General Nuclear System Ltd....PC CREAM 08, Health Protection Agency, HPA-RPD-58,November 2009. [6]...

UK Protective Marking: Not Protectively Marked


Revision Approved by Number of

Pages

001-1 211

Approval Date

General Nuclear System Ltd.

UK HPR1000 GDA Project

Document Reference: HPR/GDA/PCER/0007

Title:

Pre-Construction Environmental Report Chapter 7

Radiological Assessment

This document has been prepared on behalf of General Nuclear System Limited with the support of China General Nuclear Power Corporation (CGN) and Électricité de France S.A. (EDF).

Although due care has been taken in compiling the content of this document, neither General Nuclear System Limited, CGN, EDF nor any of their respective affiliates accept any liability in respect to any errors, omissions or inaccuracies contained or referred to in it.

P206118图章

P206118图章

UK HPR1000 GDA

Pre-Construction Environmental Report Chapter 7 Radiological Assessment


Rev: 001-1 Page: II


DISTRIBUTION LIST

Recipients Cross Box

General Nuclear System Executive ☐

General Nuclear System all staff ☐

General Nuclear System and BRB all staff ☒

CGN ☒

EDF ☒

Regulators ☒

Public ☒

UK HPR1000 GDA



Rev: 001-1 Page: 1 / 209


TABLE OF CONTENTS

7.1 List of Abbreviations and Acronyms .................................................................... 3

7.2 Introduction ............................................................................................................ 4

7.3 Regulatory Context ................................................................................................ 6

7.3.1 Legislative Background ................................................................................. 6

7.3.2 Radioactive Substances Regulation Guidance ............................................... 7

7.4 Common Assumptions on the Generic Site ......................................................... 9

7.5 Direct Dose .............................................................................................................. 9

7.5.1 Methodology ................................................................................................ 10

7.5.2 Input Data .................................................................................................... 10

7.5.3 Results and Discussion ................................................................................ 11

7.6 Dose to the Most Exposed Members of the Public ............................................ 12

7.6.1 Overview of the Radiological Assessment Methodologies ......................... 12

7.6.2 Stage 1 Assessment ...................................................................................... 14



7.7 Annual Dose to the Representative Person ........................................................ 27

7.7.1 Methodology ................................................................................................ 27

7.7.2 Input Data .................................................................................................... 28


7.8 Potential Dose due to the Short-term Discharge ............................................... 30

7.8.1 Methodology ................................................................................................ 30

7.8.2 Input Data .................................................................................................... 33


7.9 Comparison of the Calculated Doses with Relevant Dose Constraints ........... 39

7.10 Environmental Accumulation ........................................................................... 45

UK HPR1000 GDA



Rev: 001-1 Page: 2 / 209


7.10.1 Methodology .............................................................................................. 45

7.10.2 Input Data .................................................................................................. 48

7.10.3 Results and Discussion .............................................................................. 48

7.11 Assessment of Collective Dose ........................................................................... 50

7.11.1 Methodology .............................................................................................. 50

7.11.2 Input Data ................................................................................................... 51

7.11.3 Results and Discussion............................................................................... 51

7.12 Potential Dose Rate to Non-human Biota ........................................................ 53

7.12.1 Methodologies ........................................................................................... 53

7.12.2 Input Data .................................................................................................. 54

7.12.3 Results and Discussion .............................................................................. 56

7.13 Uncertainty and Variability .............................................................................. 57

7.14 Conclusions ......................................................................................................... 60

7.15 References ........................................................................................................... 62

Appendix 7A Results of Radiological Assessment ................................................... 66

Appendix 7B Other Tables ...................................................................................... 193

UK HPR1000 GDA



Rev: 001-1 Page: 3 / 209


7.1 List of Abbreviations and Acronyms ADMS Atmospheric Dispersion Modelling System

BAT Best Available Technique

BSSD Basic Safety Standards Directive

CGN China General Nuclear Power Corporation

DPUR Dose Per Unit Release

EA Environment Agency (UK)

EMCL Environmental Media Concentration Limit

EPR16 Environmental Permitting Regulations 2016 (England and Wales)

ERICA

Environmental Risk from Ionising Contaminants: Assessment and Management

FSA Food Standards Agency

GDA Generic Design Assessment

HPA Health Protection Agency (UK)

HPR1000 (FCG3)

Hua-long Pressurised Reactor under construction at Fangchenggang nuclear power plant unit 3

IAEA International Atomic Energy Agency

ICRP International Commission on Radiological Protection

IRA Initial Radiological Assessment

NHB Non-human Biota

NRPB National Radiological Protection Board (UK)

OPEX Operating Experience

P&ID Process and Information Document for Generic Assessment of Candidate Nuclear Power Plant Designs

PC-CREAM Personal Computer version of Consequences of Radiological Emissions Assessment Methodology

PCER Pre-Construction Environmental Report

PHE Public Health England

UK HPR1000 GDA



Rev: 001-1 Page: 4 / 209


RQ Risk Quotient

UF Uncertainty Factor

UK HPR1000 UK version of the Hua-long Pressurised Reactor

7.2 Introduction This chapter presents information pertaining to the likely impact on the environment and members of the public on the generic site from radioactive discharges and direct radiation arising from the normal operation of the UK version of the Hua-long Pressurised Reactor (UK HPR1000). It notably provides the information required by Environment Agency (EA) during the Generic Design Assessment (GDA) stage as set out in item 7 of Table 1 of the Process and Information Document for Generic Assessment of Candidate Nuclear Power Plant Designs (P&ID) in Reference [1], which comprises the following：

• annual dose to most exposed members of the public for liquid discharges;

• annual dose to most exposed members of the public for gaseous discharges (identifying separately the dose associated with on-site incineration where applicable);

• annual dose to the most exposed members of the public for all discharges from the facility;

• annual dose from direct radiation to the most exposed member of the public;

• annual dose to the representative person for the facility;

• potential short-term doses, including via the food chain, based on the maximum anticipated short-term discharges from the facility in normal operation;

• a comparison of the calculated doses with the relevant dose constraints;

• an assessment of whether the build-up of radionuclides in the local environment of the facility, based on the anticipated lifetime discharges, might have the potential to prejudice legitimate users or uses of the land or sea;

• collective dose truncated at 500 years to the UK, European and world populations;

• dose-rate to non-human species.

The radiological impact assessment in this document is also conducted to demonstrate that the UK HPR1000 complies with the requirements of The Environmental Permitting (England and Wales) Regulations 2016 (EPR16) (as amended 2018) in Reference [2].

During GDA process, the radiological impact assessments from maximum annual discharges and direct radiations during normal operation of the UK HPR1000 have

UK HPR1000 GDA



Rev: 001-1 Page: 5 / 209


been conducted to estimate the prospective radiological impact on members of the public and the Non-Human Biota (NHB). The collective dose, the potential impacts on the surrounding land due to the accumulation of radioactive discharges and the potential radiological impact of short-term discharges have also been assessed. All these radiological impact assessments are based on one unit of UK HPR1000 unit operating for 60 years at a generic site.

This document also reflects the updated information since the step 3 of GDA, such as, the UK HPR1000’s maximum annual discharges have been revised based on the enrichment of the Operating Experience (OPEX) data and refinement of expected events contribution, the guidance related to short-term dose assessment has been updated and the Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) tool has been improved from version 1.2, etc.

The content of this chapter is developed based on the design reference version 2.1 plus the list of modifications, as described in the Sub-chapter 1.4.4 of PCER Chapter 1.

The following tools or methods are used to estimate the impact of radioactive discharges on members of the public and NHBs:

a) The Initial Radiological Assessment (IRA) tool in Reference [3] and [4] is used to undertake an initial cautious prospective assessment of the dose to members of the public arising from radioactive wastes discharged to the environment;

b) Personal Computer version of Consequences of Radiological Emissions Assessment Methodology (PC-CREAM) 08, Reference [5], is used for conducting realistic prospective assessment of public dose, collective dose and assessing impact of the accumulation of radioactive material in the environment from continuous discharges;

c) The gaseous dispersion model in Atmospheric Dispersion Modelling System (ADMS) 5, Reference [6], is used to calculate the activity concentrations in air, deposition rate on land and the cloud gamma doses per unit discharge for short-term discharges;

d) ERICA, Reference [7], and the Ar-Kr-Xe calculation tool, Reference [8], are used for the NHBs radiological impact assessment arising from continuous sources of radioactive waste discharged to the environment.

This chapter has a number of interfaces with other chapters of Pre-Construction Environmental Report (PCER), which are presented in T-7.2-1.

UK HPR1000 GDA



Rev: 001-1 Page: 6 / 209


T-7.2-1 Interface with Other PCER Chapters

Chapter Interface Relationship

PCER Chapter 1 Introduction

PCER Chapter 1 provides the summary of each PCER chapter and the P&ID route map.

PCER Chapter 2 Generic Site Description

PCER Chapter 2 provides generic site description to support the radiological impact assessment.

PCER Chapter 3 Demonstration of BAT

PCER Chapter 7 is an important input to identify the aspects that needs to be (further) optimised and

provides the evaluation of the impact of radiological discharges on members of the public and non-human biotas to support the demonstration of Best Available

Technique (BAT) presented in PCER Chapter 3.

PCER Chapter 6 Quantification of

Discharges & Limits

PCER Chapter 6 provides maximum annual discharges (i.e. proposed limits) and short-term release used as

input for PCER Chapter 7. PCER Chapter 7 provides the radiological impact

assessment results based on maximum annual discharges to support the selection of significant

radionuclides for PCER Chapter 6.

7.3 Regulatory Context 7.3.1 Legislative Background

The Euratom Basic Safety Standards Directive (BSSD) (1996) in Reference [9] provides the mechanism for the implementation of the 1990 recommendations of International Commission on Radiological Protection (ICRP) in Reference [10]. It was revised into the BSSD (2013), Reference [11], to reflect the requirements of the 2007 ICRP recommendations, in Reference [12].

The EPR16 (as amended 2018), Reference [2], transfers components of the BSSD (2013) into UK domestic legislation. This legislation mainly requires that the appropriate environment agencies, when exercising their duties and functions under radioactive substances legislation, ensure that:

a) All public ionising radiation exposures from radioactive waste disposals are kept as low as reasonably achievable, with economic and social factors taken into account;

b) The sum of the doses arising from such exposures does not exceed the individual public dose limit of 1 mSv/y;

UK HPR1000 GDA



Rev: 001-1 Page: 7 / 209


c) The dose does not exceed 0.3 mSv/y from any source from which radioactive discharges are first made on or after 13th May 2000;

d) The dose does not exceed 0.5 mSv/y from the any single site discharges.

In addition to the permitting requirements, the UK has produced a strategy for discharges in Reference [13] which requires the application of BAT in England and Wales to ensure that discharges from new nuclear power stations constructed in the UK do not exceed those from comparable power stations across the world.

The Health Protection Agency (HPA) (now known as Public Health England (PHE)) has suggested a dose constraint of 0.15 mSv/y for any new nuclear power station, Reference [14]. However, this is not currently enacted into UK legislation.

7.3.2 Radioactive Substances Regulation Guidance

The Radioactive Substances Regulation Environmental Principles in Reference [15] provides the objective for radioactive substances regulation, fundamental principles and generic developed principles for the protection of people and the environment against radioactive material, which includes:

a) RPDP2: Radiation doses to individual people shall be below the relevant dose limits and in general should be below the relevant constraints;

b) RPDP3: NHBs should be adequately protected from exposure to ionising radiation;

c) RPDP4: Assessments of potential doses to people and to non-human species should be made prior to granting any new or revised permit for the discharge of radioactive wastes into the environment.

The EA, Scottish Environment Protection Agency and the Department of Environment in Northern Ireland (now Northern Ireland Environment Agency) in collaboration with the Food Standards Agency (FSA) and National Radiological Protection Board (NRPB) have developed and published principles and guidance for prospective assessment of public doses in the Reference [16]. This guidance sets out 13 general dose assessment principles, and several important principles for the prospective assessment of doses, which include 9 principles relevant to GDA stage and 4 principles relevant to site specific stage:

a) Principles relevant to GDA stage

1) Prospective dose assessment methods, data and results should be transparent and made publicly available;

2) When determining discharge permits or authorisations, the dose to the representative person should be assessed;

3) Doses to the most affected age group should be assessed for the purpose of

UK HPR1000 GDA



Rev: 001-1 Page: 8 / 209


determining discharge permits or authorisations. Assessment of doses to 1 year old, 10 year old and adults (and fetus when appropriate) provides adequate age group coverage;

4) The dose to the representative person which is assessed for comparison with the source constraint and, if appropriate, the site constraint, should include all reasonably foreseeable and relevant future exposure pathways;

5) Where a cautious estimate of the dose to the representative person exceeds 0.02 mSv/y, the assessments should be refined and, where appropriate, more realistic assumptions made. However, sufficient caution should be retained in assessments to provide confidence that actual doses received by the representative person will be below the dose limit;

6) The assessment of dose to the representative person should take account of accumulation of radionuclides in the environment from future discharges;

7) The dose assessed for operational short term release at notification levels or limits should be compared with the source constraint (maximum of 0.3 mSv/y) and the dose limit (1 mSv/y), taking into account remaining continuous discharges during the remainder of the year and contributions from other relevant sources under control;

8) For permitting or authorisation purposes, collective doses to the populations of UK, Europe and the world, truncated at 500 y, should be estimated;

9) Where the assessed mean dose to the representative person exceeds 0.02 mSv/y, the uncertainty and variability in the key assumptions used for the dose assessment should be reviewed.

b) Principles relevant to site specific stage

1) Workers, who are exposed to discharges of radioactive waste, but who do not work directly with ionising radiation and are therefore not normally exposed to ionising radiation, should be treated as if they are members of the public for the purpose of determining discharge permits or authorisations.

The information related to workers in and around the UK HPR1000 site is highly site specific and is difficult to adequately (i.e. with an appropriate level of uncertainty) determine during GDA stage. This principle is therefore not considered during GDA.

2) Significant additional doses to the representative person from historical discharges from the source being considered and doses from historical and future discharges and direct radiation from other relevant sources subject to control should be assessed and the total dose compared with the dose limit of 1 mSv/y.

The dose assessments are based on the prospective discharges from a single UK HPR1000 unit, the historical discharges and other relevant sources are highly site

UK HPR1000 GDA



Rev: 001-1 Page: 9 / 209


specific, therefore not considered.

3) The realistic habits adopted for the representative person should be those which have actually been observed at the site, within a period of about 5 years. Changes to habits which are reasonably likely to occur should be taken into account.

In GDA stage, bounding site information is considered. The actual site data will be determined (with due consideration of this principle) and used once the site will be selected, i.e. during site licensing phase.

4) Principle 10 Land use and infrastructure should have sufficient capacity to support the habits of the representative person. Any changes to land use and infrastructure should be reasonably likely to occur over a period of about 5 years and be sustainable year on year for them to be considered.

In GDA stage, bounding site information is considered. The actual site data will be determined (with due consideration of this principle) and used once the site will be selected, i.e. during site licensing phase.

7.4 Common Assumptions on the Generic Site According to the description in PCER Sub-chapter 2.4, the established UK HPR1000 generic site can represent the potential sites identified in the UK Government’s National Policy Statement for Nuclear Power Generation (EN-6), Reference [17].

The main assumptions about the generic site for the UK HPR1000 are:

a) The site is in a coastal or estuarine location and the topography of the site is flat;

b) There is no water extraction from aquifers and no standing water on the site;

c) There are no freshwater bodies on or adjacent to the site;

d) The nearest human receptors are assumed to be a fisherman family and local resident family ;

e) Discharge routes are assumed to be gaseous/airborne aerial discharges to the atmosphere and liquid discharges to the marine/estuarine environment adjacent to the site;

f) There are no adjacent sites considered during GDA stage;

g) No incinerator is planned to be built on site.

The layout of the UK HPR1000 is shown in PCER Sub-chapter 2.4.

7.5 Direct Dose The direct dose is an important component to the overall doses received by both the most exposed groups as well as the representative person. This section describes how the direct dose is calculated, the input used and the results.

UK HPR1000 GDA



Rev: 001-1 Page: 10 / 209


7.5.1 Methodology

It is difficult to measure the doses from direct radiation as they have to be distinguished from the dose associated with other discharge routes as well as from natural radiation. There is also no available data from UK HPR1000 plants or from HPR1000 (FCG3) which is the UK HPR1000 reference plant. Therefore, the direct doses from sources on the UK HPR1000 generic site are estimated by the following two steps:

• Step 1, where the sources on site are simulated, at specific distances, and the dose rates calculated using a Monte Carlo code, which is broadly used for direct dose assessment of nuclear plants in UK.

• Step 2, where doses to members of the public are calculated from Step 1 using assumed habit data. The overall dose at the receptor location is equal to the dose rate at this location multiplied by the exposure time, taking into account the reduced dose rate while indoors, which is presented as:

Direct Dose (µSv/y) = D × T × [(LFo × Fo) + (LFi ×Fi)] (7.5-1) Where:

D: External dose rate (from Step 1), μSv/h;

T: Occupancy time, h/y;

LFo: Location factor for being outdoors;

LFi: Location factor for being indoors;

Fo: Fraction of time spent outdoors; and,

Fi: Fraction of time spent indoors.

7.5.2 Input Data

a) Dose rates

The sources on site, with the potential direct radiation to members of the public, include the Reactor Building, the Radioactive Waste Treatment Building, the Fuel Building, the Nuclear Auxiliary Building, the Interim Storage Facility for Intermediate Level Waste and the Spent Fuel Interim Storage. The sky scattering radiation and ground scattering radiation are also included in the calculation of dose rate, and the detailed calculation methodology and assumptions of the whole sources on site are presented in Public dose evaluation from direct radiation topic report, Reference [18].

b) Distance to direct radiation source

The general layout of the UK HPR1000 is site specific, as it is impacted by the

UK HPR1000 GDA



Rev: 001-1 Page: 11 / 209


topography, geology, meteorology, transport conditions and other factors of the future site. The future site layout will be designed to minimise land usage, simplify construction, increase operational efficiency, and minimise public dose. In GDA stage, the layout of the UK HPR1000 cannot be accurately described, it is therefore conservatively assumed that members of the public are located at 100 m from these facilities.

The dose rates at 100 m from these facilities are calculated with assumption that members of the public are at 1 metre above the ground, cf. T-7B-1.

c) Habits data

The habits data of members of the public related to direct dose assessment such as the occupancy time, location factor and fraction of time indoors and outdoors, is presented in T-2.4-5 of PCER Chapter 2.

7.5.3 Results and Discussion

According to the Equation (7.5-1) and the input data presented in Sub-chapter 7.5.1 and 7.5.2, the direct doses to adult, child and infant are presented in T-7.5-1.

T-7.5-1 Total Direct Doses to the Different Age Groups

Facilities Adult Dose

(μSv/y) Child Dose

(μSv/y) Infant Dose

(μSv/y) Reactor Building 2.1E-02 1.1E-02 7.3E-03 Nuclear Auxiliary

Building 3.8E-02 1.9E-02 1.3E-02

Fuel Building 2.2E-02 1.1E-02 7.7E-03 Radioactive Waste Treatment Building

1.7E-01 8.6E-02 5.9E-02

Interim Storage Facility for

Intermediate Level Waste

7.6E-01 3.9E-01 2.6E-01

Spent Fuel Interim Storage Facility

5.3E+00 2.7E+00 1.8E+00

Total 6.3E+00 3.2E+00 2.2E+00

The total direct doses to the adult, child and infant are 6.3 µSv/y, 3.2 μSv/y and 2.2 μSv/y, respectively.

The adult group receives the highest dose from direct radiation, i.e. 6.3 µSv/y, due to the outdoor occupancy time being longer for this group compared to the child and infant groups.

UK HPR1000 GDA



Rev: 001-1 Page: 12 / 209


7.6 Dose to the Most Exposed Members of the Public 7.6.1 Overview of the Radiological Impact Assessment Methodologies

A staged approach to the assessment of dose to members of the public is recommended in Reference [16]. The IRA methodology and associated tool used for the first two stages of dose assessment have been developed to calculate doses in a simple and cautious manner. For stage 3 dose assessment, a detailed and flexible method for which input data can be defined by users, is needed, and PC-CREAM 08 is a suitable method that is widely used in the UK. The process of this staged approach are summarised below:

a) Stage 1 – Initial radiological assessment using default data within IRA methodology. If assessed dose is >20 μSv/y, then proceed to stage 2 assessment;

b) Stage 2 – Initial radiological assessment using refined data within IRA methodology. If assessed dose is >20 μSv/y, then proceed to stage 3 assessment;

c) Stage 3 – Realistic radiological impact assessment using refined generic site parameters.

Dose assessments to the most exposed members of the public are also included in China General Nuclear Power Corporation (CGN)’s radiological impact assessment. However, CGN’s methodology cannot be used for UK HPR1000 as it differs from the approach used in UK:

1) CGN’s methodology is developed to reflect relevant Chinese guidance, Reference [19], which requires a collective dose assessment to members of the public who live within the 80 km around the site. Therefore this methodology is not appropriate to be used for calculating the collective dose to the UK, the EU and the whole world;

2) The methodology highly relies on site specific data such as meteorological data, habit data, demography, and cloud standard deviations etc., these are not available during the GDA process.

7.6.1.1 IRA Methodology

The IRA methodology used in the stage 1 and stage 2 radiological impact assessments is based on the Dose Per Unit Release (DPUR) values in Reference [3] for different radionuclides, different release routes and different exposure pathways. The initial doses to members of the public are calculated by multiplying the DPUR values by the maximum annual discharges and, for stage 2 only, by scaling factors.

The IRA methodology is appropriate for the initial radiological impact assessment of the UK HPR1000 as:

a) IRA methodology is recommended in the P&ID, Reference [1], and is in line with

UK HPR1000 GDA



Rev: 001-1 Page: 13 / 209


Relevant Good Practice. It is a staged approach for the first two stages of radiological impact assessments commonly used for GDA dose assessment;

b) IRA has been developed to facilitate conducting a simple and cautious assessment of the dose to the most exposed group:

1) The DPUR values have been derived for 4 discharge scenarios (discharge to air, estuary/coastal water, river and sewer), 100 radionuclides and 7 exposure groups, and include a total of 41 exposure pathways;

2) The DPUR values presented in the IRA methodology are the highest DPUR factors for each radionuclide regardless of the age group, thus the dose to a specific age group is conservative;

3) IRA methodology is based on exposure pathways and groups which are likely to be the worst affected for a particular discharge route.

7.6.1.2 PC-CREAM 08

The PC-CREAM 08 is a computer code comprising a suite of models and data that was developed by HPA (now PHE) and tailored to UK legislative requirements. It is deemed that PC-CREAM 08 used in the stage 3 assessment is an appropriate method as it has been verified against environment data as described in Reference [5] and is widely used for many radiological impact assessments in the UK.

PC-CREAM 08 consists of a number of sub modules. The main divisions of the program are “Models” and “ASSESSOR”. The “Models” includes a series of mathematical modules used to predict the transfer of radionuclides through the environment and estimate the activity concentrations in various environmental media following a continuous release, Reference [5]. These modules are:

• The Atmospheric Dispersion Module (PLUME);

• The Ground Gamma Module (GRANIS) provides the transfer of radionuclides through the soil and gamma radiation from radionuclides deposited on the ground;

• The Foodchain Module (FARMLAND) provides the transfer of radionuclides into terrestrial foods following deposition onto the ground;

• The Resuspension Module (RESUS) provides the estimation of the activity concentrations in air arising from the resuspension of previously deposited radionuclides;

• The Marine Dispersion Module (DORIS).

The outputs of these modules are then put into the dose assessment part of the program, “ASSESSOR”, to enable the assessment of the individual and collective dose for the UK, European and the whole world due to gaseous and liquid discharges.

UK HPR1000 GDA



Rev: 001-1 Page: 14 / 209


7.6.2 Stage 1 Assessment

7.6.2.1 Methodology

a) Liquid discharges

The fisherman family is identified as the most exposed group for liquid discharges in the IRA methodology. The relevant pathways include:

1) External exposure from radionuclides deposited on shore sediments; and

2) Internal exposure through consumption of seafood incorporating radionuclides with conservative habits.

Inhalation of sea spray, inhalation of resuspended sediment, inadvertent ingestion of seawater and external irradiation from the handling of fishing gear are not included, since the resulting doses are much smaller than doses from the pathways listed above. These are presented in Reference [20].

The initial assessment of doses to members of the public are calculated by multiplying DPUR values by the maximum annual liquid discharges, as per the following formula: = × ℎ (7.6-1)The DPUR values for coastal discharge scenario are derived from Appendix E of Reference [4]. The key assumptions in the calculation of the DPUR values are that 50% of the fish and all other marine foods are caught from local compartment which is modeled as a “theoretical box” along the coast, and the minimum volumetric exchange rate for most large estuaries and coastal areas is set as 100 m3/s.

When DPUR values are not available for some of the radionuclides discharged from UK HPR1000 in Reference [3], the relevant surrogate radionuclide is considered (cf. Sub-chapter 7.6.2.2).

b) Gaseous discharges

In the IRA methodology, the local resident family is identified as the most exposed group for gaseous discharges at ground-level. The relevant exposure pathways are:

1) Inhalation of radionuclides in the effluent plume;

2) External irradiation from radionuclides in the effluent plume and deposited on the ground; and

3) Internal exposure through consumption of terrestrial food incorporating radionuclides deposited on the ground with conservative habits.

Inhalation of resuspended deposited activity was not included, as it is not usually significant where there is on-going exposure to the effluent plume itself, These are

UK HPR1000 GDA



Rev: 001-1 Page: 15 / 209


also presented in Reference [20].

The initial assessment of doses to members of the public is calculated by multiplying DPUR values by the maximum annual gaseous discharges, as per Equation (7.6-1).

The DPUR values for gaseous discharge scenario are derived from Appendix D of Reference [4]. The key assumptions in the calculation of DPUR values are the following ones:

• The release is at ground level;

• The local resident is assumed to be located at a distance of 100 m from the release point;

• The food consumed is 100% produced at a distance of 500 m from the release point.

When DPUR values are not available for some of radionuclides discharged from UK HPR1000 in Reference [3], the relevant surrogate radionuclide is considered (cf. Sub-chapter 7.6.2.2).

7.6.2.2 Input Data

The main parameters used in IRA methodology are the DPUR values and maximum annual discharges. The detailed information is presented as follows:

a) Maximum annual liquid and gaseous discharges

The maximum annual discharges are presented in T-7B-2 and T-7B-3 for liquid and gaseous discharges respectively. The detailed information on the maximum annual discharges (i.e. the methodology, inputs, assumptions to calculate these and the calculation results) is summarised in the PCER Chapter 6 and detailed in Reference [21] and [22]. The discharges from waste incineration are not considered since onsite waste incineration technology is not adopted for the UK HPR 1000.

b) Input data for liquid discharges

DPUR values of external irradiation and seafood consumption are used for the radiological impact assessment for liquid discharges. The main parameters used to derive the DPUR for liquid discharges are summarised in T-2.4-6 and T-2.4-7 of PCER Chapter 2 (taken from Appendix E of Reference [4]).

The habits data (including 97.5th food consumption rates, generic occupancy time on beach and time spend on handing fishing equipment) combined with the relatively conservative marine environment parameters are used to derive DPUR values, which are considered conservative enough for assessment of dose to the most exposed members of the public due to liquid discharges.

For radionuclides for which there is no available DPUR values, Reference [3], while some surrogate radionuclides are recommended in Table 11 of Reference [3], their use

UK HPR1000 GDA



Rev: 001-1 Page: 16 / 209


would unnecessarily overestimate the dose to members of the public. Instead, the radionuclides that have a similar or higher dose conversion factors are deemed to be more appropriate surrogate radionuclides. On that basis, Cs-137 is selected as the surrogate radionuclides for all the radionuclides for which no DPUR value is available, as it has similar or higher dose conversion factors for most of these radionuclides. This therefore provides an appropriate level of conservatism, and is in line with what is generally used for “Other beta/gamma” emitters by other permit holders in the UK nuclear industry.

c) Input data for gaseous discharges

DPUR values of terrestrial food consumption, external irradiation and inhalation are used for the radiological assessment from gaseous discharges. The main parameters used to derive the DPUR for gaseous discharges to the resident family are summarised in T-2.4-2, T-2.4-3 and T-2.4-4 of PCER Chapter 2 (taken from Appendix D of Reference [4]):

The habits data (including 97.5th food consumption rates and the conservative meteorological conditions with 50% D distribution stability category) is used to derive the DPUR values. This is considered to be conservative enough for the assessment of dose to the most exposed members of the public from gaseous discharges.

For radionuclides for which there is no available DPUR values, Reference [3], while some surrogate radionuclides are recommended in Table 11 of Reference [3], their use would unnecessarily overestimate the dose to members of the public. Instead, Kr-88 is selected as the surrogates for noble gases as it has the highest DPUR value for noble gases, 5.10E-12 μSv/y per Bq/y, and provides an appropriate level of conservatism, Reference [23]. For other radionuclides, Cs-137 is used as the surrogate radionuclide for the same reasons as for the liquid discharges.

7.6.2.3 Results and Discussion

The IRA stage 1 assessment for liquid, gaseous discharges together with the direct dose is summarised in T-7.6-1.

T-7.6-1 Doses to the Most Exposed Members of Public for Stage 1 Assessment

Discharge Route Estimated Dose

(µSv/y) Liquid 27.8

Gaseous 140.0

Direct Dose* 6.3

TOTAL 174.1

* This direct dose is calculated for adult, which is the most exposed person for direct radiation.

The total dose due to liquid discharges, gaseous discharges and direct radiation is

UK HPR1000 GDA



Rev: 001-1 Page: 17 / 209


found to be 174.1 µSv/y, which is dominated by gaseous discharges. It exceeds the 20 µSv/y. Therefore, there is a requirement to conduct a stage 2 assessment.

The detailed information for the dose, from liquid and gaseous discharges, is as follows:

a) The dose to the fisherman family due to liquid discharges is presented in T-7A-1. The total dose from all radionuclides is 27.8 µSv/y, with C-14 being the most significant contributor (97.7%). This is attributed to the much higher liquid discharge rates for C-14 compared to other radionuclides.

b) The dose to the resident family due to gaseous discharges is presented in T-7A-2. The total dose is 140.0 µSv/y, with C-14 being the most significant contributor (82.1%). Similarly, this is attributed to the much higher gaseous discharge rates for C-14 compared to other radionuclides.


7.6.3.1 Methodology


The methodology of stage 2 radiological impact assessment for liquid discharges uses the DPUR values plus a scaling factor derived by refined input data is considered for the dose assessment. The formula used for dose calculation is the following one: ( 2) = ( 1) × (7.6-2)The scaling factor is expressed as the ratio of the two volumetric exchange rates within the stage 1 and stage 2 radiological assessments, which is calculated as follow:

= ℎ ( 1)ℎ ( 2) (7.6-3)b) Gaseous discharges

The methodology of stage 2 radiological impact assessment for gaseous discharges uses the DPUR value plus scaling factors for different pathways. The formula for dose calculation for gaseous discharges is as follow: (Stage 2, ℎ ) = (Stage 1, ℎ ) ×

(7.6-4)

According to Figure 2 of Reference [3], two scaling factors for gaseous discharges are identified, with consideration of an effective release height. One scaling factor is applied to the inhalation and external radiation exposure pathways while another scaling factor is applied to the food consumption exposure pathways. Separate scaling

UK HPR1000 GDA



Rev: 001-1 Page: 18 / 209


factors are used for these pathways because the location of exposure of the local resident for inhalation and external radiation is assumed to be closer to the release point than the location where the food is sourced.

7.6.3.2 Input Data

a) Maximum annual discharges

The maximum annual discharges for stage 2 assessment are the same as those used in the stage 1 assessment, They are provided in T-7B-2 and T-7B-3.

b) Input data for Liquid discharges

The DPUR values for liquid discharges have been introduced in Sub-chapter 7.6.2.2. And the scaling factor used to estimate the dose to the fisherman family are based on the refined volumetric exchange rate of 130 m3/s, which is taken from the minimum volumetric exchange rate from potential sites identified in T-2.4-6 of PCER Chapter 2. This dataset is used as it is more representative of the dispersion at other potential sites.

According to Equation (7.6-3) and the volumetric exchange rates used in stage 1 and stage 2 assessment which are 100 m3/s and 130 m3/s respectively, the scaling factor is calculated as 0.77 for liquid discharges.


The DPUR values for gaseous discharges are provided in Sub-chapter 7.6.2.2. The scaling factors are selected according to the effective stack height used in stage 2 assessment and the scaling factor curves in Figure 2 of Reference [3].

The effective stack height is closely related to the real stack height. The real stack height is dependent upon the local site topography and meteorological conditions, but the site specific information is not available in GDA stage. A real stack height of 70 m, which is Hua-long Pressurised Reactor under construction at Fangchenggang nuclear power plant unit 3 (HPR1000 (FCG3)) stack height value, is considered for the dose assessment in GDA stage. The effective stack height, which is derived using the one third rule for real stack height, Reference [24], is 20 m. Building effects such as re-entrainment is ignored when calculating the activity concentration in air with such a stack height, and a smaller release height is used to model the realistic release process.

According to Figure 2 of Reference [3], the two scaling factors are determined to be:

1) The scaling factor for food ingestion due to the effective stack height of 20 m is 0. 33;

2) The scaling factor for inhalation and external with an effective stack height of 20 m is 0.04.

UK HPR1000 GDA



Rev: 001-1 Page: 19 / 209



The IRA stage 2 assessment for liquid and gaseous discharges together with the direct dose are summarised in T-7.6-2.

T-7.6-2 Doses to the Most Exposed Group for Stage 2 Assessment

Discharge Route Estimated Dose

(µSv/y) Liquid 21.4

Gaseous 22.3

Direct Dose* 6.3

TOTAL 50.0

* This direct dose is calculated for adult, which is the most exposed person for direct radiation.

The total dose due to liquid discharges, gaseous discharges and direct radiation is found to be 50.0 µSv/y, which is dominated by the liquid discharges. It exceeds the 20 µSv/y. Therefore, it is a necessary to conduct a stage 3 assessment.

The detailed information for the doses, from liquid and gaseous discharges, as follow:

a) The dose to the fisherman family due to liquid discharges is presented in the T-7A-3. The total dose is 21.4 µSv/y, with C-14 being the most significant contributor (97.7%) to the dose from liquid discharges. This is attributed to the much higher liquid discharge rates for C-14 compared to other radionuclides.

b) The dose to the resident family due to gaseous discharges is presented in the T-7A-4. The total dose is 22.3 µSv/y, with C-14 being the most significant contributor (93.2%) to the dose of gaseous discharges. Similarity, this is attributed to the much higher liquid discharge rates for C-14 compared to other radionuclide.

The dose results calculated by using refined input data are more realistic compared to the stage 1 radiological impact assessment. However some input data used in this stage 2 assessment are still too conservative. A more detailed radiological impact assessment is needed in the stage 3 assessment.


7.6.4.1 Methodology

As described in the Sub-chapter 7.6.1.2, PC-CREAM 08 is more appropriate for a realistic radiological impact assessment to members of the public.


The radiological impact assessment due to liquid discharges is divided in two steps:

UK HPR1000 GDA



Rev: 001-1 Page: 20 / 209


1) The DORIS module of PC-CREAM 08 is set to predict the activity concentrations in sea water, sediments and marine biotas;

2) The results of the DORIS module are called up in the marine individual dose module of ASSESSOR, used for individual dose calculation. These include the external dose from radioactivity deposited on sediment on the beach and fishing equipment, and the internal dose from inhalation of re-suspended activity (sea spray) and ingestion of seafood.

Different age groups are considered in the radiological assessment: 1 year old infants, 10 year old children, and adults.

Doses to the foetus (including embryo and breast fed infants in the first 3 months after birth) may need to be assessed, particularly if P-32, P-33, Ca-45 and Sr-89 are present in the discharges, Reference [16]. For UK HPR1000, Sr-89 is anticipated to be present in liquid discharges. However, Sr-89 activity level discharged forms a small (if not negligible) part of the liquid discharges, as shown in T-7B-2, and contribute very little to the total dose for the adult group, as shown in T-7A-3. Therefore, doses to the foetus are not considered in this assessment. This will be reconsidered as relevant in the site specific stage.

For other age groups, the dose assessment is conducted with average and high food consumption rates for fisherman family.


The radiological assessment due to gaseous discharges is also divided in two steps:

1) The modules of PLUME, GRANIS, FARMLAND and RESUS are used for predicting the transfer of radionuclides through the environment and providing estimates of the activity concentrations in various environmental media following a continuous release. Each of these modules is used in different scenarios in Reference [5], such as:

The PLUME module is set to calculate the activity concentrations in air, deposition rates and external gamma dose rates from radionuclides in the plume (plume gamma) at various distances downwind of the release point;

The GRANIS module is set to model the transfer of radionuclides through the soil and takes into account the shielding properties of the soil when estimating doses one metre above the soil surface;

The FARMLAND module is set to predict the transfer of radionuclides into terrestrial foods following deposition onto the ground;

The RESUS module is set to estimate the activity concentrations in air arising from the resuspension of previously deposited radionuclides;

UK HPR1000 GDA



Rev: 001-1 Page: 21 / 209


2) The results of these modules are called up in the atmospheric individual module of ASSESSOR used for individual dose calculation. These include the external dose from plume and ground, and the internal dose from inhalation of plume, resuspension of radioactive substances and ingestion of terrestrial foods.

Different age groups are considered for the gaseous radiological impact assessment, which are similar with those used in the dose assessment for liquid discharges.

Similarly to liquid discharges, Sr-89 is anticipated to be present in gaseous discharges from the UK HPR1000. However, Sr-89 activity level in gaseous discharges forms a small (if not negligible) part of the gaseous discharges, as shown in T-7B-3, and contributes very little to the total dose for the adult group, as shown in T-7A-2. Therefore, doses to the foetus are not considered in this assessment. This will be reconsidered as relevant in the site specific stage.

For other age groups, the dose assessment for resident family is conducted with average and top two food consumption rates.

7.6.4.2 Input Data

a) Maximum annual discharges

The maximum annual discharges for stage 3 assessment are the same as those used in the stage 1 and stage 2 assessments. They are provided in T-7B-2 and T-7B-3.

b) Input data for liquid discharges

Refined environmental parameters used for the stage 3 radiological impact assessments for liquid discharges include:

1) Environmental parameters

The marine environmental parameters used to model the dispersion of liquid discharges are presented T-2.4-6 of PCER Chapter 2. This dataset is used as it represents the conservative dispersion conditions for all potential sites for UK HPR 1000.

2) Habits data

Refined habits data used for stage 3 liquid radiological impact assessment is provided in T-2.4-8and T-2.4-9 of PCER Chapter 2.

3) Transfer parameters through the marine environment

Radionuclides are transferred from seawater to the marine organisms and sediments, these processes are defined by distribution coefficients for the marine sediment and the concentration factors. Default values in PC-CREAM 08 are used for these two parameters, which are mainly adopted from International Atomic Energy Agency (IAEA) No 247 in Reference [25].

UK HPR1000 GDA



Rev: 001-1 Page: 22 / 209


For Br, Mo and Rb, there are no default values provided in PC-CREAM 08. The minimum distribution coefficient and the maximum concentration factor of the radionuclides discharged from UK HPR1000 are used for these three radionuclides groups. These parameters are presented in T-7B-4.

This ensures the radioactivity concentration in food is not underestimated and therefore the total dose is not underestimated as the ingestion pathway is the main contributor to the total dose.


1) Dispersion and deposition parameters

Refined meteorological conditions are considered and presented in T-2.4-2 of PCER Chapter 2. The 65% D condition represents the condition for coastal location of Great Britain as shown in Figure 11 of Reference [26]. The Hosker-Smith scheme of meteorological conditions is recommended, Reference [5], as it is quantitative and takes into account a number of factors including the effect of ground roughness, wind speed over a wide range and the sensible heat flux in the lower levels of the atmosphere. Other important dispersion and deposition parameters considered are as follow:

• The surface roughness value used for defining agricultural areas is 0.3m, which is used to calculate the wind speed at the effective stack height and the vertical standard deviation of the plume for the various stability categories.

• The effective stack height of 20 m used for the stage 3 radiological assessments is similar to that used in the stage 2 radiological assessment.

• The deposition rates are mainly depended on the dry deposition velocity and washout coefficient. The default values in PC-CREAM 08 are used and presented in T-7B-5.

2) Transfer parameters through the terrestrial environment

Radionuclides are transferred from soil to the plants. This process is defined by the equilibrium soil-to-plant concentration ratios (wet weight plant: dry weight soil). The default values in PC-CREAM 08 are used except for Na as there is no default value for it in PC-CREAM 08. The values are taken from Table D.10 and Table D.11 of Reference [4]. And the transfer parameters for all radionuclides are presented in T-7B-6.

Radionuclides are transferred from pasture to animal products. This process is defined by the equilibrium transfer factors and the biological half-lives. The default values in PC-CREAM 08 are used except for Na. The values are taken from Table D.8 and Table D.9 of Reference [4] and are summarised in T-7B-7.

3) Habits data

UK HPR1000 GDA



Rev: 001-1 Page: 23 / 209


The local resident family is assumed to be located at a distance of 100 m from the discharge point, and foodstuffs are produced at a distance of 500 m from the discharge point, which is consistent with stage 1 and stage 2 radiological impact assessments.

Refined habits data, used for the stage 3 gaseous radiological impact assessment, are provided in T-2.4-3 and T-2.4-4 of PCER Chapter 2. The main assumptions include the food consumption rates considered at “top two” rates and the consumption of terrestrial food assumed as 100% locally produced.

4) Other input data

The external dose from deposited activity to a local resident is mainly from activity deposited on the ground surface. The undisturbed wet soil is selected for calculating external dose from deposited activity as the activity concentration on surface ground of undisturbed wet soil is higher than that in surface ground of well mixed soil.


The predicted activity concentrations in atmosphere at the receptor locations (located at 100m from release point) calculated by PLUME Module of PC-CREAM 08 are presented in T-7.6-3.

The dose results include the following two scenarios:

a) Most exposed scenario: The results present the doses from liquid and gaseous discharge routes at high/top two consumption rates combined with direct doses.

b) Average scenario: The results present the doses from liquid and gaseous discharge routes at average consumption rates combined with direct doses.

The doses for above scenarios are presented in T-7.6-4 and T-7.6-5.

T-7.6-3 Activity Concentrations in Atmosphere at 100m from Release Point

Radionuclides Activity

concentration in air (Bq/m3)


concentration in air(Bq/m3)

Ag-110m 1.58E-08 Tc-99 (Mo-99) 3.38E-21 Ar-41 4.95E-05 Na-24 3.41E-09

Ba-137m 1.30E-10 Nb-95 1.88E-11 Ba-139 5.49E-11 Ni-63 8.25E-08 Ba-140 4.70E-11 Rb-86 1.17E-10

La-140 (Ba-140) 7.48E-15 Rb-88 2.00E-09 Br-82 2.32E-08 Sb-122 1.13E-09 Br-83 1.56E-07 Sb-124 3.20E-09

Kr-83m (Br-83) 5.48E-10 Sr-89 1.13E-10 Br-84 6.84E-08 Sr-90 4.83E-11 C-14 8.50E-02 Y-90 (Sr-90) 4.84E-15

UK HPR1000 GDA



Rev: 001-1 Page: 24 / 209






Co-58 8.28E-08 Sr-91 4.56E-12 Co-60 1.02E-07 Y-91m (Sr-91) 3.52E-14 Cr-51 4.72E-08 Y-91 (Sr-91) 2.09E-17

Cs-134 8.44E-08 Sr-92 7.78E-13 Cs-136 4.42E-09 Y-92 (Sr-92) 1.41E-15 Cs-137 9.73E-08 Tc-99m 2.59E-10

Ba-137m (Cs-137) 1.33E-08 Tc-99 (Tc-99m) 8.90E-22 Cs-138 1.37E-09 Te-125m 3.96E-11 Fe-59 6.11E-09 Te-127 1.35E-11 H-3 2.64E-01 Te-129 1.26E-11

I-129 2.94E-11 I-129 (Te-129) 5.89E-25 I-130 2.95E-08 Te-129m 7.33E-10

I-131 4.31E-06 Te-129 (Te-129m) 4.03E-12

Xe-131m (I-131) 9.68E-11 I-129 (Te-129m) 3.42E-23 I-132 9.87E-07 Te-131m 7.36E-11

I-132m 4.47E-09 I-131 (Te-131m) 2.44E-15

I-132 (I-132m) 1.24E-11 Te-131 (Te-131m) 1.12E-12

I-133 2.59E-06 Te-132 1.81E-10 Xe-133 (I-133) 1.33E-10 I-132 (Te-132) 5.03E-13

Xe-133m (I-133) 3.17E-10 Te-133m 8.90E-11

I-134 5.48E-07 I-133 (Te-133m) 2.74E-14

I-135 2.40E-06 Te-133 (Te-133m) 2.71E-12

Xe-135 (I-135) 1.70E-09 Te-134 2.01E-11 Xe-135m (I-135) 5.97E-08 I-134 (Te-134) 1.46E-13

Kr-83m 2.56E-06 Xe-131m 3.90E-05 Kr-85 1.35E-02 Xe-133 5.86E-01

Kr-85m 1.18E-05 Xe-133m 9.11E-03

Kr-85 (Kr-85m) 8.10E-13 Xe-133 (Xe-133m) 4.65E-07

Kr-87 6.10E-06 Xe-135 1.74E-01

Rb-87 (Kr-87) 9.53E-23 Cs-135 (Xe-135) 5.52E-14

Kr-88 1.91E-05 Xe-138 1.25E-03

Rb-88 (Kr-88) 4.06E-07 Cs-138 (Xe-138) 1.50E-05

La-140 2.39E-12 Zr-95 3.38E-11 Mn-54 2.58E-08 Nb-95 (Zr-95) 2.57E-16

UK HPR1000 GDA



Rev: 001-1 Page: 25 / 209






Mo-99 9.81E-10 Nb-95m (Zr-95) 2.50E-15 Tc-99m (Mo-99) 1.05E-12 ---

T-7.6-4 Summary Doses of High/Top Two Consumption Rates and Direct Exposure

Discharge Route Adult Annual

Dose μSv/y Child Annual

Dose μSv/y Infant Annual

Dose μSv/y

Liquid discharges*

11.2 4.3 0.9

Gaseous discharges**

9.8 9.6 15.1

Direct radiation

6.3 3.2 2.2

Total 27.3 17.1 18.2 * Doses are calculated with high consumption rates of marine foodstuffs, and data source from T-7A-5 to T-7A-7; ** Doses are calculated with “top two” consumption rates of terrestrial foodstuffs, and data source from T-7A-11 to T-7A-13.

T-7.6-5 Summary Doses of Average Consumption Rate and Direct Exposure

Discharge route Adult annual Dose μSv/y

Child Annual Dose μSv/y

Infant Annual Dose μSv/y

Liquid discharges* 2.2 3.0 0.6

Gaseous discharges** 6.9 6.4 7.7

Direct radiation 6.3 3.2 2.2

Total 15.4 12.6 10.5

* Doses are calculated with average consumption rates of marine foodstuff, and data source from T-7A-8 to T-7A-10;

** Doses are calculated with average consumption rates of terrestrial foodstuffs, and data source from T-7A-14 to T-7A-16.

The dose due to gaseous discharges is higher than that due to liquid discharges and direct radiation. The highest total predicted dose is found to be 27.3 µSv/y.

UK HPR1000 GDA



Rev: 001-1 Page: 26 / 209


The detailed information of the results is presented hereafter:


The detailed dose to an adult, child and infant of a fisherman family with high and average consumption rates of marine foodstuffs are presented in T-7A-5 to T-7A-10.

The doses to an adult, child and infant of a fisherman family with high consumption rates from liquid discharges are 11.2 µSv/y, 4.3 µSv/y and 0.9 µSv/y, respectively. The dose to an adult is higher than that to a child and infant.

By comparing the dose results for each pathway, it is found that the dominant pathway is ingestion of seafood which contributes 99.1%, 99.9% and 98.8% of the total dose for the adult, child and infant respectively. C-14 has the most significant contribution to the total dose, estimated at 98.8%, 99.4% and 98.4% of the total dose for the adult, child and infant, respectively.

The doses to an adult, child and infant of a fisherman family with an average consumption rate from liquid discharges are 2.2 µSv/y, 3.0 µSv/y and 0.6 µSv/y, respectively.

The dose is also dominated by ingestion of seafood which contributes to 95.8%, 98.2% and 98.4% of the total dose for the adult, child and infant, respectively. C-14 also has the most significant contribution to the total dose, with 96.8%, 99.5% and 97.9% of the total dose for the adult, child and infant, respectively.


The detailed doses to adult, child and infant of a resident family with “top two” and average terrestrial food consumption rates are presented in T-7A-11 to T-7A-16.

The doses to an adult, child and infant of a resident family with “top two” consumption rates from gaseous discharges are 9.8 µSv/y, 9.6 µSv/y and 15.1 µSv/y, respectively. The dose to an infant is higher than that to a child and an adult.

By comparing the dose results from each pathway, it is found that the dominant pathway is ingestion of terrestrial foods which contributes to 84.0%, 84.9% and 92.3% of the total dose for the adult, child and infant, respectively. C-14 has the most significant contribution to the total dose, estimated at 96.0%, 96.3% and 95.7% of the total dose for adult, child and infant, respectively.

The doses to an adult, child and infant of a resident family with average consumption rates for gaseous discharges are 6.9 µSv/y, 6.4 µSv/y and 7.7 µSv/y, respectively.

The dose is also dominated by ingestion of terrestrial foods which contribute to 77.4%, 77.2% and 84.9% to the total dose for the adult, child and infant, respectively. C-14 also has the most significant contribution to the total dose, estimated at 95.7%, 96.1% and 95.6% of the total dose for the adult, child and infant, respectively.

UK HPR1000 GDA



Rev: 001-1 Page: 27 / 209


7.7 Annual Dose to the Representative Person The definition of the representative person is “an individual receiving a dose that is representative of the more highly exposed individuals in the population” in Reference [12]. The ICRP and the PHE have stated that this term is the equivalent of and replacement for the average member of the critical group.

ICRP Publication 103 in Reference [12] states that “the representative person may be hypothetical, but it is important that the habits…used to characterise the representative person are typical habits of a small number of individuals representative of those most highly exposed and not the extreme habits of a single member of the population. Consideration may be given to some extreme or unusual habits, but they should not dictate the characteristics of the representative person considered”.

The detailed information on definition of the candidates of the representative person is presented in Sub-chapter 7.7.1, and the dose results to all candidates of the representative person are presented in Sub-chapter 7.7.3.

7.7.1 Methodology

The radiological assessment for the representative person is based on the information from the stage 3 radiological impact assessment and the direct radiation from sources on site. The candidates of the representative person are determined by the methodology presented in the F-7.7-1 and described below:

a) Case A resident family: The most exposed individual of the resident family to gaseous discharges is identified, and the most exposed person to gaseous discharges is also considered to be exposed to a lower degree to liquid discharges (only the pathway of consuming seafood at average rate is considered) and direct radiation.

b) Case B fisherman family: The most exposed individual of fisherman family to liquid discharges is identified, and the most exposed person to liquid discharges is also considered to be exposed to a lesser degree to gaseous discharges (only the pathway of consuming terrestrial food at average rate is considered) and direct radiation.

c) Case C: The most exposed individual to direct radiation is identified, and the most exposed person to direct radiation is also considered to be exposed to a lesser degree to gaseous discharges (only the pathway of consuming terrestrial food at average rate is considered) and liquid discharges (only the pathway of consuming seafood at average rate is considered).

The candidate among the three above cases with the highest dose is the likely representative person. In GDA stage, the dose from direct radiation is calculated for one conservative exposure scenario as described in Sub-chapter 7.5. It is obvious that

UK HPR1000 GDA



Rev: 001-1 Page: 28 / 209


the dose results of case C is lower than that of case A and case B, therefore this possible candidate is no longer considered in the identification of the representative person.

F-7.7-1 Methodology for Determine Representative Person

7.7.2 Input Data

The input data for the representative radiological impact assessment is the same as that used in the stage 3 assessment, both for liquid and gaseous discharges.

7.7.3 Results and Discussion

The dose results to the two groups of candidates of the representative person are presented inT-7.7-1 and T-7.7-2.

T-7.7-1 Dose to Fisherman Family

Age group

Liquid discharges##

(μSv/y)

Gaseous discharges#

(μSv/y)

Direct dose(μSv/y)

Total

Adult* 11.2 5.3 6.3 22.8 Child** 4.3 4.9 3.2 12.4 Infant*** 0.9 6.5 2.2 9.6

* Data source from T-7A-17;

** Data source from T-7A-18;

*** Data source from T-7A-19.

# Doses from gaseous discharges are taken from the values of ‘Total Dose of Terrestrial Foods (Average Consumption)’ in T-7A-17 to T-7A-19, which are calculated by summing the doses from ingesting Cow liver, Cow meat, Cow milk, Fruit, Green vegetable, Root vegetable, Sheep liver and Sheep meat in T-7A-14 to T-7A-16 respectively;

## Doses from liquid discharges are the result of Grand Total minus Total Dose of Terrestrial

UK HPR1000 GDA



Rev: 001-1 Page: 29 / 209


Foods (Average Consumption) in T-7A-17 to T-7A-19.

T-7.7-2 Dose to Resident Family

Age group

Liquid discharges# (μSv/y)

Gaseous discharges##

(μSv/y)

Direct dose(μSv/y)

Total

Adult* 2.2 9.8 6.3 18.3 Child** 3.0 9.6 3.2 15.8 Infant*** 0.6 15.1 2.2 17.9

* Data source from T-7A-20;

** Data source from T-7A-21;

*** Data source from T-7A-22;

# Doses from liquid discharges are taken from the values of ‘Total Dose of Marine (Average Consumption)’ in T-7A-20 to T-7A-21, which are calculated by summing the doses from ingesting Crustaceans, Fish, Molluscs and Seaweed in T-7A-8 to T-7A-10;

## Dose from gaseous discharges is the result of that Grand Total minus Total Dose of Marine (Average Consumption) in T-7A-20 to T-7A-21.

The dose results from liquid and gaseous discharges are presented in T-7A-17 to T-7A-22, and the direct radiation results are presented in the T-7.5-1.

Based on the results in T-7.7-1 and T-7.7-2, the maximum total dose is received by an adult from the fisherman family (22.8 μSv/y). Therefore the adult of the fisherman family is considered as the representative person.

According to the dose results, the significant pathways are depended on the categories of receptors and age groups:

a) For the fisherman family, the dose to the adult is dominated by exposure to liquid discharges, whilst the doses to the child and infant are dominated by exposure to gaseous discharges.

According to the results of different age groups from fisherman family, the dominant pathway is ingestion of seafood for the adult which contributes to 67.2% of the total dose, and ingestion of terrestrial foodstuffs for the child and infant which represents 53.5% and 88.3% of the total dose, respectively.

C-14 has the most significant contribution to the total dose, with 98.5%, 98.4% and 96.5% of the total dose to the adult, child and infant, respectively.

b) For the resident family, the doses to the adult, child and infant are dominated by exposure to gaseous discharges.

According to the results of different age groups from resident family, the

UK HPR1000 GDA



Rev: 001-1 Page: 30 / 209


dominant pathway is ingestion of terrestrial foodstuffs which contributes to 68.7%, 64.7% and 88.8% of total dose for the adult, child and infant, respectively.

C-14 has the most significant contribution to the total dose, with 96.7%, 97.1% and 95.9% of the total dose to the adult, child and infant, respectively.

7.8 Potential Dose due to the Short-term Discharge During normal operations, elevated short-term releases of radionuclides may occur as a result of planned maintenance operations or particular features of operations of plants, which may lead to a higher annual dose to the members of the public than that assessed for a uniform release rate over the year.

7.8.1 Methodology

a) Discharge scenario

The assessment of the potential dose due to short-term discharges only considers gaseous discharges as the liquid discharges from the UK HPR1000 are made on a batch basis. The design prevents spikes of short-term activity being released due to the effluent being held in storage tanks which are sampled prior to final discharge to the environment. If activity values exceed the prescribed limits, the effluent can be returned to the effluent waste management system for further treatment until levels are acceptable for release into the environment. For this reason, no short-term dose assessment of the liquid effluent discharged to the environment will be undertaken. Therefore only the doses from gaseous discharges are considered for the short-term radiological impact assessment.

b) Dispersion and deposition of radionuclides

The gaseous discharges are estimated by the methodology set out in Reference [27] and [28]. The gaseous dispersion model ADMS 5 is used to calculate the activity concentrations in plume per unit discharge, the deposition rate per unit discharge and the plume gamma doses of the radionuclides from the short-term discharges.

c) Dose calculation

The radiological impact assessment of short-term discharges considers the following exposure pathways:

1) Inhalation and external radiation from plume;

2) Ground external radiation and ingestion of terrestrial foodstuffs for a year following the release.

The doses are calculated using the approach outlined in Appendix I of Reference [28]:

1) Ingestion dose

UK HPR1000 GDA



Rev: 001-1 Page: 31 / 209


, = ∑ ∑ × , , × , × × (7.8-1) Where:

DoseIng,n: Individual effective dose (Sv) to the chosen age group received from the food consumption, over exposure time (t), of all foods (f), for radionuclide (n);

Depn: Total deposition on the ground from the passage of the plume (Bq/m2), calculated by the Equation (7.8-2);

IntActt,f,n: Integrated activity concentration per unit deposit (Bq∙y∙kg per Bq/m2) in food f over time t;

Ingt,f: Ingestion rate (kg/y) of food f over time t for the chosen age group;

DPUIn: Dose per unit intake (Sv/Bq) for the radionuclide and chosen age group, taken from ICRP 72, Reference [29];

LocPcntf: The percentage of food f that is locally produced.

Depn is calculated as: = × × , (7.8-2) Where:

Depn: Total deposition on the ground from the passage of the plume (Bq/m2);

Rn: Release rate of radionuclide n (Bq/s);

Tr: Release duration (s);

Cdep,n: Deposition rate of the radionuclide n per release rate (Bq/(m2∙s) per Bq/s), output of ADMS 5 presented in T-7B-8.

2) Inhalation dose

, = × , × ℎ × × , + , × (7.8-3) Where:

DoseInh,n: Inhalation dose for radionuclide n (Sv);

Actn: Activity concentration in air during the passage of the plume (Bq/m3), calculated by the Equation (7.8-4);

DCinh,n: Dose coefficient to calculate committed effective dose for radionuclide n (Sv/Bq), taken from ICRP 72, Reference [29];

Inh: Breathing rate (m3/h);

Tid,od: Indoor and outdoor plume exposure time (h);

UK HPR1000 GDA



Rev: 001-1 Page: 32 / 209


LFinh,id,od: Indoor inhalation reduction factor for radionuclide n.

Actn is calculated as: = × , (7.8-4) Where:

Actn: Activity concentration in air of radionuclide n during the passage of the plume (Bq/m3);


Cair,n: Activity concentration in air of radionuclide n per unit release rate (Bq/m3 per Bq/s release), output of ADMS 5 presented in T-7B-8.

3) Deposited exposure dose = × × × , × + , × (7.8-5)

Where:

DoseDep: Effective dose (Sv) from deposited radionuclides n over time t;

n: Radioactive decay constant (1/h) for radionuclide n;

T: Deposited exposure time (h);

Depn: Activity concentration on the ground resulting from the deposition of the plume (Bq/m2), calculated by the Equation (7.8-2);

DCext: Deposited dose coefficient (Sv/h per Bq/m2), taken from Reference [30];

LFdep,id,od: Deposited indoors and outdoors location factors;

Fid,od: Fraction of time spent in indoors and outdoors location.

4) Plume gamma dose , , = , × × × , + , × (7.8-6) Where:

Doseplu,n,γ: Individual effective dose due to external gamma exposure from radionuclide n in the plume (Sv);

Doseunit,n: Individual effective dose rate at distances downwind due to external gamma exposure from the plume per unit release rate of radionuclide n (Sv/s per Bq/s), output of ADMS 5 presented in T-7B-8;

UK HPR1000 GDA



Rev: 001-1 Page: 33 / 209



Tid,od: Indoor and outdoor plume exposure time (s);

LFγ,id,od: Indoor and outdoor location factor of plume gamma exposure for radionuclide n.

5) Plume beta dose

, , = , × × , × × , + , × (7.8-7)

Where:

Doseplu,n,β: Individual effective dose due to external beta exposure from radionuclide n in the plume (Sv);

Doseunit,n : Individual effective dose rate due to external beta exposure from the cloud per unit air concentration of radionuclide n (Sv/h per Bq/m3), taken from Table 3.10 of Reference [5];


Cair,n: Activity concentration in air of radionuclide n per unit release rate (Bq/m3 per Bq/s release), output of ADMS 5 presented in T-7B-8;

Tid,od: Indoor and outdoor plume exposure time (h);

LFβ,id,od: Indoor and outdoor location factor of plume beta exposure for radionuclide n.

7.8.2 Input Data

a) Short-term discharges

Operational (i.e. routine, planned or reasonably foreseeable) short-term discharges can be higher than normal releases for a number of reasons, including variations in site production. For the UK HPR1000, the maximum monthly discharges presented as short-term discharges are shown in T-7B-9.

Not all of the radionuclides in the short-term discharges are important to the dose to members of the public. The significant radionuclides are identified according to the dose results from continuous discharges of gases in T-7B-10. The radionuclides which have higher dose contribution to the total dose are selected in the short–term radiological assessment. These radionuclides are listed in T-7B-11. It is also conservatively assumed that these radionuclides are released uniformly over a short period of 24 hours.

b) Exposure time for each pathway

UK HPR1000 GDA



Rev: 001-1 Page: 34 / 209


For external radiation (including gamma dose and beta dose) and inhalation of radionuclides from plume pathways, the exposure time is consistent with the release time as the radionuclides are not considered to be accumulated in air after release. It is cautiously assumed that individuals stay outside during the entire passage of the plume, so the outdoor exposure time for external radiation and inhalation of radionuclides from plume is set at 24 hours, and the indoor exposure time from inhalation of radionuclides and external radiation from plume is set at 0 hours.

For ground external radiation and ingestion of terrestrial foodstuffs pathways, the exposure time is considered for the first year following the short-term release as it is highly unlikely that the same exposed groups will be affected over a number of years as described in the general guidance of Reference [27].

c) Dispersion and deposition parameters

1) Dispersion parameters

The effective stack height for short-term discharges is set at 20 m, similar to that assumed in the stage 2 and stage 3 dose assessments.

The default values of stack diameter (1m) and temperature of gases (15°C) in ADMS 5 are used, and the discharge velocity is set as 10 m/s for reasonable conservatism as it is lower than that in the HPR1000 (FCG3).

The meteorological conditions are presented in T-2.4-2 of PCER Chapter 2, which is the realistic cautious conditions recommended in Reference [28]. It is assumed that the meteorological conditions are represented by atmospheric stability category D and other relevant parameters. ADMS 5 uses the surface heat fluxes instead of atmospheric stability categories to represent the meteorological conditions. The relationship between stability categories and the surface heat fluxes is shown in Figure 2 of NRPB R91, Reference [26]: the 0 W/m2 of surface heat flux corresponds to category D meteorological conditions.

The wind is assumed to blow directly toward members of the public with a degree of lateral spread. The lateral spread is related to the release time, according to the approach in Reference [26]. The lateral spread of the wind direction for the 24 hours release can be presented as follows:

• The dispersion of the plume in the horizontal plane is the result of turbulence processes together with fluctuations in wind direction. The standard deviation σ in the horizontal plane is presented as: σ = σ + σ (7.8-8) Where: σ : Turbulent diffusion component (m);

UK HPR1000 GDA



Rev: 001-1 Page: 35 / 209


σ : Component due to fluctuations in wind direction (m). The σ for the downwind distance of 100m and under the Pasquill category D, which is identified in Figure 10 of Reference [26], is determined as 8 m.

The σ is calculated using the following equation: σ = 0.065 (7.8-9)

Where: u: Wind speed, m/s; T: Release duration in hour, h;

: Downwind distance, m.

The σ for the downwind distance of 100 m calculated from Equation (7.8-9) is 48.6 m.

The value of σ at 100m is 49.3m. • The lateral spread is 27.6 degree, which is calculated as follows: = 2 ( . ) (7.8-10) 2) Deposition parameters

The deposition process is mainly defined by the parameters of the dry deposition velocity and washout coefficient.

• Dry deposition velocity

For particles discharged from UK HPR1000, the dry deposition velocities are calculated by using the default parameters within the internal model of ADMS 5, and the method used for calculating the deposition velocity is presented as follows:

The deposition velocity Vd contains a diffusive part (Vd’) and gravitational settling part (a terminal velocity Vs), which can be presented as = ( / ) (7.8-11) Vd’ and Vs are not known for particles. Vd’ can be calculated by the internal model of ADMS 5 with default values including particle diameter (1μm) and particle density (1000 kg/m3).

Vs are estimated from the properties of the particles by the ADMS 5.

For noble gases, the dry deposition velocities are 0 m/s as they are not considered to

UK HPR1000 GDA



Rev: 001-1 Page: 36 / 209


be deposited on the ground.

For H-3, the dry deposition velocity is considered to be 0.004 m/s, as recommended in NRPB W54, Reference [28].

For C-14, it is assumed to be returned to the atmosphere in a timescale that is short compared to its half-life, therefore, no allowance is made for dry deposition.

For other radionuclides discharged from UK HPR1000, the default values in ADMS 5 are used.

Based on above information, the dry deposition velocities of radionuclides are presented in T-7B-12.

• Washout coefficient

For noble gases, the washout coefficients are not considered as they are not deposited on the ground.

For C-14, it is assumed to be returned to the atmosphere in a timescale that is short compared to its half-life, therefore, no allowance is made for washout.

For other radionuclides discharged from UK HPR1000, the washout coefficients are calculated from Equation (7.8-12) with rainfall rates of 0.1 mm/h. Washout coefficients of radionuclides are presented in T-7B-12.

= (7.8-12) Where: Λ: Washout coefficient (1/s); A: Default value in ADMS 5, set as 0.0001;

B: Default value in ADMS 5, set as 0.64.

d) Habits data

It is assumed that members of the public are located at 100 m from the discharge point and all food is produced at 500 m from the discharge point. For the purpose of a conservative dose assessment, all the foodstuffs ingested by members of the public are produced locally.

The habits data used for the short-term dose assessment is provided in T-2.4-3 and T-2.4-4 of PCER Chapter 2. The terrestrial foodstuffs are assumed to be consumed at the “top two” rates, and the breathing rates are different from those used in the assessment of continuous discharges, be

General Nuclear System Ltd....PC CREAM 08, Health Protection Agency, HPA-RPD-58,November 2009. [6]...

Documents

Transcript of General Nuclear System Ltd....PC CREAM 08, Health Protection Agency, HPA-RPD-58,November 2009. [6]...