mouth transfer, may
need consideration but the doses that may arise are usually much less than for the
other pathways.
3.19 In developing the RPP for management of NORM residues, the requirements
of [11] must be implemented, particularly the requirements for Planned Exposure
Situations. Dose limits for workers in planned exposure situations are detailed in
Schedule III of Ref [11]. In particular the occupational exposure of workers at
NORM processing facilities (including those who work with NORM residues,
whether on operational or legacy sites) from all sources should not exceed: an
effective dose of 20 mSv per year averaged over five consecutive years; an effective
dose of 50 mSv in any one year; an equivalent dose to the lens of the eye of 20 mSv
in a year, and an equivalent dose to the extremities (hands and feet) or skin of 500
mSv in one year [11].
3.20 It is also required that radiological protection be optimized so that doses to the
workforce are as low as reasonably achievable, social and economic factors being
taken into account11
[11].
10 The terms “radon” and “thoron” include not only the parent radionuclides, 222Rn and220Rn respectively, but
also their short-lived progeny.
11 More detailed guidance on preparation and implementation of a RPP is included in DS 453 Occupational
Radiation Protection in preparation.
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Radiological Protection of the Public
3.21 Radiation exposures to members of the public from NORM residues may
occur as existing exposures or as planned exposures. Existing Exposure Situations
involve those situations where pre-existing NORM residues are giving rise to
exposure of members of the public. Where members of the public have access to the
site on which NORM residues are disposed exposure can arise directly from those
residues, but exposure more commonly arises in the area surrounding the NORM
residues where radionuclides have been dispersed by airborne or waterborne
pathways.
3.22 The main pathways for exposure of members of the public in existing
exposure situations are:
External exposure to gamma radiation emitted by the material;
Intakes of material due to dust inhalation, either directly or via re-suspension;
Intakes of material by ingestion, either directly (e.g. inadvertent ingestion of
contaminated soil) or from ingestion of food or water;
Inhalation of radon (and, very rarely, thoron) released from material into the air.
3.23 As most if not all NORM radionuclides are normally present in the
environment, and contribute to natural background radiation, it is important that care
be taken to distinguish between exposures arising as a result of the presence of
NORM residues, and those arising from natural background.
3.24 The dose limits applicable to planned exposure situations do not apply to
existing exposure situations. Instead such exposures should be investigated to
determine if remedial actions or protective actions are justified, and that the extent of
such actions is optimized [11].
3.25 Planned exposure situations are those where members of the public are
exposed as a result of situations that are planned. These situations will include those
where exposure results from the generation of NORM residues, as the result of
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treatment of residues for re-use or recycling, or from remediation of existing NORM
storage or disposal sites.
3.26 The pathways for exposure of members of the public in planned exposures
situations are similar to those outlined for existing exposure, although it is possible
that re-use or recycling of NORM residues may introduce new pathways.
3.27 Dose limits to members of the public in planned exposure situations are
detailed in Schedule III of Ref [11]. The main limit applicable in the case of exposure
from NORM residues is an effective dose of 1 mSv in a year, with a provision that in
special circumstances a higher value of effective dose could apply in a single year
could apply, providing that the average effective dose over five consecutive years
does not exceed 1 mSv per year. An example of a case where such special
circumstances might be considered to apply is a transitory increase in exposure during
planned remediation measures, when those measures will lead to a subsequent
reduction in doses over the long term.
3.28 The dose limits should apply both during operations involving NORM
residues, such as generation, re-use or recycling, or storage or disposal, and to
exposures occurring after the cessation of such operations. During operations, doses
can be assessed through monitoring: either direct monitoring of radionuclides in for
example ambient air or foodstuffs, or indirectly by monitoring discharges and
modeling the subsequent intakes and doses to members of the public.
3.29 There should be reasonable assurance that these controls will remain effective
for a specified period, and that during this period the dose constraint determined by
the regulatory body will continue to be met.
3.30 Engineering controls may fail because of natural processes (such as erosion)
or events that result in the release of increased amounts of radionuclides to the
environment. Due consideration should be given to the probability of failure of such
controls and to the likely impact in terms of the overall integrity of the facility and
any public exposure or environmental consequences.
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3.31 The potential for public exposures in excess of the dose constraint arising
from possible future re-development of, or unplanned intrusion into, closed NORM
waste disposal facilities, should always be considered, and appropriate institutional
controls prepared.
3.32 RADIOLOGICAL PROTECTION OF THE ENVIRONMENT
3.333.32 Release of NORM contaminants into the environment has the potential
to irradiate non-human biota. Such exposure is most likely to occur as a result of
airborne or waterborne transport of radionuclides from a facility into the environment,
although it may also arise where plants or animals live on or in un-remediated NORM
residues.
3.343.33 The standard of radiation protection required to protect people from
harmful effects is generally considered to also provide appropriate protection of the
environment. Nevertheless there is a need to be able to demonstrate that the
environment is protected from the harmful effects of radiation exposure in any
situation in which NORM residues may be released into the environment [11].
3.353.34 Such a demonstration would usually be by means of an environmental
assessment that identifies any target organisms in the relevant environment, estimates
the doses that may arise from transport of NORM residues into that environment, and
the likelihood of such doses resulting in harmful effects. Methods for these
assessments have been developed12
[13]. Generally an assessment of potential
radiological effects on the environment would be part of a more general assessment of
the impacts of the operations being considered.
12 Including DS427: in preparation
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4. GENERAL ASPECTS OF RESIDUE MANAGEMENT
INTRODUCTION
4.1 This Section deals with the general aspects of the management of NORM residues.
More specifically, it covers:
The establishment of an inventory of processes that lead to the generation and
handling of NORM residues;
The characterization of the residues in order to understand their physical,
chemical and radiological properties;
The segregation of the residues, in order to decide if the material can be
cleared, reused or recycled;
A description of the principles and approaches that can be applied to the
management of residues and waste;
A description of options to minimize waste production and to treat and
condition the residues, either for reuse, recycling or disposal as waste;
A description of the main types of NORM residues and waste.
INVENTORY OF PROCESSES GENERATING NORM RESIDUES
4.1 This Section deals with the general aspects of the management of NORM
residues. More specifically this Section covers:
The establishment of an inventory of processes that lead to the generation and
handling of NORM residues;
The characterization of the residues in order to understand their physical,
chemical and radiological properties;
The segregation of the residues, in order to decide if the material can be cleared,
reused or recycled;
A description of the principles and approaches that can be applied to the
management of residues and waste;
A description of options to minimize waste production and to treat and
condition the residues, either for reuse, recycling or disposal as waste;
A description of the main types of NORM residues and waste.
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INVENTORY OF PROCESSES GENERATING NORM RESIDUES
4.2 4.2 The Safety Requirements [10] state, “to ensure effective and efficient
management and control of radioactive waste, the government shall establish a
national policy and strategy on radioactive waste management…appropriate for the
nature and amount of radioactive waste in the country”. NORM residues may or may
not be waste, but in order to develop a comprehensive national policy and strategy on
the management of NORM residues, the nature and amounts of NORM residues need
to be investigated and quantified, regardless if any future use of the residues is
foreseen.
4.3 4.3 An important first step in the development of regulatory systems and
management practices for NORM residues is to understand how, when and where
elevated concentrations of naturally occurring radionuclides could occur. Mining and
milling of uranium ores has always been considered as part of the nuclear fuel cycle,
and therefore it has been regulated under this regime. Other industrial sectors,
materials and processes involving NORM may also require some form of regulatory
consideration. A list of industry sectors is:
Mining and milling of uranium ores;
Extraction of rare earth elements;
Production and use of thorium and its compounds;
Production of niobium and ferro-niobium;
Mining of ores other than uranium ore;
Production of oil and gas;
Manufacture of titanium dioxide pigments;
The phosphate industry;
The zircon and zirconia industry;
Production of tin, copper, aluminium, iron and steel, zinc, and lead;
Combustion of coal;
Water treatment.
4.14.4 Operation of these industries can result in a need for developing a national
inventory of NORM residues. An overview of the major industrial processes which
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generate NORM residues, their occurrence, and the types of products, wastes and
residues generated is given in Table 2.
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Table 2 Major industrial activities that generate NORM residues
Industry Products NORM residues
Mining and milling Mineral Tailings, waste rock,
process water
Mineral processing Metal Tailings, slag
Phosphate industry Fertiliser, phosphoric acid Phosphogypsum, scales
Power generation
(fossil fuels)
Electricity Ash, scales
Oil & gas production Oil, gas Scales, sludges, process
water
Water treatment Potable water Sludges, bio-solids, scales
CHARACTERIZATION AND SEGREGATION
4.5 4.5 Due to the diversity of NORM residues, in terms of activity
concentration, volume, physical and chemical state, identification based on certain
criteria and procedures is the first step to impose control of NORM residues. Proper
characterization and segregation of residues are very important factors in residue
management. Characterization helps in developing a complete understanding of the
physical, chemical and radiological characteristics of residue for sorting and shipping,
either for selected processing, reuse and recycle, or for storage and disposal.
Segregation favors the maximization of clearance, reuse or recycling of residues and
can reduce the volume of waste that requires final disposal. Proper sorting requires
staff training and additional space and containers in the residue collection and storage
areas.
OPTIONS FOR RESIDUE MANAGEMENT
Principles, approaches and options
4.6 4.6 Radioactive residues management comprises managerial,
administrative and technical steps associated with the safe handling and management
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of residues, from generation to release from further regulatory control or to its
acceptance at a storage or disposal facility. It is important that the NORM residues
management strategy forms an integral part of the overall waste management strategy
for the operation. Non-radiological aspects such as chemical toxicity also need to be
considered, since these will influence the selection of the optimal residues
management options. For sludges in particular, the constraints on waste disposal or
processing options imposed by non-radioactive contaminants will in many cases be
greater than those imposed by radioactive components.
4.24.7 4.7In view of the range of NORM residue types that can be generated in
industries at different times and the possibility of changes occurring in the ways in
which they are generated and managed, particular attention needs to be given to the
radiation protection issues which may arise in their management and regulatory
control. Because of the nature of the industry, and the fact that the activity
concentrations are often relatively low, there is often limited knowledge among the
staff about the radiation protection aspects of residues management. While the safety
principles are the same for managing any amount of radioactive residues regardless of
its origin, there may be significant differences in the practical focus of residues
management programmes.
4.8 4.8 The development of a waste management strategy is usually a complex
process that has the aim of achieving a reasonable balance between two, often
conflicting, goals: maximization of risk reduction and minimization of financial
expenditure. The process is one of optimization of protection in which the available
alternatives for siting, design and construction, operation, management of waste
streams, and closure are evaluated and compared, with account taken of all associated
benefits and detriments and any constraints (such as an annual dose constraint) that are
required to be imposed. The characteristics of the alternatives (or options) that should
be considered include:
The radiological and non-radiological impacts on human health and the
environment during operation and in the future
The requirements for monitoring, maintenance and control during operation and
after closure;
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Any restrictions on the future use of property or water resources;
o The financial costs of the various alternatives and the resources available for
implementing the alternatives;
The volumes of the various residues to be managed;
The socioeconomic impacts, including matters relating to public acceptance;
Good engineering practices.
o4.9 Table 2 shows a variety of residues generated by NORM industries, each of
them with specific characteristics. A major distinction in the management options for
residues relates to the volume of material under consideration. For the management of
large volumes of residues, such as those from uranium mining and milling and from
processing of ores, the options are different from comparatively small volumes of
residues such as sludge and scales.
4.34.10 A key element of the Safety Requirements [10] is that “Radioactive
waste arising shall be kept to the minimum practicable”. This is especially the case
with many NORM residues, where options for further safe use should always be
explored first. This includes re-use or recycling within the process itself or use as an
input material to a different process or product. NORM residues should only be
designated as NORM waste where no further viable, safe use for the material can be
identified. Further details on re-use and recycling of NORM residues is given in
Annex 2.
o4.11 The three principle approaches to the management of radioactive waste are:
Delay and decay;
Concentrate and contain;
Dilute and disperse.
o4.12 The first principle, delay and decay, involves holding the waste in storage until
the desired reduction in activity has occurred through radioactive decay. Many NORM
residues contain radionuclides with long half-lives (e.g. 238
U, 232
Th, 226
Ra) and this is
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not a realistic management option for such wastes. It is, however, a realistic option for
residues containing only shorter-lived radionuclides, most commonly 210
Pb and/or
210Po.
4.44.13 The second principle, concentrate and contain, is widely used in the
management of wastes. The principle of concentrate and contain is predominantly
applied in the mineral processing industry. Though the containment of NORM
residues may be the best disposal option, this preference should not automatically be
assumed.
4.54.14 In all cases, the three principles for radioactive waste management are
not contradictive. Instead, they are complementary. An activity that generates
radioactive waste may use the first principle to allow for decay of short-lived
radionuclides and use the second principle for waste containing long-lived
radionuclides. For activities with artificial radionuclides this is the normal practice.
For many NORM residues, the third principle may be applied as being the
management principle of choice. In any case, every activity involving radioactive
waste needs to allow for the release of radionuclides by discharges, which might be
regulated by a license. The discharge is in fact the application of the third principle of
radioactive waste management.
4.64.15 When considering disposal options and any associated mitigating
options to reduce the impact on the public, account must always be taken of both the
radiological and other (non-radiological) hazards associated with NORM waste. In
many cases non-radiological hazards may well be the dominant factor to consider in
the selection of a disposal method. The selected disposal method should maximize the
protection of the public from all the hazards arising from the waste.
4.74.16 NORM residue management options include use as a raw material in
another process, re-use and recycling, and disposal. The selection of the most
appropriate management option depends on the regulatory requirements, type of
waste, form of the waste (e.g. particle size, liquid versus solid, etc.), quantities and
hazards associated with that particular waste, geographic location and geological
Pag e o f 1 25 41
conditions. The selection of management options for different categories of NORM
residues is discussed in the following sections.
Waste minimization
o4.17 Principle 7 of the Safety Fundamentals [2], states that radioactive waste must
be managed in such a way as to avoid imposing an undue burden on future
generations. This implies that the generations that produce the waste must seek and
apply safe, practicable and environmentally acceptable solutions for its long-term
management.
o4.18 Measures to control the generation of NORM residues, in terms of both
volume and radioactivity content, have to be considered before the construction of a
facility, beginning with the design phase, and throughout the lifetime of the facility.
These measures include the selection of the materials used for its construction, the
control of the materials and the selection of the processes, equipment and procedures
used throughout its operation and decommissioningclosure. Provided that protection
objectives are met, the control measures are generally applied in the following order:
reduce NORM residues generation, reuse items as originally intended, recycle
materials and, finally, consider disposal as waste.
o4.19 Authorized discharge of effluent and clearance of materials from regulatory
control, after some appropriate processing and/or a sufficiently long period of storage,
together with reuse and recycling of material, can be effective in reducing the amount
of residues that needs further processing or storage. The operator has to ensure that
these management options, if implemented, are in compliance with the conditions and
criteria established in regulations or by the regulatory body. The regulatory body also
has to ensure that the operator gives due consideration to non-radiological hazards in
applying such options.
o4.20 The general scheme for minimizing the volume of waste is presented in Fig. 3.
Pretreatment of waste is the initial step in waste management that occurs after waste
generation. It consists of, for example, collection, segregation, chemical adjustment
and decontamination and may include a period of interim storage. This initial step is
extremely important because it provides in many cases the best opportunity to
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segregate waste streams, for example, for recycling within the process or for disposal
as ordinary non-radioactive waste when the quantities of radioactive materials they
contain are exempt from regulatory controls. It also provides the opportunity to
segregate radioactive waste, for example, for near surface or geological disposal.
Figure 3 Basic steps in residues and waste management
Pre-treatment
o4.21 The processing of NORM residues will include pre-treatment operations such
as residues collection, segregation, chemical adjustment and decontamination. Pre-
treatment may result in a reduction in the amount of residues needing further
processing and disposal. Actions can be performed to adjust the characteristics of the
residues, to make it more amenable to further processing, and to reduce or eliminate
certain hazards posed by the waste owing to its radiological, physical and chemical
properties. In mining and mineral processing, segregation of benign waste rock from
mineralized waste rock, which requires special handling, is a pretreatment activity.
Treatment
o4.22 Treatment of radioactive waste includes those operations intended to improve
safety or economy by changing the characteristics of the radioactive waste. The basic
treatment concepts are volume reduction, radionuclide removal and change of
composition. Examples of such operations are: incineration of combustible waste or
compaction of dry solid waste (volume reduction); evaporation, filtration or ion
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exchange of liquid waste streams (radionuclide removal); and precipitation or
flocculation of chemical species (change of composition). Often several of these
processes are used in combination to provide effective decontamination of a liquid
waste stream. This may lead to several types of secondary radioactive waste to be
managed (contaminated filters, spent resins, sludges).
Conditioning
o4.23 Conditioning of radioactive waste involves those operations that transform
radioactive waste into a form suitable for handling, transportation, storage and
disposal. The operations may include immobilization of radioactive waste, placing the
waste into containers and providing additional packaging. Common immobilization
methods include solidification of liquid radioactive waste, for example in cement or
bitumen. Immobilized waste, in turn, may be packaged in containers ranging from
common 200 litre steel drums to highly engineered thick-walled containers, depending
on the nature of the radionuclides and their concentrations. In many instances,
treatment and conditioning take place in close conjunction with one another13
.
Immobilization of radionuclides in tailings
o4.24 Waste containing hazardous constituents that are mobile in the environment, or
constituents that enhance the mobility of radionuclides, should be immobilized or
stabilized. This is particularly important for the large volumes of mining and milling
tailings and stockpiles of NORM residues from processed raw materials, such as
phosphogypsum and red mud. Depending on the chemical composition of the natural
radionuclides and the physical matrix in which they are contained, the radionuclides
may be mobilized and contaminate the environment, i.e. the groundwater. Therefore,
measures to immobilize the radionuclides in the tailings and stockpiles should be
taken to assure the safety of the public in the surrounding environment. If hazardous
constituents are not immobilized or stabilized, it should be demonstrated for a facility
storing the waste that the constituents cannot migrate in a hazardous form or
concentration to the accessible environment.
Reuse and recycling
13 Further details on pretreatment, treatment, and conditioning can be found in DS 447.
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4.84.25 The introduction of improved process technologies and waste
minimization techniques such as reuse, recycling and use of NORM residues for new
purposes should be pursued provided that such activities are in accordance with the
Safety Fundamentals. The policy and strategy of NORM residues management should
address and encourage the recycling of NORM residues and their use in other
applications.
o4.26 Reuse can be defined as the reutilization of materials for the original purpose
in their original form or in a recovered state. Recycling is the utilization of valuable
materials, tools and equipment for other than the original purposes, with or without
treatment. The reuse and recycle options are attractive because there is strong
economic incentive to use the large volume of residues, to avoid the costs associated
with long term storage or disposal. The decision of whether or not to reuse and recycle
residues depends on many factors that are specific to a given stream of residue or
industry or country. Implementation of reuse and recycling options requires the
availability of suitable criteria, such as conditional and unconditional clearance levels,
a suitable measurement methodology and suitable instrumentation. More information
on reuse and recycling of NORM residues is given in Annex 2.
Storage and retrieval of residues
o4.27 Storage refers to the placement of the NORM residues in a facility where
appropriate isolation and monitoring are provided, with the intent of retrieval. Storage
may take place between and within the basic radioactive waste management steps.
Storage may be used to facilitate the next step in radioactive waste management, to act
as a buffer within and between radioactive waste management steps, or in awaiting the
decay of radionuclides until authorized discharge, authorized use or clearance can be
allowed. The same accounts for the storage of NORM residues.
o4.28 NORM residues will in general be stored in solid form as raw, pretreated,
treated or conditioned material. The intention of storage is that the material will be
retrieved for authorized discharge, authorized use or clearance or for processing and/or
disposal at a later time. The criteria for acceptance of the material in a storage facility
shall therefore take account of the known or likely requirements for subsequent
radioactive waste disposal. Safety requirements for the protection of human health and
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the environment shall be met by appropriate design, construction, operation and
maintenance of the respective facilities, including provision for the eventual retrieval
of the waste.
Disposal of NORM waste
o4.29 When no future reuse or recycling of the NORM residues is foreseen, the
material shall be processed to meet the acceptance criteria for disposal established
with the approval of the regulatory body. These criteria define the radiological,
mechanical, physical, chemical and biological properties of the waste. More
information on the requirements for long-term management of NORM residues is
given in Chapter 5.
Bulk minerals processing residues other than uranium mill tailings
4.30 Of the different residues produced by NORM activities, bulk residues
represent the greatest challenge, despite their relatively low specific activity. This is
particularly true in terms of long-term management, because of the large volumes
produced, and the presence of very long lived radionuclides and (often) other
hazardous substances, such as heavy metals. Such residues include phosphogypsum,
red mud from alumina processing and metaliferous tailings. The preferred
management option will depend on specific conditions at the site, the characteristics of
the NORM, the processes to be used, and the characteristics of the bulk residue.
Section 5 provides guidance on the siting, design, construction and operation of large
volume NORM residue management facilities.
o
Waste rock, mineralized waste rock and similar residues
o4.31 While the radiological hazards associated with waste rock and mineralized
waste rock are usually much less significant than those for bulk minerals processing
residues, non-radiological hazards will remain and are often more important when
considering the most appropriate management options. There are many possible
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options for managing waste rock and mineralized waste rock: the best option in
practice will depend on the particular mineralogy, radioactivity and chemical
reactivity of these wastes.
o4.32 Options for managing waste rock and mineralized waste rock include their use
as backfill materials in open pits and underground mines, and for construction at the
mine site. The need to cover mineralized waste rock with inert waste rock should be
taken into account. As with bulk minerals processing residues, the stability of piles of
waste rock, and their resistance to erosion and rainwater infiltration, should be
considered, to ensure that they do not result in unacceptable environmental impacts on
the water catchment area. Co-disposal of waste rock with tailings is a procedure that
can be considered for both underground and above ground disposal options in mining
situations however chemical compatibility of the comingled material should be
considered.
4.94.33 Some waste may be suitable for reincorporation into the original
environment by dilution back to activity concentrations comparable to the original
state. An example would be monazite sands being reincorporated uniformly into the
remediated workings of a minerals sands extraction operation.
o4.34 Waste rock can be divided into three broad categories:
Unmineralised waste: This generally represents waste rock that is geologically
distinct from the ore-body, for example sedimentary cover sequences above a
metamorphic host zone. This material in general has a radionuclide content
characteristic of typical background material, and well below levels of
regulatory significance. There are thus no radiological constraints on its
management or re-use.
Mineralised waste: This material usually exhibits radionuclide content
significantly above normal background levels, and may range up to near that of
ore, and so may or may not be of regulatory significance. Thus there may be
some constraints on the uses to which it may be put, or to the requirements for
long term storage or disposal.
Uneconomic mineralised material: This category is applicable to uranium or
thorium mining, and refers to material that has a uranium or thorium content
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that is, under present conditions, uneconomic to process. Such material may be
segregated so that should economic conditions change it could be processed, or
it might simply be included with mineralised waste. Its radionuclide content will
make it subject to regulatory control, and the uses to which it might be put will
be very limited and there will be significant radiological requirements on
storage and disposal.
It should be noted that all three categories may contain other (non-radiological)
contaminants that may affect re-use, storage or disposal requirements.
4.104.35 As noted above, there are no radiological constraints on unmineralised
waste rock, and it can be used either on-site (for construction purposes, impoundment
walls, mine backfill etc.) or off-site. The only significant requirement would be that
stringent procedures are in place to ensure that this material is properly segregated
from mineralized material and that it is not contaminated with material from the other
categories (or indeed ore).
4.114.36 Mineralised waste that is below regulatory concern should also be
available for use on- or off-site, however it should be demonstrated that the
mineralised waste is in fact below regulatory concern before it is used for these
purposes. Mineralised waste of regulatory concern can sometimes be used on-site, but
usually only in applications where it will not be a concern after rehabilitation. For
example it may be used for the walls of tailings impoundments, where it will
eventually be covered by inert material during rehabilitation. Uneconomic
mineralised material, if it is not processed during the later stages of the project has
very few potential uses, and will have significant requirements for storage or disposal.
Liquid waste
4.37 Liquid waste includes: process water; leaching fluids; rainfall runoff (from the
process plant area, waste management area, waste and ore stockpiles); seepage from
mill tailings, stockpiles and waste rock disposal areas; and mine water (for example,
groundwater which has entered open pits or underground mines). All liquid waste
should be managed on the basis of its quality and quantity, with account taken of
environmental and human health impacts, rather than on the basis of its sources.
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deleted as repeats
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o4.38 The water management system should be designed to minimize the volume of
contaminated water. This could be achieved, for example, by the diversion of clean
water away from sources of contamination, the reuse of wastewater in the process
circuit and dust suppression. Where appropriate, liquid wastes should be treated to
separate any solid NORM residues from suspension. These may then be managed
separately. Residual liquid may be treated to achieve discharge quality. Such a
procedure will optimize the waste management by minimizing the volume of liquid
waste to be treated. Water treatment may also be required for other reasons than
management of NORM residues.
Contaminated items
o4.39 Scrap items such as pipes, process vessels, pumps and machinery that have
been contaminated with NORM residues should be decontaminated where practicable,
in the interest of waste minimization. Items that remain contaminated, and any
residues from the decontamination process, should be managed as solid or liquid
NORM waste, as appropriate.
Manufactured items containing NORM
o4.40 Some manufactured items may contain significant concentrations of 238
U or
232Th series radionuclides e.g. some turbine blades and thoriated lenses. When such
items are designated as waste, they should be managed in accordance with the
procedures developed for NORM waste. Attention should also be paid to residues that
might be generated following re-use, repair or refurbishment of such items. This could
include cuttings, turnings and dust.
Low-volume Hhigher activity waste
o4.41 Some waste may comprise a relatively small volume but be of relatively higher
activity concentration; this is frequently the case for scale and sludges that may be
accumulate in pipes or process vessels. Such waste may be managed either in the
original or a modified form. Small volumes of unmodified waste may be sealed into
suitable containers and deposited in designated containments or special landfills, or
possibly placed deep within tailings management facilities that are destined for
closure. An option for some liquid residues may be borehole injection into suitable
geological formations.
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o4.42 After an appropriate treatment, a low volume, high activity waste may be
suitable for dispersion and dilution evenly throughout a large volume of low activity
waste.
Uranium mill tailings
o4.43 Of the different waste streams produced by uranium mining and milling
operations, uranium mill tailings (“tailings”) represent the greatest challenge,
particularly in terms of long term management, because of the large volumes produced
and their content of very long lived radionuclides and heavy metals. Because of their
large volume it is generally impractical to transport the tailings significant distances,
and so storage and disposal is constrained to the vicinity of the mine or processing
plant. The preferred management option for achieving the protection goals will
depend on specific conditions at the site, the characteristics of the ore body, the
specifics of the mining and milling processes, and the characteristics of the tailings.
The siting and design of tailings management facilities is an essential part of the
overall project design, and must be addressed from the earliest stages of project
development.
o4.44 Tailings contains all the radionuclides in the original ore, at concentrations
near their concentration in ore, with the exception of the uranium isotopes and their
immediate short lived decay products. Approximately 75% of the original
radioactivity present in the uranium ore is retained in the tailings. Tailings will thus
always be subject to regulatory control.
o4.45 There are very few options for re-use of tailings. Tailings, and particularly the
coarser size fractions may be of use as a component of mine fill.
o4.46 Tailings are usually discharged as a slurry containing about 20-50% solids into
a purpose built water retaining structure generally referred to as a “tailings
impoundment”. The design and construction of tailings impoundments are discussed
further in Section 5.
o4.47 The option of relocating tailings to a more favorable site for closure would not
normally be expected to provide the optimum strategy for management because of the
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large volumes of mining and milling waste that would be involved. However, if
relocation of the waste is being considered, care should be taken to factor into the
optimization all the significant radiological and non-radiological impacts that may be
introduced by the relocation itself, including issues relating to the transport of large
volumes of waste.
o4.48 Other disposal strategies for mill tailings that take different approaches for risk
assessment may be appropriate and they should be evaluated on a case-by-case basis.
For example, small quantities of mill tailings may be acceptable for disposal in
facilities designed for low- level radioactive waste, provided that the waste acceptance
criteria of the facility are complied with.
Heap leach waste
4.124.49 Heap leaching is a method successfully used for processing low-grade
uranium ore and typically involves the treatment of crushed or pelletized ore grade
material with acid or alkali (or bacteria) on large engineered pads on the surface.
Stope or block leaching of basted ore underground is also conducted. In the case of
uranium extraction, the uranium rich “pregnant” leach solutions are commonly passed
through an ion exchange columns or solvent extraction process to extract the uranium
for further processing. The uranium depleted “barren” leach solution is then
reconstituted and re-used.
4.134.50 Surface heap leach facilities require efficient containment, base liners
and leak detection systems to protect the surface environment and groundwater
resources.
4.144.51 Heap leach wastes consist of process liquids generated during
operation, the leached ore and potentially, ongoing release of solutions from
infiltration of the closed facility. During operation, waste process solutions can be
collected, treated and sent to adjacent evaporation ponds and/or injected into deep
disposal wells. In some cases, a separate residue storage dam may be required with
characteristics similar to those of a tailings dam.
Pag e o f 1 25 51
4.154.52 An important consideration is locating the heap leach pad to permit
ease of closure and isolation of the resulting residues in place, without relocation.
Heap flushing and neutralization may be conducted at closure.
In-situ leaching waste
4.164.53 In-situ extraction is only possible where the ore-body is contained in an
aquifer with suitable porosity and permeability to allow circulation of leach liquors
through it. Extraction is carried out by drilling a pattern of injection and extraction
wells into the ore-body and circulating leach liquor. The uranium is extracted from the
resulting “pregnant” solution by conventional solvent extraction or ion exchange
methods and the now barren solution is reconstituted and re-injected into the leaching
field. No conventional “tailings” are produced, but large volumes of liquid waste can
be generated.
o4.54 A small fraction of the leach liquor is bled off, in part to reduce the build-up of
undesirable impurities in the leach liquor, but largely to ensure that there is a greater
volume of fluid extracted than injected. This imbalance leads to a net inflow of fluid
into the mining area, which maximizes recovery of the leach solution and prevents
migration of contaminants from the mining process into the surrounding aquifer. This
bleed stream constitutes the largest volume of liquid waste from the process.
o4.55 Large volumes of liquid waste can also be generated where reconstitution of
the ore-body aquifer is required following completion of mining. This may require
flushing of the aquifer with several pore-volumes of uncontaminated water, and the
extracted water will contain radionuclides and other contaminants.
4.174.56 Smaller volumes of liquid water are generated from normal plant
operation, including wash-down of equipment and spillages.
4.184.57 Liquid waste can be disposed of by evaporation, or discharged into
aquifers or surface water-bodies. Aquifer injection can be too deep, and preferably
well-confined aquifers, or into shallower aquifers, typically the mining aquifer itself.
In cases where the aquifer is of good quality or discharge is into surface waterbodies,
treatment of the waste to remove radioactive and other contaminants will generally be
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required. However in some cases the disposal aquifer is of such poor quality that no
practical use can be foreseen for the water, and in such cases no treatment of liquid
waste (other than settling of entrained sediments) will be required before disposal.
4.194.58 In all cases of disposal of liquid waste into aquifers careful and detailed
hydrogeological modeling of the situation will be required. Such modeling is also
required for the mining process itself. Modeling will need to include the basic
hydrogeological parameters (permeability, porosity, hydrostatic heads and natural
aquifer flow, connections with other aquifers etc.) and chemical consideration of both
the groundwater and the host sediment.
4.204.59 As noted there are no convention tailings associated with in-situ
mining, but there is a range of other solid wastes generated. The largest amount of
(radiological) waste generally arises from the bleed stream treatment. If the bleed
stream is evaporated, evaporites can contain significant concentrations of
radionuclides. If the bleed is treated chemically to remove radionuclides, these will
usually be recovered in solid or slurry form.
4.214.60 The ore body aquifer may require pre-treatment prior to mining,
commonly to remove calcium, and the resulting precipitates can contain quite high
radium concentrations.
4.224.61 General radioactive solid wastes generated in processing include
process sludges and precipitates, filter media, and contaminated pipes, and equipment.
o In all cases of disposal of liquid waste into aquifers careful and detailed
hydrogeological modeling of the situation will be required. Such modeling is also
required for the mining process itself. Modeling will need to include the basic
hydrogeological parameters (permeability, porosity, hydrostatic heads and natural
aquifer flow, connections with other aquifers etc.) and chemical consideration of both
the groundwater and the host sediment.
o Monitoring of the disposal area (and again also the mining area) will be
required, principally to detect any unplanned migration of wastes or mining fluids
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from the injection sites. This is commonly accomplished by a ring of monitoring wells
drilled into the relevant disposal (or mining) aquifer, and where relevant, aquifers
above and below the injection points. Parameters monitored may be hydrogeological
(for example hydrostatic heads) or chemical (radionuclide or other contaminant
concentrations, conductivity, pH, redox etc.).
o Definitions of what parameter changes will be regarded as constituting
evidence of an excursion of waste or mining fluid beyond approved boundaries will
need to be determined by regulatory authorities before operations commence, together
with the remedial actions that will be required in the event of such an excursion being
detected. Remedial actions can include cessation of injection, either until conditions
stabilize or permanently, or extraction of liquid from the disposal area and either
disposal in the same area after treatment or disposal in some other area. .
o As noted there are no convention tailings associated with in-situ mining, but
there is a range of other solid wastes generated. The largest amount of (radiological)
waste generally arises from the bleed stream treatment. If the bleed stream is
evaporated, evaporites can contain significant concentrations of radionuclides. If the
bleed is treated chemically to remove radionuclides, these will usually be recovered in
solid or slurry form.
o The ore body aquifer may require pre-treatment prior to mining, commonly to
remove calcium, and the resulting precipitates can contain quite high radium
concentrations.
o General radioactive solid wastes generated in processing include process
sludges and precipitates, filter media, and contaminated pipes, and equipment.
Heap Leaching Waste
o
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REMEDIATION OF RESIDUE FACILITIES
o4.62 For a NORM contaminated site, remediation may be needed for the purpose of
protecting human health or the environment, or for the purpose of another land use.
Remediation is defined as an existing exposure situation and should be justified and
optimized.
o4.63 The major issues associated with sites contaminated through past practices
include the following:
Often little or no documentation of activities at the site is available;
It is difficult to assign responsibility for any remediation that may be required;
Characterization of the site can be difficult as in many cases the local
demographics have changed, and sites that were used or industrial activity are
now used for residential purposes;
Impact assessment can be complicated, for the same reasons that make site
characterization difficult.
o4.64 In dealing with a legacy site, a national remediation policy and strategy should
be developed, in which remediation of NORM residue should be taken into account.
Issues mentioned above should be well addressed in the remediation policy and
strategy.
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5. LIFE CYCLE MANAGEMENT OF NORM RESIDUES
INTRODUCTION
5.1 The management of bulk NORM residues needs to be planned when the mine,
processing plant or proposed industrial activity is first being developed and effectively
managed and controlled over the entire lifecycle of the facility. This section:
Provides guidance in the siting, design, construction, operation, closure and
decommissioningclosure of facilities to be used in the handling, treatment,
conditioning, storage and disposal of bulk NORM residues and the
management of small volumes of high activity wastes.
Discusses matters related to institutional controls including long -term
monitoring and access controls that may be needed to ensure the long -term
protection of people and environment at a facility containing NORM residues.
Treatment and Conditioning Considerations
5.2 The treatment and conditioning of NORM residues may be required to meet
established acceptance criteria for their storage and possible disposal. For example,
this may include treatment and conditioning to neutralize the residues to prevent
leaching of radiological and non-radiological contaminants. The conditioning may
also involve the chemical or physical alteration of the residues to reduce the hydraulic
conductivity of the residues or reduce the solubility of various contaminants.
Reference [10] provides guidance on the steps in predisposal management of
radioactive wastes that may be applicable to the treatment and conditioning of NORM
residues prior to long- term storage or disposal14
.
5.3 Where the management of bulk NORM residues includes eventual disposal, but
no disposal facility is available, specific assumptions should be made on the
requirements for the acceptance of the residues in a future repository in order to
provide guidance for its treatment, conditioning and storage. These assumptions
should be justified and agreed upon by the generator, the operator of the predisposal
management facility and the regulator.
14 Including Chapter 6 of IAEA Safety Guide, DS447:in preparation.
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SITING
5.4 Consistent with Requirement 17 of Ref [11], facilities for the management of
bulk NORM residues should be located and designed so as to ensure safety for the
expected operating lifetime of the facilities under both normal and possible accident
conditions.
5.5 The siting of facilities required for the management of bulk NORM residues
should take into consideration the source of the residues and their overall chemical
and physical properties, their relative radiological and non-radiological hazard and
their volume.
5.6 The optimum site for residue management facilities will take into account the
protection of human health and the environment as well as economic considerations.
The siting of residue management facilities should provide for the effective collection
and containment of the residue and should prevent the diversion of residues from the
site other than by means of authorized discharges or by the authorized removal of
regulatory control.
5.7 Criteria for siting and methods that could be used in a graded approach to the
siting of a facility for the long-term management of NORM residues can be found in
Refs [14], [15] & [16].
5.8 A preliminary evaluation of site characteristics should be made so as to identify
any restrictions, in terms of radiological and environmental factors, at each proposed
location, and to allow the selection of a small number of locations and possible
preliminary design concepts for which the impacts can then be evaluated in detail. The
final optimized choice of site obtained using the conceptual design for residue
management should be assessed and the resulting safety assessment, which might be
part of the environmental impact assessment, should be submitted to the regulatory
body for review. Section 6 provides further guidance on the approaches to conducting
safety assessments.
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5.9 In selecting the site for long term management of large volumes of NORM
residues, the important considerations in the optimization process that should be taken
into account, particularly in reducing the need for long term institutional controls after
closure, include the following:
(a) Climatology and meteorology;
(b) Geography, geomorphology, demography and land use;
(c) Structural geology and seismology;
(d) Geochemistry;
(e) Mineralogy;
(f) Surface water and groundwater hydrology;
(g) Flora and fauna;
(h) Archaeological and heritage issues;
(i) Natural background levels of radiation;
(j) Public acceptance issues.
5.10 In selecting the site for management of bulk NORM residues, consideration
should be given to the benefits of consolidating residues to limit the number of residue
management sites.
DESIGN AND CONSTRUCTION
5.11 Requirement 18 of Ref [10] states that: “Predisposal radioactive waste
management facilities shall be constructed in accordance with the design as described
in the safety case and approved by the regulatory body. Commissioning of the facility
shall be carried out to verify that the equipment, structures, systems and components,
and the facility as a whole perform as planned.” This requirement is equally
applicable to NORM residue management facilities.
5.12 The major design consideration for the management of bulk NORM residues is
the need to ensure proper containment and isolation of the residues and to control
releases of any contaminants. Good waste management practices should be followed
to the extent practicable and consistently with the requirements for radiological
protection, such that the design of the residue management facilities:
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(a) Maximizes the use of natural materials and natural barriers for
containment;
(b) Minimizes potential erosion and accidental release of solids outside of
containment by maximizing the placement of residue material below ground
level, or in some cases under water;
(c) Minimizes the surface area of the area impacted by the facility
(d) Minimizes the impact on the surrounding environment during
operations and after closure;
(d) Minimizes the need to retrieve or relocate the residue at closure;
(e) Minimizes the need for surveillance, maintenance and controls during
operations and post-closure; and
(f) minimizes the number of residue management sites through
consolidation of residues.
5.13 In addition when designing a facility for the long term management of NORM
residues, due consideration should be given to the:
(a) sSite characteristics as detailed in paragraph 5.9,
(b) rResidue characteristics including volume, chemical, physical and radiological
properties
(c) rResidue conditioning including neutralization, precipitation, thickening and
evaporation
(d) pPotential for retrieval of NORM residues either for relocation or re-processing
for further resource extraction;
(e) mManagement of liquids including seepage collection and treatment;
(f) rRadiation protection measures which may include shielding, containment, and,
radon and dust control;
(g) aAccess control including site access and the control of movement between
radiation zones and contamination zones;
(h) iInspection of the residues and their containment;
(i) vVentilation in surface facilities including the filtration of airborne releases of
radioactive material;
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(j) eEnvironmental monitoring of the facility including ground water well
installations, water and air sampling stations downstream of any effluent or
airborne releases
(k) Maintenance work and eventual decommissioningclosure
(l) Re-vegetation;
(m) Long term stability and erosion control (e.g. dams, berms, slopes, covers) in
relation to natural weathering processes and extreme natural events (e.g.
flooding, droughts, tornadoes, earthquakes)
Control of inadvertent intrusion by people, plants or animals.
(n) Bulk NORM Residues
5.14 Facilities for the long -term management of bulk NORM residues should have
sufficient capacity to process all such residues generated and, where the facilities are
intended to provide storage only, the storage capacity should be sufficient to account
for uncertainties in the availability of facilities for final disposal. The capacity should
also be sufficient to process residues that may arise from incidents and accidents, and
for the future decommissioning and dismantling of the support facilities.
5.15 The facility design should take into consideration the potential effects that the
residues and the environmental conditions may have on the capabilities of the facility
to provide long term containment and isolation, and to control the release of
contaminants into the environment. Processes and properties that should be
considered include, for example, drainage and water management, the acid generating
potential of the residues, the effect of extreme changes in climate including
precipitation and temperature and extreme external events such as earthquakes, floods,
tornadoes, hurricanes, typhoons, forest fires, etc.
5.155.16 To conform to the principles for managing radioactive waste [2], access
to and dispersion in the environment of the hazardous constituents of the tailings
should be restricted for long periods into the future. Preference should always be given
to designs that minimize the requirement for application of institutional controls.
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5.16 Drainage and water management are major considerations in the design of a
facility for the management of bulk residues. Installed drainage systems can help in
terms of consolidating bulk residues before closure and reducing excess pore water
pressure. In the case of a surface impoundment or a pit, this could be achieved by the
installation of a drainage system prior to or during the emplacement of bulk residue, or
by the use of wicks driven into the bulk residue after emplacement. The base and cap
of the impoundment should be built of a material of low permeability, if possible
using material of natural origin. In other cases, uncontrolled drainage is a problem that
needs to be addressed, for example by the use of appropriate liners. The addition of a
stabilizing agent (such as cement) to the bulk residue prior to its deposition can
significantly reduce the permeability of the bulk residue mass, thus retarding the
transport of contaminants and binding any pore water.
5.17 Soil moisture can also significantly affect radon transport and release from the
residue containment facility. Moist and saturated soil conditions in cover materials
tend to slow the rate of diffusion to the surface. The diffusion coefficient through a
saturated soil may be several orders of magnitude smaller compared with that of a dry
soil. In certain cases, a water covering or saturated cover layer may serve as an
effective radon barrier. In dry environments, a different approach is required.
5.18 Factors that influence the selection of cover material include climate, availability
of materials, properties of the residue, regulatory requirements and other site-specific
needs or issues (e.g. generation of acid rock drainage, water infiltration, erosion).
5.19 Cover materials that have been effective in reducing radon emissions include
water, earthen materials, geosynthetics such as geomembranes and geosynthetic clay
liners, and evapotranspirative barriers. Simple covers may contain one type of
material; however, combinations of different materials are often required.
5.20 A conventional cover system designed to limit infiltration and radon emissions
from an above ground impoundment, may have a lateral drainage layer consisting of
either coarse sand or gravel, to limit head buildup above a low permeability clay layer,
and a top layer of durable rock for erosion protection. Depending on the climate and
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environment, this rock may also support a vegetative cover for erosion control,
stabilization and limiting infiltration.
5.21 The decision on which drainage/dewatering approach to take should be
optimized, so as to match barrier characteristics with available site conditions. For
disposal in underground mines, the increased structural integrity from adding concrete
to the bulk residue may allow adjacent mining to continue. Prior to adopting this
strategy, possible chemical interactions between the stabilizing agent, the bulk residue
and the host rock should be carefully investigated.Sub-Surface Disposal
5.22 In addition to the disposal of bulk residue in above ground impoundments, open
pits and underground mine voids, there are other options for waste management, such
as the deposition of bulk residue in lakes. However, options such as this should
involve careful study and evaluation. Preference should always be given to designs
that minimize the requirement for application of institutional controls.
5.23 It is possible that the underground disposal of mine bulk residue at a particular
site may not be feasible, either due to site-specific problems for which no engineering
solutions can be identified, or due to prohibitive cost. In such cases, the use of
engineered surface impoundments may be the only viable option and should be
considered.
5.17 Practical engineering solutions can be identified for some below-ground bulk
residue disposal facilities. For example, if the hydraulic conductivity of the bulk
residue mass is greater than that of the surrounding host rock, the use of a highly
permeable envelope surrounding the bulk residue should be considered as a means of
diverting groundwater around the bulk residue. In the case of a small and confined
aquifer intersecting a pit or underground mine wall, localized grouting should be
considered.
5.245.18 In the case of disposal in underground mines, the increase in structural
integrity gained by using concrete with the tailings mass may allow mining to be
continued immediately adjacent to the tailings. Prior to adopting this strategy, possible
chemical interactions between the stabilizing agent, the tailings and the host rock
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should be carefully investigated to ensure that the transport of contaminants would not
be enhanced at some time in the future.
5.19 The successful closure of an in-pit emplacement may be achieved either by
backfilling and capping with natural materials or by the establishment of a permanent
water pond over the bulk residue. The latter option should include the application of a
low permeability cover for the waste to reduce contact with the pond water. The sub-
surface conditions should be fully investigated in order to ensure that the hydraulic
pressure over the backfilled pit will not result in future groundwater contamination.
5.25 Surface Disposal
5.20 The underground disposal of mine bulk residue at a particular site may not be
feasible, either due to site-specific problems for which no engineering solutions can be
identified, or due to prohibitive cost. In such cases, the use of engineered surface
impoundments may be the only viable option and should be considered.
5.265.21 For above ground impoundments, the bulk residue can be contained
within low permeability, engineered structures that reduce seepage. An above ground
closure option would usually necessitate greater institutional control than an
underground disposal option. Monitoring and maintenance programprogrammes
should be implemented during the operational, closure and post-closure phases. Thus
the above ground approach would be likely to entail lower initial (capital) costs but
higher ongoing (operating) costs.
5.27 The relocation of bulk residue to a more favorable site for closure would not
normally be the optimum management strategy because of the large volumes involved.
However, if relocation is being considered, all the significant radiological and non-
radiological impacts associated with relocation, including impacts relating to the
transport of large volumes of waste, should be assessed.
5.28 Other disposal strategies for bulk residues may be appropriate, and they should
be evaluated on a case-by-case basis.
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5.295.22 The containment walls may be entirely constructed above grade, or a
small valley may be utilized. In this latter case it is essential that any run-off from
rainfall be diverted around the tailings repository area. The tailings impoundment is
generally the final repository for the tailings, although on occasion the tailings may
later be removed to another site (typically the worked out pit) for final disposition.
Alternatively, tailings impoundments are made from former open pit mines, where
available, or purpose-built pits. Other options, such as discharge to the bed of a lake,
exist as alternatives. However, they are rarely the preferred option and may not be
acceptable to regulators or the public. In any scenario, a safety case which
demonstrates protection of workers, the public and the environment should be
required..
5.23 The design of a facility for the management of tailings should incorporate
drainage systems to consolidate tailings before closure and to reduce excess pore
water pressure. Removal of excess water from the tailings is generally important, both
to reduce the potential for seepage of tailings liquor from the structure, and to allow
the tailings to consolidate to produce a firm mass which will bear the weight of
machinery during rehabilitation. This may be achieved by deposition in thin layers,
with each section being allowed to drain and dry by evaporation before the next layer
is deposited. Alternatively tThe excess liquor can be decanted and disposed of as a
liquid waste as described elsewhere. Alternatively, this could be achieved by the
installation of a drainage system prior to or during the emplacement of tailings, or by
the use of wicks driven into the tailings after emplacement.
5.30
5.24 To conform to the principles for managing radioactive waste [2], access to and
dispersion in the environment of the hazardous constituents of the tailings should be
restricted for long periods into the future. The base and cap of the impoundment
should be built of a material of low permeability, if possible using material of natural
origin. Uncontrolled drainage is a problem that needs to be addressed, for example by
the use of appropriate liners. The addition of a stabilizing agent (such as cement) to
the bulk residue prior to its deposition can significantly reduce the permeability of the
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bulk residue mass, thus retarding the transport of contaminants and binding any pore
water.
5.31
5.25 The design of a facility for the management of tailings should incorporate
drainage systems to consolidate tailings before closure and to reduce excess pore
water pressure. In the case of a surface impoundment or a pit, this could be achieved
by the installation of a drainage system prior to or during the emplacement of tailings,
or by the use of wicks driven into the tailings after emplacement. The base and cap of
the impoundment should be built of a material of low permeability, if possible using
material of natural origin. The addition of a stabilizing agent (such as cement) to the
tailings immediately prior to their deposition has the potential to reduce significantly
the permeability of the tailings mass, thus retarding the transport of contaminants and
binding any pore water. However, in certain cases, a confined, water covering in a pit
may possess excellent characteristics as a radon barrier, thereby obviating the need to
perform dewatering to any significant degree. Decommissioning Closure plans, which
rely on water coverings must consider the ability of the cover to be both present and
passively maintained over the long term. The decision on which drainage/dewatering
approach to take should be optimized, so as to match barrier characteristics with
available site conditions.
Radon Barriers
5.26 Soil moisture can also significantly affect radon transport and release from the
residue containment facility. Moist and saturated soil conditions in cover materials
tend to slow the rate of diffusion to the surface. The diffusion coefficient through a
saturated soil may be several orders of magnitude smaller compared with that of a dry
soil. In certain cases, a water covering or saturated cover layer may serve as an
effective radon barrier. In dry environments, a different approach is required.
5.27 Factors that influence the selection of cover material include climate, availability
of materials, properties of the residue, regulatory requirements and other site-specific
needs or issues (e.g. generation of acid rock drainage, water infiltration, erosion).
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5.28 Cover materials that have been effective in reducing radon emissions include
water, earthen materials, geosynthetics such as geomembranes and geosynthetic clay
liners, and evapotranspirative barriers. Simple covers may contain one type of
material; however, combinations of different materials are often required.
5.325.29 A conventional cover system designed to limit infiltration and radon
emissions from an above ground impoundment, may have a lateral drainage layer
consisting of either coarse sand or gravel, to limit head buildup above a low
permeability clay layer, and a top layer of durable rock for erosion protection.
Depending on the climate and environment, this rock may also support a vegetative
cover for erosion control, stabilization and limiting infiltration.
5.30 The decision on which approach to take should be optimized so as to match
barrier characteristics with available site conditions. In the case of disposal in
underground mines, the increase in structural integrity gained by using concrete with
the tailings mass may allow mining to be continued immediately adjacent to the
tailings. Prior to adopting this strategy, possible chemical interactions between the
stabilizing agent, the tailings and the host rock should be carefully investigated to
ensure that the transport of contaminants would not be enhanced at some time in the
future.
5.31 Other disposal strategies for bulk residues may be appropriate, and they should
be evaluated on a case-by-case basis. The relocation of bulk residue to a more
favorable site for closure would not normally be the optimum management strategy
because of the large volumes involved. However, if relocation is being considered, all
the significant radiological and non-radiological impacts associated with relocation,
including impacts relating to the transport of large volumes of waste, should be
assessed.
Higher activity low volume waste
5.32 Some waste may comprise a relatively small volume but be of higher activity
concentration. This may be the case for a wide range of materials including:
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Scales and sludge that may be accumulate in pipes or process vessels in oil and
gas production, coal production with radium rich inflow water, and rare earth
production;
Anode slimes from electro-wining processes;
Precipitated smelting dusts and slags;
Rare earth extraction residues;
Contaminated equipment, process filters.
5.33 These precipitates, scales and residues are mostly enhanced in specific
radionuclides and to levels that depend more on chemical conditions than on the
original ore grade or feedstock radionuclide contents.
5.34 Such waste may be managed either in the original or in a modified form. There
is a range of disposal options for these materials, depending on the nature of the
material and its waste classification [17]. The radionuclide content may necessitate
management of these materials as Low Level Waste or Intermediate Level Wastes.
Some wastes may be suitable for interim storage to allow for decay of short-lived
radionuclides such as most 210
Pb and/or 210
Po.
5.35 After an appropriate treatment, a low volume, high activity waste may be
suitable for dispersion and dilution evenly throughout a large volume of low activity
waste.
5.36 Small volumes of unmodified waste may be sealed into suitable containers and
deposited in designated containments, special landfills or specially engineered
boreholes [18], or possibly placed deep within tailings dams that are destined for
closure. An option for some liquid residues may be borehole injection into suitable
geological formations.
Passive Design
5.33
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5.345.37 The principle that undue burdens should not be placed on future
generations leads to the conclusion that a passive approach to design for closure is
preferable to a design that needs significant and ongoing maintenance. Such a passive
approach is generally best achieved by disposal in pits excavated specifically for this
purpose, in mined out pits or in underground mine voids in geologically stable sites.
This option may eliminate or significantly reduce the need for surface disposal of
tailings. Disposal of waste below ground level is typically less susceptible to surface
erosion of material to the environment and to intrusion, and generally necessitates less
maintenance than surface tailings impoundments. Closure entails sealing the openings
to the underground disposal facility, thereby isolating it from the surface.
5.355.38 For the disposal of underground tailings underground, provided that the
probabilities of geological disturbance to the site and of human intrusion into the site
are deemed to be sufficiently low, no further controls may be necessary beyond
archiving details of the location and characteristics of the waste and monitoring the
site for a limited period.
5.365.39 The passive approach to design should be considered an option more
likely to be realistic in optimizing radiological protection in new waste management
facilities. For example, where tailings can be deposited in mined out pits, passive
designs may be partially or even fully realizable and may provide the basis for the
optimum strategy.
5.37 It is possible that the underground disposal of mine tailings at a particular site
may not be feasible, owing either to site specific problems for which no engineering
solutions can be identified or to prohibitive cost. In such cases, the use of engineered
surface impoundments may be the only viable option and should be considered.
5.38 Practical engineering solutions can be identified for some site specific problems
associated with below ground level tailings disposal facilities. For example, if the
hydraulic conductivity of the tailings mass is greater than that of the surrounding host
rock, the use of a highly permeable envelope surrounding the tailings should be
considered as a means of diverting groundwater around the tailings. In the case of a
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small and confined aquifer intersecting a pit or underground mine wall, localized
grouting should be considered.
5.395.40 The desired passivity in the closure of an in-pit emplacement may be
achieved either by backfilling and capping with natural materials or by the
establishment of a permanent water pond over the tailings. The latter option should
include the application of a low permeability cover for the waste to reduce contact
with the pond water. The subsurface conditions should be fully investigated in order to
gain sufficient understanding to be able to ensure that the hydraulic pressure over the
backfilled pit will not result in problems of groundwater contamination arising in the
future.
5.40 As regards options involving the management of tailings in above ground
impoundments, the tailings should be contained within low permeability engineered
structures so as to reduce seepage. An above ground closure option would usually
necessitate having greater institutional control than an underground disposal option.
Monitoring and maintenance programs should be implemented during the operational,
closure and post-closure phases. This approach would entail lower initial costs but
higher continuing costs.
5.41 Detailed engineering design of the residue management facilities can proceed
after the site and the conceptual design have been approved by the regulatory body. At
this stage, a further safety assessment, including optimization of protection, should be
performed. Figure 1 shows an example of the regulatory process for new facilities for
the management of NORM residues. If significant changes are made to the design of
the residue management facilities at any stage, a further safety assessment, including
optimization of protection, should be undertaken.
5.42 The detailed design should be supported, where appropriate, by fieldwork and
laboratory or pilot plant studies and by radiological and environmental impact
assessments. The design should include a waste management plan covering the
management of residues, residue treatment and conditioning and any applicable
effluent treatment, seepage controls and operational monitoring.
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5.43 A preliminary closure plan should be prepared during the design of the facilities,
which, at a conceptual level, identifies and ranks the available options for their closure
according to the results of the safety assessment and the optimization of protection. It
should also specify the financial provisions necessary for the preferred option. The
preliminary closure plan should be submitted to the regulatory body for approval.
5.44 When considering the design for long term control of facilities for bulk NORM
residues, passive institutional controls are preferable to a design that needs significant
and ongoing maintenance. This is generally best achieved by disposal in pits
excavated specifically for this purpose, in mined-out pits or in underground mine
voids in geologically stable sites. This option may eliminate or significantly reduce the
need for surface disposal of bulk residue. Disposal of waste below ground level is
typically less susceptible to surface erosion resulting in possible breach of a
containment and release of waste to the environment. Furthermore, below ground
containments are less susceptible to intrusion, and generally require less maintenance
than surface bulk residue impoundments. Closure entails sealing the openings to the
underground disposal facility, thereby isolating it from the surface.
5.45 For the disposal of bulk residue underground, provided that the probabilities of
geological disturbance and human intrusion are deemed sufficiently low, no further
controls may be necessary beyond the keeping of appropriate records of the location
and characteristics of the waste for a defined period.
5.46 The passive design approach is more likely to be a successfully realized in new
waste management facilities. For example, where bulk residue can be deposited in
mined out pits, passive designs may be partially or even fully attainable and may
provide the basis for the optimum strategy.
5.475.44 Unlike surface buildings where many corrections may still be made
during the commissioning stage, the construction of storage and disposal facilities for
large volume NORM residues are such that correction of major deficiencies will be
cost prohibitive and in some cases practically impossible. As a result, for long term
management facilities for large volume NORM residues, it is important that effective
verification and quality control measures are in place to ensure that the construction of
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any engineered structures such as dams, berms, engineered liners, compacted layers
meet the design specifications. The quality control programprogramme will also
require testing of construction materials (e.g. tills and clay) to ensure they meet the
design specifications.
5.485.45 The construction quality control programprogramme should be
established at an early stage in the design process as an intrinsic part of the project to
facilitate its effective implementation. Arrangements should be established to cover:
(a) Specification of tests to be carried out (test objectives, design criteria to be met);
(b) Provision and approval of documentation;
(c) Responsibilities;
(d) Control of test work;
(e) Recording and review of test results;
(f) Interaction with the regulatory body;
5.495.46 Commissioning of the NORM residue management facilities should
follow similar processes and protocols that would apply to any waste management
facility15
.
OPERATION
5.505.47 Requirement 18 of Ref [4] states that: The disposal facility shall be
operated in accordance with the conditions of the licence and the relevant regulatory
requirements so as to maintain safety during the operational period and in such a
manner as to preserve the safety functions assumed in the safety case that are
important to safety after closure.
5.515.48 The facilities should be operated in accordance with the residue
management strategy, the safety assessment, the authorization or license, and a residue
management plan. The residue management plan should describe in detail all aspects
of the management of the residues. In addition, the plan is a key component of the
management system and should include provision for:
15 DS447 (in preparation) also provides further guidance on the approach to commissioning.
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Detailed and documented procedures for operation, maintenance, monitoring
and safety;
Training of personnel in the implementation of the procedures;
Adequate surveillance and maintenance of all the structures, systems and
components of the facility that are important to safety;
A system of controlled and supervised areas and clearance procedures for
materials removed from the site;
Timely submissions to the regulatory body of inspection reports, monitoring
results and reports on unusual occurrences;
The development and exercise, where appropriate, of contingency plans for
potential failures of the residue management facilities that may result in
significant increased risk to human health or the environment.
5.525.49 Measures should be taken during operations, and consistently with the
safety assessment, to limit the amount and rates of release to the environment of
contaminants in liquid and airborne effluents. Measures should be used to ensure that
residues remain under proper control so that their potential misuse is avoided.
Releases of radon or radioactive dusts into the atmosphere and of radium and other
radionuclides into surface water and groundwater by surface runoff or leaching from
residues should be minimized.
5.535.50 Facilities for long-term management of NORM residues should be
operated in accordance with written procedures prepared by the operating
organization. These documents and their updates should be prepared in cooperation
with the organizations responsible for the design of the facility. However, the
operating organization is responsible for ensuring that the procedures are prepared,
reviewed, approved and issued appropriately. These procedures should, as a minimum,
be such as to ensure compliance with the operational limits and conditions for the
facility and, more generally, with the safety assessment.
5.545.51 Instructions and procedures should be prepared for normal operations
of the facility and anticipated operational occurrences. Instructions and procedures
should be prepared so that the designated responsible person can readily perform each
action in the proper sequence. Responsibilities for approval of any deviations from
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operating procedures that may be necessary for operational reasons should be clearly
specified [21].
5.555.52 The maintenance and modification of any item of equipment, process
or document of the facility should be subject to specified procedures. These
procedures should be subject to authorization before they are implemented. The
procedures should describe the categorization of the modification in accordance with
its safety significance. Depending upon the safety categorization, each modification
will be subject to varying levels of review and approval by management of the facility
and the regulatory body.
5.565.53 The maintenance or modification of any item of equipment should be
appropriately recorded and documented together with its commissioning test results.
The documents should be revised immediately after completion of the maintenance or
modification.
5.575.54 Operating procedures should be developed for containment systems in
the facility (e.g. ventilation and filtration systems) to provide for their monitoring.
Such monitoring should be such that the operating organization will be able to
determine when corrective actions are necessary to maintain safe operational
conditions.
5.585.55 In addition to providing operating procedures and contingency
procedures as described above, the operating organization should also develop an
emergency plan. The plan should consider events such as the following:
Catastrophic equipment failures;
Loss of safety related facility process systems such as supplies of electricity,
process water, compressed air and ventilation;
Fires leading to the damage of items important to safety;
Natural events, such as extreme weather conditions and extreme natural events
such as flooding or earthquakes;
5.595.56 Operating experience and events at the facility and reported by similar
facilities should be collected, screened and analyzed in a systematic way. Conclusions
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should be drawn and implemented by means of an appropriate feedback procedure.
Any new standards, regulations or regulatory guidance should also be reviewed to
check for their applicability for safety at the facility.
5.605.57 Operational limits and conditions should be developed on the basis of
the following:
Design specifications and operating parameters and the results of
commissioning tests;
The sensitivity of items important to safety and the consequences of events
following the failure of items, the occurrence of specific events or variations in
operating parameters;
The accuracy and calibration of instrumentation equipment for measuring safety
related operating parameters;
Consideration of the technical specifications for each item important to safety
and the need to ensure that such items continue to function in the event of any
specified fault occurring or recurring;
The need for items important to safety to be available to ensure safety in
operational states including maintenance;
Specification of the equipment that should be available to enable a full and
proper response to postulated initiating events or design basis accidents;
The minimum staffing levels that needs to be available to operate the facility
safely.
5.615.58 Operational limits and conditions form an important part of the basis on
which operation is authorized and as such should be incorporated into the technical
and administrative arrangements that are binding on the operating organization and
operating personnel. Operational limits and conditions, which result from the need to
meet legal and regulatory requirements, should be developed by the operating
organization and subject to approval by the regulatory body as part of the license
conditions. The operating organization may wish to set an administrative margin
below the operational limits as an operational target to remain within the approved
limits and conditions.
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5.625.59 The aim of operational limits and conditions is to manage and control
the hazards associated with the facility. Operational limits and conditions should be
directed towards:
Preventing situations that might lead to the unplanned exposure of workers and
the public to radiation;
Mitigating the consequences of any such events, if they were to occur.
5.635.60 Personnel directly responsible for operation of the facility should be
thoroughly familiar with the facility’s operating procedures and the operational limits
and conditions to ensure compliance with their provisions. Systems and procedures
should be developed in accordance with the approved management system and
operating personnel should be able to demonstrate compliance with the operational
limits and conditions.
5.645.61 Operational limits and conditions should be kept under review and may
also have to be revised as necessary in accordance with the national regulatory
framework for the following reasons:
In the light of operating experience;
Following modifications made to the facility and the type of radioactive waste;
As part of the process of periodically reviewing the safety case (including as
part of periodic safety review) for the facility;
If there are changes in legal or regulatory conditions.
5.655.62 As a result of operating experience, technological progress or changes,
corresponding changes to operational conditions may be necessary. Such changes
should be justified through safety assessment and should be subject to approval by the
regulatory body.
5.665.63 Operation of a facility for the long term management of NORM
residues should include an appropriate programme of maintenance, inspection and
testing of items important to safety, i.e., structures, systems and components. Safe
access should be provided to all structures, systems, areas and components requiring
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periodic maintenance, inspection and testing. Such access should be adequate for the
safe operation of all necessary tools and equipment and for the installation of spares.
5.675.64 An operational radiation protection programme should be put in place
that ensures that areas of the facility are classified according to the radiation levels and
that access control is in place in accordance with the level of classification. It should
cover the monitoring of radiation levels in the facility and should include provision to
ensure that personnel working in the facility are provided with appropriate dosimetry.
A programme of work planning should also be put in place to ensure that radiation
exposure is kept as low as reasonably achievable.
5.685.65 The potential radiological impacts of incidents and accidents should be
assessed by the operating organization and reviewed by the regulatory body. Provision
should be made to ensure that there is an effective capability to respond to incidents
and accidents. Considerations should include the development of scenarios of
anticipated sequences of events and the establishment of emergency procedures and an
emergency plan to deal with each of the scenarios, including checklists and lists of
persons and organizations to be alerted.
5.695.66 Emergency response procedures should be documented, made available
to the personnel concerned and kept up to date. The need for exercises should be
assessed. If there is such a need, exercises should be held periodically to test the
emergency response plan and the degree of preparedness of the personnel. Inspections
should be performed regularly to ascertain whether equipment and other resources
necessary in the event of an emergency are available and in working order.
5.705.67 In some instances, the NORM residues may result in high radiation
exposures situations. For example, this may occur near stockpiles of active materials,
where radium scales or high activity thorium based residues are present, or where
dusts and fume are present. Where high radiation exposure activities are involved,
radiation doses should be kept as low as reasonably achievable by the use of features
such as remote handling techniques for operations and maintenance and by
establishing limits on the activities and dose rates for the items to be removed from
highly contaminated or radioactive areas to less contaminated or radioactive areas.
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When manual maintenance operations are foreseen, adequate protection should be
provided, for example, by the decontamination of equipment and the use of temporary
or permanent shielding.
CLOSURE
5.68 A preliminary plan for the decommissioning and dismantling of an operation’s
facilities, and the closure of a NORM residue management facility should be drawn up
at the design stage [4]. This plan should be reviewed and updated, as necessary,
throughout the operational life of the facility. Prior to closure, the operator should
prepare a final closure plan, and submit this to the regulatory authority for approval.
5.69 An important part of the planning for closure is confirming that the conceptual
design of the NORM residue management facility is still valid. The conceptual model
provides a description of the components of the system and the interactions between
these components. It also includes a set of assumptions concerning the geometry of the
system and the chemical, physical, hydrogeological, biological and mechanical
behavior of the system, consistent with the information and knowledge available.
5.71
5.725.70 The final closure plan should address at least the following elements:
Long-term monitoring and surveillance;
Remediation;
Disposition of NORM residues, including those arising from decontamination
of the facility;
Disposal of waste;
The potential for recycling or new use for residues, plant and items containing
or contaminated by NORM;
An assessment of the post-closure risks to individuals and the environment;
Final radiation survey of the site.
5.735.71 Following regulatory body approval, the operator should implement the
plan. Once closure has been achieved, the operator should make an assessment of the
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success of the work against the agreed closure criteria. The regulatory body should
undertake an assessment for compliance with the approved closure criteria. Once
compliance has been achieved and confirmed by the regulatory body the site may be
approved for release from regulatory control, with or without ongoing institutional
control.
5.745.72 Once any part of the waste management facilities is no longer needed,
it should be closed to the extent practicable during operations (e.g. closure of a waste
rock pile).
5.755.73 At a time agreed upon with the regulatory body, and at least five years
before the anticipated closure date, the operator should submit a final closure plan for
regulatory approval. The objectives of closure should be to ensure that the waste
management facilities are left in a condition that will ensure their continued
compliance with the requirements for the protection of human health and the
environment.
5.765.74 The closure plan should be harmonized to the extent practicable with
the schedule for decommissioning surface structures and equipment. The
decommissioning of these structures and equipment has been addressed in other IAEA
safety standards [1, 10]. The management of waste from decommissioning activities
may be combined with management of the closure of the facilities for the disposal of
waste from operations, provided that this will not introduce problems, for example, by
creating voids in the tailings mass. This is most effectively accomplished when
decommissioning is conducted prior to, or at the same time as, closure.
5.775.75 The primary goal of the disposal of radioactive waste is the protection
of people and the environment in the long term, after the disposal facility has been
closed. In this period, migration of radionuclides to the accessible biosphere,
dispersion of radionuclides into the accessible biosphere and the consequent exposure
of people may occur. This is a consequence of the slow degradation of engineered
components and the slow transport of radionuclides from the facility by natural
processes. Discrete events may lead to an earlier or greater release. Such events could
be of either natural or human origin.
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5.785.76 In the design of a facility for the long term management of NORM
residues consideration should be given to the eventual decommissioning closure of the
facility, as regards both facilitating the decommissioningclosure activities and keeping
the generation of radioactive waste to the minimum practicable,
5.795.77 A final goal of decommissioning closure should be to enable the partial
or complete removal of regulatory control from the facility. The safety objective is to
site, design, construct, operate and close a NORM residue management facility so that
protection after its closure is optimized, social and economic factors being taken into
account. A reasonable assurance also has to be provided that doses and risks to
members of the public in the long term will not exceed the dose constraints or risk
constraints that were used as design criteria.
5.805.78 A set of performance obectivesobjectives should be established for
assessing the success and overall effectiveness of the decommissioningclosure
activities. These performance objectives should hasve been initially established to
support the design of the facility and set engineering controls on the operations.
5.815.79 Since NORM residues can present a long term radiological risk,
performance obectivesobjectives for radiation protection should be established using
dose criteria that are based on regulatory limits for exposures to the public. These can
include the following [Ref 4]:
The dose limit for members of the public for doses from all planned exposure
situations is an effective dose of 1 mSv in a year. This and its risk equivalent are
considered criteria that are not to be exceeded in the future.
To comply with this dose limit, a disposal facility (considered as a single
source) is so designed that the calculated dose or risk to the representative
person who might be exposed in the future as a result of possible natural
processes16
affecting the disposal facility does not exceed a dose constraint of
0.3 mSv in a year or a risk constraint of the order of 10–5
per year17
.
16 Natural processes include the range of conditions anticipated over the lifetime of the facility and
events that could occur with a lesser likelihood. However, extremely low probability events would be
outside the scope of consideration. 17
Risk due to the disposal facility in this context is to be understood as the probability of fatal cancer
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In relation to the effects of inadvertent human intrusion after closure, if such
intrusion is expected to lead to an annual dose of less than 1 mSv to those living
around the site, then efforts to reduce the probability of intrusion or to limit its
consequences are not warranted.
If human intrusion were expected to lead to a possible annual dose of more than
20 mSv to those living around the site, then alternative options for waste
disposal are to be considered, for example, disposal of the waste below the
surface, or separation of the radionuclide content giving rise to the higher dose.
If annual doses in the range 1–20 mSv are indicated, then reasonable efforts are
warranted at the stage of development of the facility to reduce the probability of
intrusion or to limit its consequences by means of optimization of the facility’s
design.
Similar considerations apply where the relevant thresholds for deterministic
effects in organs may be exceeded.
5.825.80 Disposal facilities for NORM residues may serve the additional
purpose of a repository for NORM contaminated materials which that may result from
routine operations or the dismantling of site facilities during decommissioning.
Decommissioning anCd closure design must consider comingling of materials from
various waste streams.
5.835.81 Decommissioning Closure of facilities for the long term management
of NORM residues comprises:
Design considerations and early decommissioningclosure planning;
Preparation and approval of the final decommissioningclosure plan;
The actual conduct of decommissioningclosure;
The management of waste resulting from closure decommissioning activities;
Release of the site for unrestricted or restricted use.
5.845.82 The key elements that should be considered for the decommissioning of
facilities associated with the long term management of NORM residues:
or serious hereditary effects.
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The selection of a decommissioning option in which the radionuclides in the
residual waste, technical factors, costs, schedules and institutional factors are
taken into account;
The development of a decommissioning plan;
The specification of the critical tasks involved in their decommissioning; in
particular decontamination, dismantling, demolition, surveillance and
conducting a final radiological survey;
The management functions important for their decommissioning, such as
training, organizational control, radiological monitoring, planning and the
control of waste management, physical protection, safeguards and quality
assurance.
5.855.83 Both the design and operational aspects that will have an influence on
decommissioning safety (e.g. the chemical processes or mechanical processes
involved) should be duly considered so as to facilitate the eventual decommissioning
of a facility. The design considerations for decommissioning and the decommissioning
measures should be consistent with the hazards expected to be associated with the
facility.
5.865.84 An initial version of the decommissioning plan should be prepared
during the design of the facility.
5.875.85 During the operation of the facility, the initial decommissioning plan
should be periodically reviewed and updated and should be made more comprehensive
with respect to:
Technological developments in decommissioning;
Possible human induced accidents and other incidents and natural events;
Modifications to systems and structures affecting the decommissioning plan;
Amendments to regulations and changes in government policy;
Cost estimates and financial provisions.
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5.885.86 Dismantling and decontamination techniques are required to be chosen
such that generation of waste and airborne contamination are minimized and
protection of workers and the public is optimized.
5.895.87 Before a site is released, for example for unrestricted use, it should be
monitored and, if necessary, cleaned up. A final survey should be performed to
demonstrate that the end point criteria, as established by the regulatory body, have
been met.
REMOVAL OF REGULATORY CONTROL
5.905.88 Prior to the release of material, equipment, structures or the site to the
public for general or restricted use, regulatory criteria should be established, such as
those for:
4.2 Removal of material, equipment, structures, soil and rock, from regulatory
control;
4.2 Authorized reuse or recycle of equipment, structures and material;
4.2 Release of the entire site for authorized use (depending on future plans) at the
end of closure.
5.91 Each of these sets of criteria should be established on the basis of realistic
exposure scenarios.
5.925.89 Guidance on removal from regulatory control and on cleanup levels can
be found in [19] & [20].
INSTITUTIONAL CONTROL
5.935.90 Institutional control comprises those actions, mechanisms and
arrangements implemented so as to maintain control or knowledge of a waste
management site after closure, as required by the regulatory body. This control may be
active (for example, by means of monitoring, surveillance, remedial work, and fences)
or passive (for example, by means of land use controls, markers, records, etc.). The
need for, and dependence on, active institutional controls should be minimized in the
design.
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5.945.91 It is anticipated that only a few NORM waste management facilities
will require active institutional controls to be applied in the long-term. Examples
include facilities containing uranium mill tailings and low-volume, high-activity scales
and sludges. In contrast, passive controls may be required for a minority of NORM
waste disposal sites.
5.955.92 The operator is responsible for preparing the programme for
institutional control, which should be reviewed and approved by the regulatory body.
The design of the programme should be based on a safety assessment, in which
impacts on human health and the environment over an appropriate period into the
future are considered.
5.965.93 The operator should determine the period over which institutional
controls can be assumed to remain effective and this determination should be
approved by the regulatory body. Scenarios postulating human intrusion, failure of
engineered structures and developments in the environment should be considered in
the safety assessment.
5.975.94 Establishment of the requirements for institutional control should be a
part of the optimization of the design for closure. The need for, and dependence on,
active institutional controls should be minimized in the design.
5.985.95 As part of an institutional control programme, all relevant records of
the location and characteristics of closed waste management facilities, restrictions on
land use and ongoing monitoring and/or surveillance requirements should be
maintained in accordance with applicable legal requirements. Legal provision should
be made for the regulatory body to withdraw or modify components of the
institutional control programme, as deemed appropriate in the light of results of
monitoring and surveillance. Information on the site, the required institutional controls
and the rationale or need for such controls should be documented and made publicly
available.
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6. SAFETY ASSESSMENT AND SAFETY CASE
INTRODUCTION
6.1 This section describes the approach to conducting safety assessments for
management of radioactive residues generated from NORM related facilities and
activities. The safety assessment should indicate how the residue management
facilities should be designed to provide optimum protection to workers, the public and
the environment.
The key points established in this section are as follows:
The safety assessment should take place at the design stage of facility
development and should cover the operational, closure and post-closure phases
of the facility
A graded approach should be taken in assessing the range of activities and
facilities related to NORM management
The safety assessments should be well documented and updated as necessary to
reflect changes in operation or regulatory requirements
GENERAL CONSIDERATIONS
6.2 Requirements for the safety assessment for all facilities and activities are set out
in Ref. [9]. Safety assessment for the management of NORM residues entails
assessing the facilities and activities that produce NORM residues, pre-disposal
management of residues, and disposal of radioactive wastes. Specific requirements
for the disposal of radioactive waste are described in Ref. [4].
6.3 The prime responsibility for safety throughout the lifetime of a facility lies with
the operating organization [3]. This includes responsibility for both assessing and
ensuring the safety of the facility throughout its lifecycle.
6.4 Safety assessment is undertaken in conjunction with the planning and design of
a proposed facility or activity. While planning a NORM residue facility and/or activity,
the operating organization should start to prepare and develop a safety case that
demonstrates the safety of the proposed facilities and/or activities and demonstrates
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that the proposed activities will be in compliance with the safety requirements and
criteria set out in national laws and regulations.
6.5 The operating organization should use the safety assessment to establish specific
operational limits, conditions and administrative controls. The operating organization
may wish to set an operational target level below the limits and controls to assist in
avoiding any breach of those that may be approved.
6.6 The results of the safety assessment should provide the primary input to the
authorizing documentation required to demonstrate compliance with regulatory
requirements with consideration of the integration of the whole of pre-disposal residue
management and disposal. An important outcome of the safety assessment is the
facilitation of communication between interested parties on issues relating to the
facility or activity. The results of the safety assessment can be used to determine any
necessary changes in the plans or design so that compliance with all requirements is
ensured. The results are also used to establish controls and limitations on the design,
construction and operation of the facility.
6.7 The various stages in the lifetime of the NORM residue facility (i.e. siting,
design, construction, operation and closure, and post closure) and activity (residue
generation, treatment, reuse/recycle, storage and disposal) should be taken into
account in the safety assessment. The safety assessment should be periodically
reviewed be revised as necessary to reflect changes in operation or regulatory
requirements.
GRADED APPROACH FOR SAFETY ASSESSMENT
6.8 A graded approach should be taken in developing safety case and conducting
safety assessments for the broad range of facilities and activities related to NORM
residue management. Three aspects [9] to be considered in a graded approach are:
Magnitude of the possible radiation risks;
The maturity of measures to manage risk;
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The complexity of the facility and/or activity.
6.9 Paragraph 3.3 of Ref [9] states ‘The main factor to be taken into consideration in
the application of a graded approach is that the safety assessment has to be consistent
with the magnitude of the possible radiation risks arising from the facility or activity’.
The safety case should be developed and assessment should be conducted only to a
level of detail that is appropriate both to the magnitude of the risks and to the stage of
development of the facility and activity. The approach should also account for any
releases of radioactive material in normal operation, the potential consequences of
anticipated operational occurrences and possible accidents, and the possibility of the
occurrence of very low probability events with potentially high consequences.
6.10 The consideration of maturity relates to the use of proven practices and
procedures, proven designs, data on operational performance of similar facilities or
activities, uncertainties in the performance of the facility or activity, and the
continuing and future availability of experienced manufacturers and constructors. In
this sense, consideration of maturity may refer to:
(i) tThe use of well-established practices, procedures and designs,;
(ii) tThe availability of knowledge of the operational performance of similar
facilities or practices (and the associated uncertainties); and,
6.10 (iii) tThe availability of experienced manufacturers, constructors and those
conducting safety assessment. In general, the necessary depth of assessment and
review efforts will be reduced with increasing levels of maturity.
6.11 Complexity relates to the extent and difficulty of the effort required to construct
a facility or to implement an activity, the number of related processes for which
control is necessary, the extent to which radioactive material has to be handled, the
longevity of the radioactive material, and the reliability and complexity of systems and
components, and their accessibility for maintenance, inspection, testing and repair.
6.12 The application of the graded approach should be reassessed as the safety
assessment progresses and a better understanding is obtained of the radiation risks
arising from the facility or activity. The scope and level of detail of the safety
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assessment are then modified as necessary and the level of resources to be applied is
adjusted accordingly.
SCOPE OF THE SAFETY ASSESSMENT
6.13 The scope and extent of the assessment should be commensurate with the site-
specific issues that should be addressed. The results of the initial safety assessment
should be factored into the selection of the site and design of the NORM management
facility. The assessment should consider the significant scenarios and pathways by
which workers, the public and the environment may be subject to radiological hazards.
The scope and depth should be sufficient to identify and evaluate relevant risk
components over the lifetime of the facility. The models or methods used should allow
the effects of the various hazards in the different management options to be compared
in a consistent manner.
6.14 A safety assessment should generally include aspects such as:
A description of the site and facility, including the maximum expected
inventory of NORM residue and its acceptance criteria, the management facility
and its characteristics, structures, systems and components, and the
characteristics of items important to the safety of facility and activity.
A description of NORM residue operations at the facility and management
options outside the facility, including inventory and characteristics of residues.
Systematic identification of hazards and scenarios associated with operational
states and accident conditions and external events, special attentions should be
paid to reuse and recycle due to long life cycle and uncertainty.
An evaluation of hazards and scenarios, including screening of their
combinations that may result in a release of radioactive material, to eliminate
those of low likelihood or low potential consequences.
Assessment of the probabilities and potential consequences of the release(s) of
radioactive material identified in the hazard evaluation by quantitative analysis
and comparison of the results of the assessment with regulatory limitations.
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Establishment of operational limits, conditions and administrative controls
based on the safety assessment. If necessary, the design of the NORM residue
should be modified and the safety assessment should be updated.
Documentation of safety analyses and the safety assessment for inclusion in the
documentation supporting the licensing of the facility.
The commissioning programme.
Organizational control of operations.
Procedures and operational manuals for activities with significant safety
implications.
A programme for periodic maintenance, inspection and testing.
Monitoring and surveillance programprogrammes.
The training programme for staff.
The emergency preparedness and response plan.
The management system.
Provisions for occupational radiation protection.
Provisions for the decommissioning and remediation, if applicable.
CONDUCTING A SAFETY ASSESSMENT
6.15 The safety assessment should be conducted iteratively step by step. In general, a
safety assessment should include context for the assessment, description of the facility
and activity, development and justification of scenario, formation and implementation
of an assessment models, performance of calculation and analysis of results, and
comparison with assessment criteria.
6.16 The context for the assessment involves the following key aspects: the purpose
of the assessment, the philosophy underlying the assessment, the regulatory
framework, the assessment endpoints, and the time frame for the assessment.
6.17 In determining the assessment time frame, account should be taken of the
characteristics of the particular facility or activity, the site and the design of the
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facility. Other factors that should be considered include natural external hazards and
social change.
6.18 Long term management facility of NORM residue, including long term storage
and disposal) may involve a period of time that exceeds the normal design lifetime of
civil structures, including short term storage facilities, and this will have implications
for the selection of construction materials, operating methods, and quality assurance
and quality control. The rationale for selection of the assessment time frame should be
explained and justified.
6.19 Storage is, by definition, an interim measure, but it can last for several decades
or even longer. The intention in storing NORM residue is that it can be retrieved for
reuse, recycle reprocessing or processing and/or disposal at a later time. In the safety
assessment, a plan for the safe handling of the NORM residue, following the period
of storage, should be considered and the potential effects of degradation of the facility
and/or any elements of the containment on the ability to retrieve and handle the
NORM residue should be assessed.
6.20 The possibility of inadvertent human intrusion should be considered relevant
when assessing the safety of a long term management facility because the facility may
require continued surveillance and maintenance not only during operation, but also
after closure. Prevention of intentional human intrusion requires adequate security
arrangements and these should be addressed in the safety assessment.
6.21 If the initial safety assessment yields results that are close to or exceed the
limiting performance objectives, it may be necessary to carry out a more rigorous
evaluation of the suitability of any generic data sources that may have been used,
and/or an inventory reduction or additional safety systems and controls may be
necessary.
6.22 With regard to quantitative regulatory criteria, Ref. [4] states that “doses or risk
to the representative person who might be exposed in the future as a result of possible
natural processes affecting the disposal facility does not exceed a dose constraint of
0.3 mSv in a year or a risk constraint of the order of 10-5
per year”.
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6.23 If several facilities exist or are planned for the same site, the impact of all
facilities should be taken into account in establishing which criteria to consider and
when comparing the results of the assessment with these criteria. This may not be
straightforward if a mixture of old and new facilities exists at a site, or if the periods
over which risks in principle could exist are different for each facility at the site. In
such situations, consultation between the operator and the regulatory body will usually
be necessary in order to specify what criteria are to be used in the assessment.
6.24 A clear description of the endpoints for the assessment should be provided,
together with a justification for their selection, including endpoints for radiological
impact such as dose or risk, other safety indicators such as concentrations and fluxes
of radionuclides, and impacts on non-human species.
6.25 For the assessment of reuse and recycle of NORM residue, the receptor should
be determined according to the life cycle of the reuse and recycle.
6.26 The safety assessment should have clear description of the facility, activity and
residue. The characteristics of the potential sites would determine the generation of
contaminants and their transport from the sites. These data should be used, as
appropriate, for the calibration and validation of models and to establish reference
levels for monitoring and surveillance activities during all phases in the lifetime of the
waste management facility.
6.27 Potential options for managing the residue should be identified according to the
considerations outlined in Section 4. A broad range of options should be considered
for the initial analysis. The behavior of the various options for managing the residue
should be modeled using appropriate models and parameter values.
6.28 The operator should determine which institutional controls may be applicable
after closure of the residue management facility and should describe their key
characteristics, including the period over which they may be assumed to remain
effective. These controls should be proposed to the regulatory body and should be
reviewed as part of the closure plan. Guidance is provided in Section 5.
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6.29 The set of safety assessment scenarios should take account of all relevant
existing and potential hazards arising for the facility or activity, and their interrelation
and evolution over the lifetime of the facility or activity according to the safety case
and the context for the assessment. The features, events and processes to be
considered in the safety analysis are to be selected on the basis As basis of the
development and justification of scenarios, of a systematic approach, and justification
has to be provided that the to identification and screening of hazards scenarios
relevant for safety is sufficiently comprehensive [9].hould be taken on the basis of the
description of facility and the activities. The following steps should be applied in an
iterative manner in order to identify scenarios for normal operation and anticipated
operational occurrences and accident conditions that could lead to the exposure of
workers and members of the public, or adversely impact the environment:
6.29
Identification of hazards and initiating events: This should consider the
inventory, activity, physical conditions and location of the waste and other
radioactive material, together with any additional hazards arising from activities
or processes for its management, and should identify where initiating events
create the potential for causing harm to human health and/or the environment;
Screening of hazards: The hazards identified should be quantified and screened
in order to direct efforts toward all significant and relevant hazards and
initiating events for the facility or activity;
Identification of scenarios: The safety analysis should identify all relevant
scenarios arising from either processes or accident situations in which the
screened hazards could be realized.
Screening Assessment Methodology
6.30 The hazards identified should be quantified and screened in order to direct
efforts towards all significant and relevant hazards for the facility or activity. Hazards
lacking the potential to cause harm to human health and/or the environment to a
degree that exceeds relevant safety requirements or criteria, or which cannot be
realized given the scope of the facility or activity being assessed, can be screened out
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from the subsequent hazard analysis. In the re-evaluation of a safety assessment, such
screening arguments should be reviewed to check that they remain valid.
6.31 Assessment scenarios for screened hazards should be generated in a systematic
manner (e.g. by the identification of postulated initiating events). Consideration
should be given to all postulated initiating events through which harm could be
realized, in particular:
External initiating events;
Internal initiating events at the facility or the site, e.g. fire, explosions, collapse
of structures, leakages or spillages, failure of ventilation, drops of heavy loads,
failure of protective measures (e.g. shielding, personal protective equipment);
and
Human induced initiating events such as operator errors and violations,
misidentifications, and the performance of incompatible activities.
Consideration should also be given to the potential for new initiating events to
be caused by actions taken during the evolution of an accident to mitigate the
consequences of the accident.
6.32 Once the scenarios have been developed, the corresponding assessments should
be carried out. This is commonly undertaken using assessment models. An assessment
model will generally be developed from the following components: a conceptual
model, a mathematical model, and a computer code. Often specific models have to be
developed for particular processes and/or system components. For the purposes of
safety assessment, these models will need to be linked in such a way that it is possible
to assess the potential radiological impacts of the facility or activity as a whole. The
model linking and the use of more detailed models to support simplifications made for
safety assessment purposes should be properly managed in accordance with relevant
quality assurance measures.
6.33 Both conservative and realistic calculations might be necessary in radiological
impact assessment for the period after closure, and both approaches can be used to
increase confidence in the safety of the disposal facility. For example, conservative
models can be used, especially in early phases of assessment, to assess quickly the
performance of part of or the entire disposal system. If the results of an initial
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screening assessment do not satisfy the screening criteria, a more realistic assessment
should be carried out followed by an even more detailed assessment if required.in an
iterative manner.
6.34 Simple conservative models may also be used to increase confidence in results
obtained with more complex models. Conservative models are also necessary to deal
with uncertainties that are not amenable to quantification. Conservative estimates may
be used in the assessment for some parameters, whilst realistic values based on
detailed characterization and/or more realistic models may be used for others.
6.35 The decision to use a conservative approach, a realistic approach, or both will
depend on a number of factors such as the nature and objective of the assessment,
regulatory requirements, the availability of data and scientific understanding, the
complexity of the site and the facility, and available resources.
6.36 The assessment cases should adequately address the appropriate scenarios using
the conceptual models and site and facility or activity design information. A sufficient
range of sensitivity and uncertainty analyses should be performed to contribute to
understanding of the system and to identify parameter correlations that have not been
treated in an appropriate way.
6.37 When presenting the output from safety assessment calculations, sufficient
results should be provided as are necessary for comparison with both the ultimate
assessment end points and any alternative or sub-system safety or performance
criteria. Guidance on the use of the safety assessment results should be provided. For
example, it should be explained whether the safety assessment results (end points) will
be compared directly with regulatory criteria (e.g. safety targets) or whether they will
be used for illustrative or other purposes.
6.38 It is not in itself sufficient that the calculated doses are less than a dose
constraint for acceptance of a safety case for a facility or activity, since protection is
also required to be optimized. If the safety assessment results do not demonstrate
compliance with safety requirements or criteria, the assessment should be revised. The
results of the revised assessment should be used to identify proposed amendments to
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the existing safety case, or to identify activities, engineering and protective safety
measures, and, where appropriate, additional safety measures to ensure compliance
with the requirements and criteria. The treatment or reduction of uncertainties in the
safety assessment should be reviewed and, where necessary, revised.
6.39 Any lessons learned in applying the models and interpreting the results should
be used to revisit assumptions and decisions made during the course of model
development. It is likely that such information can be used to refine the model,
perhaps by identifying particularly important processes or particularly sensitive
parameters.
6.40 The assessment of non-radiological impacts will be required and governed by
environmental protection legislation. This lies outside the scope of this Safety Guide.
Nevertheless, the approaches to assessment described in this Safety Guide may also be
of use in the assessment of hazards posed by non-radioactive waste and in
optimization of protection and safety against all potential hazards.
DOCUMENTATION OF SAFETY CASE AND SUPPORTING SAFETY
ASSESSMENT
6.41 The safety assessment shall be documented at a level of detail and to a quality
sufficient to demonstrate safety, to support the decision at each stage and to allow for
the independent review and approval of the safety case and safety assessment. The
documentation shall be clearly written and shall include arguments justifying the
approaches taken.
6.42 Particular consideration should be given to ensuring that the level of detail is
commensurateis commensurate with the importance to safety of the particular system
or component and its complexity, and that an independent reviewer will be able to
reach a conclusion on the adequacy of the assessment and the arguments employed,
both in their extent and in their depth. Assumptions used in the safety case must be
justified in the documentationdocumentation, as must the use of generic information.
6.43 Because of the long time frames potentially involved, a plan for adequate record
keeping over the expected time frame should be considered in the safety assessment.
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6.44 The regulatory framework governing the conduct of safety assessment should be
documented as part of the context for the assessment, and the safety assessment should
be conducted in a manner consistent with that framework. Thus, the safety criteria to
be used in the assessment typically will be specified by the regulatory framework.
PERIODIC SAFETY REVIEWS
6.45 The operator shall carry out periodic safety reviews and shall implement any
safety upgrades required by the regulatory body following this review. The results of
the periodic safety review shall be reflected in the updated version of the safety case
for the facility.
6.46 The safety assessment should be periodically reviewed in accordance with
regulatory requirements. The review of management systems should include aspects
of safety culture. In addition, the safety case and supporting safety assessment should
be reviewed and updated:
(a) When there is any significant change to the facility or to its radionuclide
inventory that may affect safety.
(b) When changes occur in the site characteristics that may impact on the
storage facility, e.g. industrial development or changes in the surrounding
population.
(c) When significant changes in knowledge and understanding occur (such as
from research data or from feedback of operating experience).
(d) When there is an emerging safety issue due to a regulatory concern or an
incident.
(e) Periodically, at predefined periods, as specified by the regulatory body.
Some States specify that a periodic safety review be carried out not less
frequently than once in ten years.
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7. MANAGEMENT SYSTEMS
7.1 This section provides a general overview of the management system
requirements with a particular emphasis on the long-term management aspects
associated with the management of NORM residues. Further direction and guidance
may be found in Reference [11] and associated guidance documents.
7.2 The requirements for establishing, implementing, assessing and continually
improving a management system to ensure the protection of people and the
environment for facilities and activities including those that generate NORM residues
are set out in Ref [11]. The requirements include:
Management responsibility including organization and planning;
Resource management including the provision of resources and training;
Process implementation including the control of work processes, documents,
records, materials and equipment: and,
Measurement and assessment including verification, self-assessment and audits.
7.3 Guidance on management systems for processing, handling, storage and
disposal of radioactive wastes including NORM residues can be found in Refs [21] &
[22].
7.4 The management system for the processing, handling, pre-disposal and disposal
of NORM residues must be developed, managed and integrated within the existing
management system that addresses all facilities and activities overseen by the
operating organization.
7.5 A management system is required to be established, implemented, assessed and
continually improved by the operating organization and it should be applied to all
stages of NORM residue management that have a bearing on health, safety or
environmental protection. It should be aligned with the goals of the operating
organization and should contribute to their achievement.
7.6 The use of a graded approach in the application of management system
requirements is particularly important in the management of NORM residues to ensure
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the degree of formalization, oversight, documentation and assessment is
commensurate with the complexity of the facility and activities and the overall risks
associated with the NORM residues to be managed.
MANAGEMENT RESPONSIBILITY
7.7 NORM residue management facilities, like any facility for the management of
long lived radioactive wastes, must be able to perform over very long periods of time.
As a result, the management system must be sufficiently robust but flexible so that it
can evolve over the life of the facility. Since the responsibility for the management of
NORM residues is expected to change during the life of the storage or disposal facility
from the generator, to possibly a third party oversight organization and finally
government, the management system and in particular the records management system
must take into account and facilitate the transfer of responsibility across these various
entities.
7.8 While early planning and effective controls are important elements of any
management system, this is particularly important in the management of NORM
residues. Several member states have faced extensive costs and significant technical
challenges to address legacy issues surrounding the long-term management of large
volumes of NORM residues. Proper planning in the generation, characterization,
processing, pre-disposal and disposal of NORM residues is essential to ensure long
term performance and minimize long term costs,
7.9 The long term nature of NORM residue management means that particular
consideration should be given to establishing and maintaining confidence that the
performance of the facilities and activities will meet the health, safety and
environmental protection requirements over the lifetime of the facility to the end of its
decommissioning and into institutional control. This includes the creation of the
funding arrangements that will be necessary to manage the facilities in the long term.
7.10 National and international policies and principles for NORM residue
management that currently constitute an accepted management arrangement can
evolve over the lifetime of the facility. Policy decisions, technological innovations and
advances or plans for re-processing of residues to further extract resources can lead to
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fundamental changes in the management strategy for NORM residues. However, the
operating organization retains its responsibility for all activities at all times and
continuous commitment by the organization remains a prerequisite to ensuring safety
and the protection of human health and the environment.
7.10
RESOURCE MANAGEMENT
7.11 NORM residue management activities will require financial and human
resources and the necessary infrastructure at the site where the facility is located.
Senior management should be responsible for making arrangements to provide
adequate resources to satisfy the demands imposed by the safety, health,
environmental, security, quality and economic aspects of the full range of activities
involved in the management of NORM residues and the potentially long duration of
such activities.
7.12 For the plans, goals and objectives that define the strategy for achieving an
integrated approach to safety, interactions with all interested parties should be
considered, as well as long term aspects such as:
(a) Provision of adequate resources (the adequacy of resources for maintenance
of facilities and equipment may need to be periodically reviewed over
operational periods that may extend over decades);
(b) Preservation of technology and knowledge and transfer of such knowledge
to people joining the programme or the organization in the future;
(c) Retention or transfer of ownership of NORM residue management facilities;
(d) Succession planning for the technical and managerial human resources;
7.12 (e) Continuation of arrangements for interacting with interested parties.
7.13 Arrangements for funding of future NORM residue management activities
including the funding of future institutional control should be specified and
responsibilities, mechanisms and schedules for providing the funds should be
established in due time. The generator of the NORM residues should be accountable
for providing appropriate funding.
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7.14 Management systems for NORM residue management activities should include
provision to deal with several funding challenges. This is discussed in further detail in
Section 9.
7.15 For long-term management activities, future infrastructural requirements should
be specified and plans should be made to ensure that these will be met. In such
planning, consideration should be given to the continuing need for support services,
spare parts for equipment that may eventually no longer be manufactured and
equipment upgrades to meet new regulations and operational improvements, and to the
evolution and inevitable obsolescence of records and document management software
and databases.
7.16 Everyone involved in the design, construction, commissioning, operation and
closure of NORM residue management facilities and whose performance could
influence safety should be trained to an appropriate and verified level. Accumulated
experience, including lessons learned from incidents and events, should be reviewed
periodically and should be used in revising training programprogrammes and in future
decision making.
PROCESS IMPLEMENTATION
7.17 The management system should ensure that there are adequate processes
including documented procedures and work instructions for siting, design,
commissioning, operation, maintenance, decommissioning closure and institutional
control. The management system should be designed to ensure that safety and
protection of human health and the environment is maintained, and that the quality of
the records and of subsidiary information on the inventories of NORM residues is
preserved, with account taken of the duration of any proposed storage period and the
consecutive management steps, for example, reprocessing or disposal. The
management system should also include provision to ensure that the fulfillment of its
goals can be demonstrated.
7.18 Models and codes used in the safety assessment should be validated and verified
to the extent possible. A feedback process should be established and the results of the
safety assessments should be taken into account appropriately during the design.
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7.19 All relevant records of the location and characteristics of closed NORM residue
management facilities, restrictions on land use and on-going maintenance and/or
surveillance requirements should be maintained in accordance with applicable legal
requirements. Legal provision should be made for the regulatory body to withdraw or
modify components of the institutional control programme, as deemed appropriate in
the light of results of monitoring and surveillance. Information on the site, the required
institutional controls and the rationale or need for such controls should be documented
and made publicly available.
7.20 Records concerning NORM residue management that need to be retained for an
extended period should be stored in a manner that minimizes the likelihood and
consequences of loss, damage or deterioration due to unpredictable events such as fire,
flooding or other natural or human initiated occurrences. Storage arrangements for
records should meet the requirements prescribed by the national authorities or the
regulatory body and the status of the records should be periodically assessed. If
records are inadvertently destroyed, the status of surviving records should be
examined and the importance of their retention and their necessary retention periods
should be re-evaluated.
MEASUREMENT, ASSESSMENT AND IMPROVEMENT
7.21 The effectiveness of the protection achieved in the management of NORM
residues should be assessed periodically. This includes re-assessing the overall
effectiveness of the management system to ensure that continues to meet the
organizational needs and regulatory expectations that are expected to evolve over
time.
7.22 Independent verification including inspections and audits of the design,
construction and the operation of the residue management facilities should be
undertaken in order to ensure that they are designed, constructed and operated as
intended, and that deficiencies are corrected. In so doing, it is essential that these
verifications are conducted prior to the initiation of any activities for which
implementation of any corrective measures would prove to be very difficult (e.g.
verification of liner construction prior to waste placement).
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7.23 Facilities for the long termlong-term management of NORM residues often
involve engineered structures that require routine and long-term inspection and
verification. Measures should be put in place to facilitate third party independent
verification including geotechnical inspections to ensure the engineered structures
such as berms and dams are performing as intended. This should form part of the
monitoring and surveillance programprogramme, which is further discussed in the
next chapter.
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8. MONITORING AND SURVEILLANCE OVERVIEW OF
MONITORING AND SURVEILLANCE
o
o This chapterSection outlines reminds the definition of the the objectives and
design of the monitoring monitoring and surveillance, and describes the
responsibilities of the operator and regulatory body and the objectives and design of
the monitoring.
o8.1 . The Kkey points are theas followings:
1) A graded approach is recommended to adapt the level of detail (duration
frequency, locations for sampling, parameters..) for monitoring and surveillance
programprogrammes with the level of the potential hazards associated with the
facility;
2) The monitoring and surveillance programprogramme should be reviewed
periodically by the operator and the regulatory body and also following any
major changes in waste management operations (including the period of lifetime
of the site);
3) It is necessary to establish the baseline conditions for comparison with later
monitoring results because radionuclides present in NORM residue are already
present in nature;
4) Consideration should be given to ensure transparency (communication to the
public).
OVERVIEW OF MONITORING AND SURVEILLANCE
8.2 Monitoring has been defined in various publications of the IAEA in different
ways [GSR-3], [RS-G-1.8], . Draft safety guide DS357 states that the term monitoring
refers to: consists of “Ccontinuous or periodic observations and measurements to help
evaluate the behaviourbehavior of the components of a waste disposal system, and the
impact of the waste disposal system on the public and the environment. More
specifically, it covers the measurement of radiological, environmental and engineering
parameters. “
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o
8.3 The duration and frequency of monitoring should be in accordance with the
time-scale of natural variations in the processes and in the parameters being measured,
as determined by regulatory requirements, and with changes in processes and
parameters associated with construction and operation of the disposal facility.
o
o In the draft safety guide DS357 the term surveillance refers to: “The physical
inspection of a waste disposal facility in order to verify the integrity of the safety
barrier”.
8.4 Surveillance is employed periodically to verify through inspection that
structures, systems and components continue to function as described in the safety
case. In this respect the function of surveillance is to facilitate the detection of changes
in the engineering structures and systems of the disposal facility that might affect the
performance of the disposal system. and integrity of the safety barriers.
o
8.5 The level of detail for monitoring and surveillance programprogrammes should
be consistent with the level of the potential hazards associated with the facility and a .
A graded approach is recommended., as in many cases
o
o8.6 The monitoring and surveillance programprogramme should be reviewed
periodically and also following any major changes in waste management operations
(including the period of lifetime of the site) or in regulatory requirements.
RESPONSIBILITIES OF THE OPERATOR AND REGULATORY BODY
o8.7 The operator of the waste disposal facility should be responsible for carrying
out the activities relating to monitoring and surveillance (design including record
keeping and archiving) that meets the requirements established by the regulatory body
for each period of the lifetime of the site and should: :
Records of the results of the programme should be maintained in a form readily
amenable to interrogation [23];.
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Prior to termination of the operator’s responsibility the operator should provide
the regulatory body with the results of a final radiological and environmental
survey and a closure completion report in order to document compliance with
the regulatory requirements for managing the waste..
o8.8 The regulatory body should:
pPeriodically review the regulations in force for monitoring and surveillance,
the monitoring and surveillance programmes and reporting arrangements;
rReview the monitoring and surveillance data provided by the operator against
established requirements;
vVerify that waste disposal facility is being appropriately monitored and
controlled by the operator; this may include the independent conduct of
monitoring and surveillance.
OBJECTIVES AND DESIGN OF THE MONITORING
8.9 Monitoring and surveillance activities must be adapted to each period in the
lifetime of a radioactive waste disposal facility : pre-operationnaloperational period,
operational period (including closure operation) and post closure period. Those
differents periods and correspondingand corresponding objectives can be further
described as follows:
o
o8.10 The pre-operational period includes concept definition, site evaluation
(selection, verification and confirmation), and safety assessment and design studies.
tThe objectives are the following:
• To contribute to the evaluation of suitability of the site;
• To provide input data for the design of the facility;
• To provide input data necessary for the operational and post-closure safety
cases;
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• To establish baseline conditions for comparison with later monitoring results;
This is especially important in respect of NORM residues, where the same
radionuclides are already present in nature
• To aid in designing the monitoring programme for the operational period.
o8.11 The operational period begins when waste is first received at the facility. From
this time, radiation exposures may occur as a result of waste management activities.
This period includes operations necessary to close the disposal site (such as
decommissioning, sealing, remediation, etc). The objectives of the monitoring
programme during the operational period are the following:
To provide data on the as-built properties of materials and structures, for
confirmation of the performance of elements of the disposal system, which may
be used to revise, improve or build confidence in the post-closure safety case;
To provide information necessary for checking whether systems for effluent
treatment and control are performing properly;
To provide early warning of any deviations from normal operation;
To provide data on the discharge of radionuclides to the environment, for use in
predictive modelling for estimating radiation levels and activity concentrations
in the environment and exposure of the public (e.g. rates of discharge and
radionuclide compositions).
o8.12 The post-closure period begins at the time when all the engineered
containment and isolation features have been put in place, operational buildings and
supporting services have been decommissioned, and the facility is in its final
configuration. Objectives of the monitoring programme for the period after closure are
to demonstrate that the facilities are performing as predicted in the design and include
the following.
To detect abnormal radiological concentration or activity in the environment
that could be attributable to the disposal facility;.
To verify the performance and integrity of barriers;
To validate the achievement of post-closure radiation exposure objectives;
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To inform the decision to move from a period of active institutional control to a
period of passive institutional control (established by means of, for example,
site markers and maintenance of ‘corporate memory’);,
To determine need for, and type of, monitoring and surveillance activities to be
conducted during the institutional control period.
o8.13 The monitoring and surveillance programme should specify the parameters to
be monitored, the locations and frequencies for sampling, and the procedures for
analysis and reporting including the setting of appropriate action levels. Such a
programme should include measurement of:
Indicators of environmental impacts, such as levels of radionuclides and non-
radiological contaminants in air, water and soil;
The physical integrity of structures and systems for waste containment;
Parameters that may assist in the interpretation of data, such as meteorological
data, operational process data and waste stream data.
o8.14 In order to ensure transparency, in the design of the monitoring programmme
consideration should be given to how the results are to be communicated to the public.
Transparency includes the responsibility to provide a clear interpretation of results and
the context for the measurements.
o8.15 The need to address public concern and expectations may also be considered in
defining the monitoring programme.
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9. FINANCIAL ASSURANCE
9.1 This Section outlines the financial assurance requirements necessary to
confirm that adequate funding is available at the time of decommissioning and
closure. The timing of establishing funding is critical, starting at the planning stage of
a project, and that periodic adjustments are made so that funding is in place before it
is needed.
9.2 Adequate legal requirements are needed so that accesses to the funds are
assured at the time of a potential default and that the funds are isolated for the for the
purpose of decommissioning of the project. Key points are the followings:
5) A financial surety mechanism to be used in the event of business insolvency is
crucial to assuring that management and decommissioning of residues occurs;
6) Consideration of the financial surety should begin in the planning stage of a
project and be periodically revised as estimates change;
7) Legal requirements are needed to assure that the funding can be accessed at the
time it is needed and that the funding is separated from other uses;
8) A graded approach should be used to ensure that the requirement for provision
of funds for the management of NORM residues be proportional to the
radiological risks involved.
9.3 Governments are required to establish a national policy and strategy for safety
which must include the provision of appropriate financial resources for
decommissioning of facilities and management of radioactive waste, including its
storage and disposal [3].
9.4 To avoid any undue burden on future generation, it is important that there be
sufficient funds set aside so that the financial resources are available for
decommissioning, remediation, radioactive waste disposal, and post closure
management. A liability on future generations would exist if these funds were absent
or insufficient.
9.5 There is an identified need for legal requirements to assure funding provision
and adequacy. Legal requirements are also necessary to protect against such factors as
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misuse of funds, claims on funds during potential financial crisis or, business
insolvency, such a bankruptcy or cessation of business. Mechanisms should be in
place to assure funds are structured and managed to keep pace with factors such as
inflation, changes in operational scale or technology, and to ensure transparency of
the process which must withstand the scrutiny of the operator/licensee, the regulator
and the public [21].
9.6 In keeping with a graded approach to the management of radioactive residues,
the regulator should ensure that the requirement for provision of funds for the
management of NORM residues be proportional to the radiological risks involved.
9.7 Funding arrangements for managing NORM residue disposal activities should
be specified, and responsibilities, mechanisms and schedules for providing funds
should be established before the funds are needed. In particular, the funds that will be
necessary should be ensured before termination of the practice that generates the
residue. In general, it is expected that the operator would fund the management of the
NORM residue, in keeping with the ‘polluter pays’ principle.
9.8 The regulator should ensure consideration is given to the provision of
adequate funding at the planning stage [21]. It should be recognized that it may be
difficult to make a realistic estimate of costs for residue management activities that
are still in the planning stage, especially where there may be considerable uncertainty.
Cost estimates for long-term management of residues should therefore be updated
periodically as planning certainty improves. The cost estimate for decommissioning
liabilities should be carried on the operator’s financial statements.
9.9 Regulatory requirements for the provision of financial assurance for NORM
residue management activities should consider several potential funding challenges:
1. Business insolvency: For various reasons (e.g. bankruptcy, cessation of
business), it may not be feasible to obtain the necessary funds at the time of
closure, especially if funds were not set aside at the time the benefits were
received from the activity.
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2. Transfer of ownership: Ownership of the NORM residues may be transferred
between parties; provisions for financial assurance must also be transferred.
3. Dedicated funding: If funds are to come from public sources, this will compete
with other demands for public funding and it may be difficult to gain access to
adequate funds on a timely basis.
4. Estimation uncertainty: It may be difficult to make realistic estimates of costs
that are still in the planning stage and for which no experience has been
accumulated.
5. Changing Expectations: It may be difficult to determine appropriate risk and
contingency factors to be built into estimates of future costs, owing to the
uncertainties associated with future changes in societal demands, changes to
standards, political imperatives, public opinion and the nature of unplanned
events that may require resources for dealing with them.
Longevity: It may be problematic to establish an adequate degree of confidence
in all the arrangements so that the necessary continuity of funding throughout
the entire series of activities is ensured.
6.
9.10 For these reasons, it is recommended that the regulator establish a suitable
process for estimating the cost of rehabilitation of a NORM residue generating
storage or disposal activity at any stage of the activity, and ensure adequate funding is
available at that stage and for each waste stream..
9.11 In addition, the planning for the NORM residue generating operation should
incorporate plans for managing decommissioning of facilities, remediation,
radioactive waste disposal, and post termination management of the facilities from the
beginning of the project, to ensure a safe, secure and stable end point that meets
licensing requirements.
9.12 It is not possible to establish a specific methodology for assuring funding
adequacy for all countries. However, the process typically will involve periodic
government or operator review and updating of derived estimates of costs.
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9.13 Based on the periodically updated cost estimate, the calculated sum may be
accumulated, or made available when required through the use of various financial
vehicles. These may include invested funds accumulated year-by-year over the
lifetime of the NORM generating activities, through the use of a standby trust, bonds,
irrevocable letters of credit, insurance, or expressed commitments from a government.
In some countries it is typical to use a contingency factor in the surety to deal with
cost uncertainty (e.g. 15-20%).
9.14 The method for making the funds available at the time of decommissioning
and rehabilitation will vary across Member States. Typically these will involve
spending limits relative to specific milestones.
9.14
9.15 The operator’s management system should include a documented set of
policies that establish the management’s plans objectives and priorities with regard to
safety, health, environmental, security, quality and economic considerations [24].
Those policies outline senior management’s commitments to attaining their goals and
objectives, and their priorities and means for continual improvement. This system
should include management commitments to estimating and providing the adequate
financial resources required by the regulator for NORM management.
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REFERENCES
[1] INTERNATIONAL ATOMIC ENERGY AGENCY, IAEA Safety Glossary, Terminology
used in Nuclear Safety and Radiation Protection, 2007 Edition, IAEA Vienna
[2] INTERNATIONAL ATOMIC ENERGY AGENCY, Fundamental Safety Principles,
Safety Fundamentals, Safety Standards Series No. SF-1, IAEA, Vienna (2006).
[3] INTERNATIONAL ATOMIC ENERGY AGENCY, Governmental, Legal and Regulatory
Framework for Safety, IAEA Safety Standards Series No. GSR Part 1, IAEA, Vienna
(2010).
[4] INTERNATIONAL ATOMIC ENERGY AGENCY, Disposal of Radioactive Wastes,
IAEA Specific Safety Requirements No. SSR-5, IAEA, Vienna (2011).
[5] INTERNATIONAL ATOMIC ENERGY AGENCY, Application of the Concepts of
Exclusion, Exemption and Clearance, IAEA Safety Standards Series No RS-G-1.7, IAEA,
Vienna (2004).
[6] INTERNATIONAL ATOMIC ENERGY AGENCY, Occupational Radiation Protection in
the Mining and Processing of Raw Materials, IAEA Safety Standards Series No RS-G-1.6,
IAEA, Vienna (2004).
[7] INTERNATIONAL ATOMIC ENERGY AGENCY, Regulatory Control of Radioactive
Discharges to the Environment, IAEA Safety Standards Series No.WS-G-2.3, IAEA,
Vienna (2000)
[8] INTERNATIONAL ATOMIC ENERGY AGENCY, Management of Radioactive Waste
from the Mining and Milling of Ores, IAEA Safety Standards Series No WS-G-1.2, IAEA,
Vienna (2002).
[9] INTERNATIONAL ATOMIC ENERGY AGENCY, Safety Assessment for Facilities and
Activities, IAEA Safety Standards Series No. GSR Part 4, IAEA, Vienna (2009)
[10] INTERNATIONAL ATOMIC ENERGY AGENCY, Predisposal Management of
Radioactive Waste, General Safety Requirements GSR Part 5, IAEA Vienna (2009)
[11] INTERNATIONAL ATOMIC ENERGY AGENCY, Radiation Protection and Safety of
Radioactive Sources, General Safety Requirements, Interim Edition, GSR Part 3, IAEA
Vienna (2011).
[12] INTERNATIONAL ATOMIC ENERGY AGENCY, Regulations for the Safe Transport of
Radioactive Material, 2012 Edition, IAEA Specific Safety Requirements No. SSR-6,
IAEA, Vienna (2012).
[13] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, Scope of
Radiological Protection Control Measures, Publication 104, Elsevier Science, Oxford
(2007)
[14] INTERNATIONAL ATOMIC ENERGY AGENCY, Site Evaluations for Nuclear
Installations, IAEA Safety Standards Series NS-R-3, IAEA, Vienna (2003)
[15] INTERNATIONAL ATOMIC ENERGY AGENCY, Seismic Hazards in Site Evaluation
for Nuclear Installations, IAEA Safety Standards Series, SSG-9, IAEA, Vienna (2010)
Pag e o f 1 25 111
[16] INTERNATIONAL ATOMIC ENERGY AGENCY, Meteorological and Hydrological
Hazards in Site Evaluation for Nuclear Installations, IAEA Safety Standards Series, SSG-
18, IAEA, Vienna (2011)
[17] INTERNATIONAL ATOMIC ENERGY AGENCY, Classification of Radioactive Waste,
IAEA Safety Standards Series No. GSG-1, IAEA, Vienna (2009).
[18] INTERNATIONAL ATOMIC ENERGY AGENCY, Borehole Disposal Facilities for
Radioactive Waste, IAEA Safety Standards Series No. SSG-1, IAEA, Vienna (2009).
[19] INTERNATIONAL ATOMIC ENERGY AGENCY, Release of Sites from Regulatory
Control on Termination of Practices, IAEA Safety Standards Series No WS-G-5.1, IAEA,
Vienna (2006).
[20] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, Protection of
the Public in Situations of Prolonged Radiation Exposure, ICRP Publication 82, Elsevier
Science Ltd, Oxford (2000).
[21] INTERNATIONAL ATOMIC ENERGY AGENCY, The Management System for the
Processing, Handling and Storage of Radioactive Waste, IAEA Safety Standards Series No
GS-G-3.3, IAEA, Vienna (2008).
[22] INTERNATIONAL ATOMIC ENERGY AGENCY, The Management System for the
Disposal of Radioactive Waste, IAEA Safety Standards Series No GS-G-3.4, IAEA,
Vienna (2008).
[23] INTERNATIONAL ATOMIC ENERGY AGENCY, The Safety Case and Safety
Assessment for the Disposal of Radioactive Waste, IAEA Safety Standards Series, SSG-23,
IAEA, Vienna (2012)
[24] INTERNATIONAL ATOMIC ENERGY AGENCY, Application of the Management
System for Facilities and Activities, IAEA Safety Standards Series, GS-G-3.1, IAEA,
Vienna (2006)
Pag e o f 1 25 112
ANNEX I. ORIGIN AND CATEGORIZATION OF NORM RESIDUES
4.1 This Annex indicates a range of industry sectors where the management of
NORM residues may need consideration. A regulatory body would start
consideration by identifying which relevant industry sectors are operating in its
jurisdiction, or by receiving a notification from an industry that it is dealing with
NORM residues in its operations.
A1.1 This Annex indicates a range of industry sectors where the management of
NORM residues may need consideration. A regulatory body would start consideration
by identifying which relevant industry sectors are operating in its jurisdiction, or by
receiving a notification from an industry that it is dealing with NORM residues in its
operations.
A1.1 Having identified relevant industry sectors, priority should be given to the
the types of operation known from experience and current knowledge to be most
likely to require regulatory measures. The IAEA has identified those types of
operation likely to require regulatory control on the basis of worker doses. Table 3
below, has been adapted from Table 3 of Safety Report Series 49 [25].
Table 3: Industry sectors identified as being likely to require regulatory control
Type of
operation
Material involved
Description
Radionuclide(s)
with highest activity
concentration
Typical activity
concentration (Bq g-1
)
Mining and
milling of
uranium ores
Ore
Tailings
Waste Rock
Process water
Sludges
238U Series 12 – 2,500
1.2 - 250
X
X
X
Rare earth
extraction from
monazite
Monazite
Thorium
concentrate
Scale
Residue
232Th series 232
Th
228Ra 228Ra
40-600
Up to 800
1000
20-3000
Production of
thorium
compounds
Thorium
concentrate
Thorium
compounds
232Th
232Th
Up to 800
Up to 2000
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Comment [AJ5]: 0.1% - 20%
Comment [AJ6]: assume 90% U removal from ore
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A1.2 Ref [25] notes that “…the list is not exhaustive, but probably captures most of
the relevant types of operation. It shows that there are relatively few types of
operation that are likely to need formal regulation.”
A1.3 The above table does not refer to contaminated plant and equipment generated
during the operation or decommissioning of many of the above industrial process
facilities. Recycling of these and other materials identified in Table A1 is discussed in
Annex 2.
Manufacture of
thorium
containing
products
Thorium
compounds
Products
232Th
232
Th
Up to 2000
Up to 1000
Processing of
niobium/tantalum
ore
Ore
Pyrochlore
concentrate
Residue
Slag
232Th series 232
Th
228
Ra 232
Th
1-8
80
200-500
20-120
Some
underground
mines and similar
workplaces
Ore
Scales from Ra
rich water
226Ra, 228Ra
Up to 10
Up to 200
Oil and gas
production
Scales during
removal from
pipes/vessels
226Ra 0.1-15000
TiO2 pigment
production
Scales during
removal from
pipes/vessels
228Ra, 226Ra <1-1600
Thermal
phosphorus
production
Fume and
precipitator dust
210Pb Up to 1000
Fused zirconia
production
Fume and
precipitator dust
210Pb, 210Po Up to 600
Combustion of
Coal
Fly ash
Bottom ash
Scale
238-U, 232-Th, 40-K
210-Pb, 210-Po
238U Series
226-Ra, 228-Ra,
210-Pb
0.07 – 0.36
0.06 – 0.3
0.93 – 1.7
0.2
Up to 200
Water Treatment
Sludges 226-Ra 0.1 – 14.0 Formatted: Highlight
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Comment [AJ7]: Are the units pCi/g or Bq/g?
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Comment [AJ8]: From UNSCEAR 2000
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A1.4 Consideration can also be given to other materials associated with the industry
sectors listed in Section ZZZ4 of this Safety Guide. Table 7 Table 4 below, based on
Table 1 of Ref [25], is a useful starting point.
Table 4: Residue categories to be assessed for possible regulatory control
Category Material/operation
Radionuclide(s)
with highest
activity
concentration
Typical activity
concentration
(Bq g-1
)
Residues Red mud (alumina production)
Phosphogypsum (H2SO4 process)
238U,
232Th
226Ra
0.1—3
0.015—3
Slags Niobium extraction
Tin smelting
Copper smelting
Thermal phosphorus production
232Th
232Th
226Ra
238U
20—120
0.07—15
0.4—2
0.3—2
Scales,
sludges and
sediments
Scale (oil and gas production)
Scale (phosphoric acid production)
Residue (rare earth extraction)
Scale (TiO2 pigment production)
Scale (rare earth extraction)
Sludge (oil and gas production)
Residue (niobium extraction)
Scale (coal mines with Ra rich
inflow water)
Scale (iron smelting)
Scale (coal combustion)
Sludge (iron smelting)
Residue (TiO2 pigment production)
Sludge (water treatment)
226Ra 226
Ra 228
Ra 228Ra, 226Ra 226
Ra, 228
Th 226Ra 228
Ra 226
Ra, 228
Ra
210
Pb, 210
Po 210Pb 210
Pb 232
Th, 228
Ra 226Ra
0.1—15000
0.003—4000
20—3000
<1—1600
1000
0.05—800
200—500
Up to 200
Up to 200
>100
12—100
<1—20
0.1—14
Precipitator
dust
Thermal phosphorus production
Fused zirconia production
Niobium extraction
Metal smelting
210Pb 210Po
210Pb, 210Po 210
Pb, 210
Po
1000
600
100—500
Up to 200
a Although this material has an activity concentration of less than 1 Bq g-1, it is included because it is a building material.
A1.5 Measurement of the activity concentration levels in these materials may
indicate further residue categories where regulatory oversight may be required.
A1.6 The Regulatory Authority should decide, in accordance with the graded
approach to regulation, whether the operations can be exempted, or whether they
should be subject to authorization. A graded approach means that, where the
regulatory authority has determined that regulatory controls are necessary, the
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regulatory measures should be commensurate with the level of risk associated with the
material/operation.
REFERENCES – ANNEX I
[25] INTERNATIONAL ATOMIC ENERGY AGENCY, Assessing the need for Radiation
Protection Measures in Work Involving Minerals and Raw Materials, IAEA Safety Report
Series, No 49, IAEA, Vienna (2006).
ANNEX II. REUSE AND RECYCLING OF NORM RESIDUES
A2.1 Reuse can be defined as the reutilization for materials for the original purpose
in their original form or in a recovered state. Recycling is the utilization of valuable
materials, tools and equipment for other than the original purposes, with or without
treatment. The reuse and recycle options is attractive because there is strong economic
incentive to use the large volume of residues, to avoid the costs associated with long
term storage or disposal. The decision of whether or not to reuse and recycle residues
depends on many factors that are specific to a given stream of residue or industry or
country. Implementation of reuse and recycling options requires the availability of
suitable criteria, a suitable measurement methodology and suitable instrumentation.
Some examples of reuse and recycling of NORM residues are given in the next
paragraphs.
Scrap metal
A2.2 Scrap metals from NORM industries that are contaminated, can in many cases
be decontaminated by various methods. Details of decontamination methods as well as
measurements principles and instrumentation for equipment in the oil and gas industry
are given in Safety Report 34 [26]. The decontaminated metals can be recycled, while
the rest of the material resulting from the decontamination process, which has
generally a small volume, may be treated as NORM waste. The contaminated scrap
may also be re-melted in specific ovens to decontaminate. The natural radionuclides
often go to the slag. The metals will be clean and can be reused. Depending on the
activity concentration, the slag may also be reused, as shown in the next paragraph.
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A2.3 Smelting of contaminated scrap should be a regulated practice, and comply
with requirements set by the regulatory body. Transport of contaminated items should
comply with the requirements of the transport regulations.
Slag
A2.4 Slag from NORM industries can be used as landfill or in road construction. An
example of the latter is the use of slag from the thermal phosphorus production
industry in road construction in Florida, USA and in the Netherlands [27].
Fly ash
A2.5 Fly ash from coal-fired stations is recycled in many cases in building materials,
for instance, as additives to concrete or in lightweight building materials. While use of
fly ash in concrete blocks for building construction may not be of concern in some
Member States, others regulate the resulting levels of permissible radiation in the
concrete blocks and importation of cement with activities exceeding certain radiation
limits.
Phosphogypsum
A2.6 There are several options for recycling of phosphogypsum, such as in
agriculture as a soil amendment, in road construction and as a building material.
Detailed information can be found in [27]
Recycling in agriculture
A2.7 Soils may either be saline, having a high content of soluble salts, or they may
be alkali in which case their cation exchange sites are largely occupied by sodium
ions. Alkaline soils generally are characterized by poor drainage, which is often
caused by a dispersal of colloidal clay particles resulting in surface crusts and blocked
Pag e o f 1 25 117
soil pores. The treatment of either saline, alkali or saline-alkali soils to improve
drainage is called reclamation. Leaching can usually reclaim saline soils. But
treatment of soils with an amendment prior to leaching is recommended for alkali or
saline alkali soils. The amendment most often employed is natural gypsum, but
phosphogypsum may be used as well.
A2.8 There are, however, not only radiological issues in the recycling of
phosphogypsum in agriculture. Also other contaminants, like cadmium or fluorine
may have an impact on the applicability of recycling of this residue in agriculture.
Recycling in road construction
A2.9 Phosphogypsum when subjected to compaction can be transformed into a solid
of valuable strength. Therefore, it can be used very effectively as a binder to stabilize
on-site soil and to replace shell and clay in secondary road and parking lot
construction. Test results from an experimental road in Florida, US, indicate that there
was no leaching occurring into the groundwater and drinking water samples.
Economic analysis on the construction of the experimental roads indicated tremendous
saving on the construction cost of utilizing phosphogypsum as compared to the
traditional method of construction. Radiation monitoring during the construction of
the roads, indicated no health hazards, either to the construction crews or the residents
living in the areas.
Recycling in construction materials
A2.10 There is quite some dispute about the applicability of phosphogypsum in
building materials. Some countries use activity concentration limits that prohibit in
practice the recycling of phosphogypsum in building materials. In other countries the
requirements are more relaxed.
REFERENCES ANNEX II
[26] INTERNATIONAL ATOMIC ENERGY AGENCY, Radiation Protection and the
Management of Radioactive Waste in the Oil and Gas Industry, IAEA Safety Report Series,
No 34, IAEA, Vienna (2003SRS)
Pag e o f 1 25 118
[27] INTERNATIONAL ATOMIC ENERGY AGENCY, Radiation Protection and
Management of NORM Residues in the Phosphate Industry, IAEA Safety Report Series,
No 78, IAEA, Vienna (2013)
Pag e o f 1 25 119
ANNEX III. PRACTICAL TECHNIQUES FOR DETERMINING
RADIONUCLIDE ACTIVITY CONCENTRATIONS
INTRODUCTION
A3.1 The investigation of a legacy site or industrial activities to determine the need
for, and extent of, regulatory control of exposure to natural sources of radioactive
material is likely to involve the sampling and analysis of various solid materials to
determine the activity concentrations of 238
U and 232
Th series radionuclides. These
more detailed investigations typically follow an initial screening assessment designed
to eliminate a site whichthat poses a low level hazard from further regulatory
consideration.
A3.2 The activity concentrations need to be compared with the activity
concentration value of 1 Bq/g, below which it is usually unnecessary to regulate. The
materials requiring sampling and analysis could be encountered in large quantities
with moderate or low activity concentrations (e.g. ore, tailings, slag) or in smaller
quantities with the possibility of high activity concentrations (e.g. mineral
concentrates, scale, sludge, precipitator dust. Accordingly, the sampling method and
analysis sensitivity requirements may vary depending on the assessment to be made.
A3.2 The most probable radionuclides of interest for which activity concentrations
need to be determined are:
• Uranium series: 238
U, 226
Ra, 210
Pb and 210
Po;
• Thorium series: 232
Th, 228
Ra and 228
Th.
•
SAMPLING OF MATERIAL
A3.3 The activity concentration values mentioned above refer to the average activity
concentration in the material concerned. The amount of material giving rise to
exposure at any one time could be large, and such material could therefore exhibit a
significant range of activity concentrations. The activity concentration may also vary
over the time periods normally of concern in occupational radiation protection (e.g.
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one year). To the extent practicable, both of these variations are taken into account
when developing a suitable materials sampling strategy.
A3.4 The number of samples collected for analysis is important for obtaining a
reasonable estimate of the average activity concentration — the greater the number of
samples collected and analyzed, the greater the confidence in the figures that are
reported. There is a point, however, where any further gain in accuracy and power to
detect trends is no longer worth the time and resources needed to produce the data.
The accuracy is also affected by other factors such as the degree to which the samples
are representative of the material.
MEASUREMENT ACCURACY AND QUALITY ASSURANCE
A3.5 Adequate confidence in the results of analyses is ensured if the samples are
analysed at a suitably accredited laboratory and if the level of accuracy of the
analytical technique is commensurate with the activity concentration criterion against
which the material is being checked. If an accredited laboratory is not available, the
analytical techniques can at least be validated against appropriate reference materials.
Problems due to cross-contamination between samples and contamination of
equipment can be avoided by exercising an appropriate level of care during sampling
and at the laboratory.
A3.6 The distribution of activity concentrations in a material may span an order of
magnitude or more. In order not to distort the distribution at the low end, the lower
limit of detection (LLD) needs to be sufficiently below the activity level against which
the measurements are being compared. For instance, when a material is being
compared with the 1 Bq/g activity concentration value, an LLD of 0.1 Bq/g would be
appropriate.
ANALYTICAL TECHNIQUES
A3.7 Having defined the main radionuclides of interest and the required
measurement sensitivity, appropriate analytical protocols can be considered. Analysis
techniques for determining activity concentrations of individual radionuclides in solid
materials can be time-consuming and expensive. The techniques employed for a
particular sample therefore need to be chosen judiciously.
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A3.8 For general screening of the total radioactivity it is often adequate to perform
gross alpha–beta counting, applying suitable corrections for self-absorption. It is a
relatively quick and inexpensive technique for determining the total activities of the
alpha emitting and beta emitting radionuclides, from which the ratio of the two can be
obtained. On its own, this technique does not give reliable information on individual
radionuclides. However, the alpha–beta ratio can provide clues as to the radionuclide
composition, which may be useful in deciding upon subsequent analysis steps.
Obviously, if the total activity concentration is less than the activity concentration
criterion for individual radionuclides, then no further analysis is necessary. Counting
times are selected to obtain the required LLD for the materials concerned (i.e. about
10% of the applicable activity concentration level).
A3.9 For analysis of the individual radionuclides of interest, the following analytical
techniques can be applied:
X ray fluorescence (XRF) spectrometry:
o The XRF method is widely used to measure the elemental composition of
materials, and is well suited to the rapid determination of uranium and
thorium. There are two types of spectrometer, both of which can be used
for this application:
Wavelength dispersive spectrometers, in which photons are
separated by diffraction on an analysing crystal before being
detected;
Energy dispersive spectrometers, in which the detector allows the
determination of the energy of the photon when it is detected; these
spectrometers are smaller and cheaper than wavelength dispersive
spectrometers, and the measurement is faster, but the resolution
and detection limit are not as good.
Inductively coupled plasma atomic emission spectroscopy (ICP-AES):
o ICP-AES is used for the chemical analysis of aqueous solutions of rocks
and other materials, and is suitable for the determination of a wide range
of major elements and a limited number of trace elements.
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o Sample preparation involves the digestion of the powdered material with
40% v/v hydrofluoric acid mixed with either perchloric or nitric acid.
Some minerals such as chromite, zircon, rutile and tourmaline will not
completely dissolve using this digestion procedure. For samples containing
substantial amounts of these minerals, XRF analysis is probably more
appropriate.
Inductively coupled plasma mass spectroscopy (ICP-MS):
o ICP-MS is used to determine trace elements in aqueous solutions. The
technique is well suited for determination of uranium and thorium. The
sample preparation procedure is the same as that for ICP-AES.
High energy gamma spectrometry (high purity germanium crystal (HPGe)):
o This technique provides a quantification of the important radionuclide
226Ra, along with 228Ra and 228Th. The method can also be used to
quantify the 238U concentration, but with a higher LLD.
Low energy gamma spectrometry (HPGe):
o This technique entails a relatively short counting time of 4 h, and gives a
quantification of 238U and 210Pb (as well as 235U). It is possible for the
technique to also provide a determination of 226Ra (as well as
radionuclides of lesser interest: 227Ac, 231Pa and 230Th), but with a
higher LLD.
Sample digestion and alpha spectrometry:
o This technique is suitable for quantifying the 210Po concentration. It
involves a relatively long counting time.
The application of the above mentioned techniques is summarized in Table 5.
The minimum sample size needed is in each case about 10 g. When using the first four
techniques, the following conversions from ppm to Bq/g are required:
ThgBq0.004057thoriumppm1
UgBq012348.0uraniumppm1
232
238
A3.11 For material associated with most industrial processes it is adequate to have a
basic analytical infrastructure consisting of XRF in combination with a background
shielded thin-window HPGe gamma spectrometry system. Only in those processes
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where 210
Po is of concern will radiochemical techniques in combination with alpha
spectrometry be required. Although 40
K is unlikely to be of concern (see Section 3.3),
its activity concentration can be determined at no additional cost, especially if both
XRF and gamma spectrometry are used for radionuclide analyses. This may be useful
when 40
K is present in significant concentrations, since it can be used to deduce
information on other radionuclides and to improve the quality assurance of the
measurements.
TABLE 5. ANALYTICAL TECHNIQUES FOR DETERMINING
RADIONUCLIDE ACTIVITY CONCENTRATIONS
Radionuclide Suitable
technique Comment
238U,
232Th
(and 40
K)
XRF,
ICP-AES,
ICP-MS
Sensitivity of 1 ppm uranium or thorium achievable
with any of these techniques (equivalent to about 0.01
Bq/g 238
U and 0.004 Bq/g 232
Th)
226Ra,
228Ra,
228Th
(and 40
K)
High energy
gamma
spectrometry
(i) The presence of uranium may interfere with the
direct determination of 226
Ra
(ii) For indirect determination of 226
Ra, gas-tight
sealing for 3 weeks is needed to ensure equilibrium
with progeny (214
Pb, 214
Bi)
(iii) LLD of 0.1 Bq/g requires equipment that is well
shielded from background radiation
(iv) High sensitivity (>25%) and high resolution HPGe
detectors required
(v) Counting times of a few hours per sample will be
adequate
(vi) High density materials (>2.5 g/cm3) may need
self-absorption corrections
210Pb Low energy
gamma
spectrometry
(vii) Self-absorption corrections required
(viii) LLD of 0.1 Bq/g requires equipment that is
well shielded from background radiation
(ix) Counting times of a few hours per sample will be
adequate
210Po Sample digestion
+ alpha
spectrometry
(x) Microwave acid digestion required
(xi) Validated radiochemical separation techniques
required
(xii) Counting times of a few hours per sample will be
adequate to achieve an LLD of 0.1 Bq/g
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