Post on 26-Apr-2020
SAFRAN
Version 2 will be released in
August 2013
Rodolfo Avila, Facilia AB
Outline
• Overview of SAFRAN
• Enhancements to support safety assessments
for the management of DSRSs and the Borehole
Disposal Concept (BDC)
• Generic Operational Safety Assessment
(GOSA) for the management of DSRSs
What is SAFRAN
• SAFRAN is a software package for safety
assessment in pre-disposal waste
management.
• It implements the methodology developed
within the IAEA project SADRWMS (2005-
2010)
SADRWMS
methodology
Assessment Context
Description of Facility or Activity and the Waste
Identification of Hazards
Development and Justification of Scenarios
Identification of Scenarios
Formulation of Models and Identification of Data Needs
Evaluation of Results
Analysis of Safety Measures
Analysis of Engineering
Performance of Calculations
Comparison with Assessment Criteria
Engineering design, Safety measures,
Other relevant information (management systems, operational
experience, site data …)
Models and computer codes; Generic / site specific data
Purpose, Regulations, Standards …
PIE lists, Expert judgements
Screening of Hazards
Review and
modify
Adequate? Accept Independent verification
Yes Yes No
No
Adequate?
Provides detailed
guidelines for safety
assessment.
Based on the IAEA
safety guide DS284
(GSG-3): The Safety
Case and Safety
Assessment for
Predisposal Management
of Radioactive Waste
The SADRWMS methodology
• Provides detailed advice for each step of the
Safety Assessment
• Describes the different types of
assessments that might be required
• Provides methods for Hazard identification
and screening
• Provides methods for performing qualitative
and quantitative assessments for different
scenarios
SAFRAN components
System description Site features, waste
producers, waste streams
Regulatory
Framework
Safety Assessment Normal Operation,
Accidents
SAFREQ
SAFCALC DATABASE
Report
Report
System Description
For each configuration
• Site
• Facilities
– Rooms
» Areas (Storage or Processing)
Safety elements
• Waste Management Activities
– Processes
– Check for clearance
• Waste Producers
– Primary Waste Components
» Waste Streams
Safety elements
• Site selection
• Safety functions
• Limits and conditions
• Mantainance requirements
• Operational procedures
• Emergency procedures
• Management systems
Can be linked to physical elements and
assessments
Waste management activities
• Description
• Output(s) from activities
• Reduction factors
• One and only one WMA can be assigned
to an area
A process is a sequence of WMAs which can
be used in defition of Waste Streams (WS)
Waste Streams
• Waste streams represent the fate of waste
components through different steps of
processing, storing and clearing of wastes
• Accounting for changes in waste properties
by waste management activities at each
step.
Enhancements for application to DSRS
• Different forms for Sources, Solid and Liquid waste.
• Table with inventory of sources
• Library of sources
• Individual sources are traced in a project
• Possibility to calculate dose rates for WCs
• A library of safety elements of relevance for the safe
management of sources
• A library of pre-disposal waste management activities
• A library of typical processes for management of sources
• Incorporation of SIMBOD (Source Inventory Management
for Borehole Disposal) is an inventory tracking database
tool.
SAFRAN components
System description Site features, waste
producers, waste streams
Regulatory
Framework
Safety Assessment Normal operation,
accidents
SAFREQ
SAFCALC DATABASE
Report
Report
Assessment types
• For normal operation and accidents.
• Doses to workers and members of the
public.
• Radiological impacts indoors and outdoors.
Graded approach to the assessments
Impacts
Screening or
Hazards
Dose
Assessment
Calculations of Hazard
Quotients (HQ) for
standardized conservative
exposure situations
calculations for specified
endpoints and expecific
exposure conditions
Assessments for accidents
Impact 1
PIE Type
PIE 1 PIE n
Scenario 1 Scenario n
Impact n
Endpoint 1 Endpoint n
Ass Case 1
Ass Case n
Scenario m
Impact m
Screening of hazards
Example of Probability-Consequence plots
HQ/Prob Very
Low
Low Medium High Very
High
<0.1 SC3
0.1- 1 SC4
1-10 SC2
10-100
>100 SC1
Enhancements for application to DSRS
• Update of the PIE database
• Library of typical scenarios
• Library of generic safety assessments
• Wizard for performing the assessments step
by step – eLearning module
SAFRAN components
System description Site features, waste
producers, waste streams
Regulatory
Framework
Safety Assessment Normal operation,
accidents
SAFREQ
SAFCALC DATABASE
Report
Report
Models available in SAFCALC
• IAEA SR-19 models: screening models for
routine releases to the atmosphere, lakes,
rivers, estuarines and coastal areas.
• Model for accidental releases to the
atmosphere.
• Model for accidental releases inside a room.
• Simple dosimetry models: point source, disc,
cylinder, cube (with and without shielding)
SAFRAN components
System description Site features, waste
producers, waste streams
Regulatory
Framework
Safety Assessment Normal operation,
accidents
SAFREQ
SAFCALC DATABASE
Report
Report
Database
• Radionuclide half lives.
• Clearance levels.
• Gamma constants – dose rates at 1 m from a point source.
• Screening dose rates for Normal and accidental situations.
• Screening release rates for Normal operation.
• Screening releases for accidental situations.
• Release Fractions.
• Dispersion factors.
• Dose Conversion Factors for Normal and accidental
situations.
Additions for BOSS
• Models and calculation methods used in Generic
Operational Safety Assessment (GOSA).
• Parameter values required for GOSA.
SAFRAN components
System description Site features, waste
producers, waste streams
Regulatory
Framework
Safety Assessment Normal operation,
accidents
SAFREQ
SAFCALC DATABASE
Report
Report
SPECIALIZED LIBRARIES FOR BOSS
SAFREQ
• Tool for assistance in developing the safety
case by assessing compliance with Safety
Requirements and Safety Guidelines.
GENERIC OPERATIONAL SAFETY
ASSESSMENT (GOSA)
Assessment Context
• The assessment context of the GOSA
should be consistent with the generic safety
assessment (GSA) for borehole disposal
(IAEA Safety Series Report: Generic Post-
Closure Safety Assessment for Borehole
Disposal of Disused Sealed Sources)
Purpose
• The purpose of the GOSA is to demonstrate that
the proposed pre-disposal waste management
activities are done in a safe manner, as required
by the regulatory framework. The safety of
operators (workers) and members of the public will
be assessed, both for normal operations and for
potential accidental situations.
Scope
• The starting point for the GOSA is that the Disused Sealed
Sources (DSSs) have arrived at the site.
• Activities of the original producer [e.g. hospital] and
transport to site are beyond the scope of the current
project).
• Different disposal options (storage for decay, disposal in a
near-surface or deep facility, BDC) and management
options (long-term storage) will be considered.
Inventory to be considered
• The inventory (Bq) and number of sources to be assessed
in the GOSA need to be representative of what is found in
practice in different countries.
• An initial proposal is to consider two cases: a country
(Ghana being an example) with a low to medium inventory
of relatively low level activity sources that do not require the
use of hot cells, and a country (South Africa being an
example) with a medium to large inventory which includes
high activity sources that will require the use of hot cells. • Different initial states of the sources should be considered,
including sources in the original devices, in a transport
package, in the working container, and conditioned in
cement.
Regulatory Framework
• IAEA Safety Standards will be used as the basis
for the regulatory framework.
• This will include normal operation and accidental
situations, taking into account dose constraints as
well as dose limits.
• Doses to the eye, extremities, etc., in addition to
whole body doses, will be calculated.
Inventory of sources
Sources for Disposal
Sources for Decay Store
Classification of sources
Other Disposal Options
Sources for BDC
Screening on total
inventory
Several Boreholes might be required
Number of capsules required for one borehole
Allocation of Sources to capsules
Use SAFCALC to obtain operational activity limits for capsules
WMA, etc
IAEA databases, SIMBOD, etc
Temporary Storage at Site
Prepare for Introduction into Cell
Remove Source and Characterise
Lift original Source Shield into Cell
Close Cell
Encapsulation and Testing
Condition into Disposal Container
Lower into Borehole
Borehole Backfilling
Transfer Container to Transfer Cask
Lower into Borehole
Borehole Backfilling
Operational activities Duration
(Minutes)
1) Prepare for Introduction into hot cell 15
2) Lift Original Source Shield into the hot cell 5
3) Close the hot cell 20
4) Remove the source 60
5) Characterise the source 20
6) Encapsulation and test of the capsule 20
7) Place capsule in disposal container and NDT 20
8) Transfer disposal container to the transfer cask 10
9) Disengage and prepare the transport cask for
transport
15
10) Emplacement of the disposal container in borehole 15
11) Backfilling of the borehole 15
Typical activities for operational phase of the BDC
Examples of accidental scenarios (hot cell)
• The situation where the operation team is unaware that the source has an
activity greater than the value for what the facility was designed for and the
team proceeds with standard operations.
• Error during the determination of the density of the shielding material (sand) in
the hot cell and the operation proceeds with a sand density below design
requirements.
• Situation with the ZnBr2 window density below design requirements being used
by the operation team.
• Source is dropped after being removed from the original source shield.
• The source is found to be leaking when removed from the original source shield
inside the hot cell. (Could have been damaged during removal).
• The manipulators malfunction whilst the source is inside the hot cell.
• The biological shield is damaged while bringing in the original source shield.
• Power outage in the hot cell.
• Lights are not operational in the hot cell.