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EMRAS II

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... representative person in due course so in state of transition. ... Training courses planned. Oct 27-28 2009. provisionally Mar 2-3, Jun 29-30 and Oct 26-27 2010 ... – PowerPoint PPT presentation

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Title: EMRAS II


1
EMRAS II Working Group 1 Reference
Methodologies for Controlled Discharges
  • Justin Smith

2
Response to questions
  • 1 )Nuclear context what types of facilities does
    your methodology cover?
  • Almost any type of facility where discharges
    occur to atmosphere, sea (European waters) or
    rivers and can be considered as continuous and
    constant.
  • 2) National Organisation who is the authority in
    your country? What types of manufactures do you
    have? Who are the experts?
  • Environment Agency, SEPA.
  • Nuclear industry activities, NORM activities,
    radiopharmaceuticals.
  • Advice on Radiation Protection from HPA, EA,
    SEPA, FSA and NDAWG

3
Response to questions
  • 3) Do you use critical group concept? Or the new
    ICRP version of it?
  • We consider them to be the same in practice and
    we believe ICRP description is equivalent.
    However, because critical group terminology is
    still used in UK legislation we are still using
    it. We will move to representative person in due
    course so in state of transition.
  • 4) What are the regulatory limit values? Are
    they doses? Are they concentrations? Or other
    units?
  • Annual dose limit 1mSv from all sources, annual
    dose constraint 0.3 mSv for a single source,
    annual site constraint 0.5 mSv for a number of
    operations on a single site.
  • lt 20 uSv annual ( 1 e6 per year) is EA (Cm 2919
    white paper) threshold of optimisation ie if BPM
    no further reduction need be sought.
  • Operator will seek an authorisation (under RSA
    93) from EA or SEPA and discharge limits will be
    set on the basis that the practice has been
    optimised and no dose constraints or limits
    exceeded.

4
Response to questions
  • 5) What modelling approaches do you use?
  • Equilibrium models, compartmental models (marine,
    river, terrestrial food), Gaussian plume model
    (finite and semi-infinite cloud gamma models),
    empirical models for external exposure and
    resuspension.
  • Designed for continuous and constant discharges.
  • 5a) Do you transfer coefficients? (if so which
    ones?).
  • Yes.
  • Terrestrial activity concentration ratios between
    soil and plant, and between feed and meat, liver
    and milk.
  • For river and marine environments activity
    concentration ratios between filtered water and
    sediments and biota.
  • Sources include IAEA (Safety Series No 19, 2001
    and TRS 364), NCRP (Screening models for releases
    of radionuclides to atmosphere, surface water,
    and ground. NCRP Report No 123I , 1996) and
    Coughtrey (Radionuclide distribution and
    transport in terrestrial and aquatic ecosystems.
    A compendium of data. 1985)

5
Response to questions
  • 5b) What type of atmospheric modelling do you
    use?
  • Gaussian plume model.
  • (Investigating use of NAME III)
  • 5c) Do you use site specific data?
  • Yes, but depends on the type and extent of the
    assessment eg for a large study looking at many
    sites generic habit data may be used.
  • Other issues Collective dose, short term planned
    releases

6
PC-CREAM 08
  • CEC report Methodology for evaluating the
    radiological consequences of radioactive
    effluents release in normal operations (1979)
  • EC report Methodology for assessing the
    radiological consequences of routine releases of
    radionuclides to the environment (1995)
    PC-CREAM 98
  • New methodology PC-CREAM 08

7
Typical applications
  • Prospective assessments
  • discharges from a single site at a constant
    annual release rate
  • for comparison of annual dose in e.g. 50th year,
    with dose limit and constraint
  • Retrospective assessments
  • past or current doses from a single site if
    discharges can be approximated to a constant
    annual release rate
  • Calculation of collective doses for comparative
    purposes

8
Typical applications
  • Atmospheric
  • Inhalation of plume
  • External gamma and beta from cloud
  • External gamma and beta from ground
  • Inhalation of resuspended material
  • Ingestion of cow meat, cow liver, cow milk, sheep
    meat, sheep liver, green vegetables, root
    vegetables, fruit and grain
  • Marine
  • Inhalation of seaspray
  • External gamma and beta from sediments
  • External gamma and beta from fishing gear
  • Ingestion of seaweed, fish, molluscs and
    crustaceans
  • River
  • External gamma and beta from sediments
  • Ingestion of fish and drinking water
  • Not available for collective dose assessments

9
Typical applications
Habit data, Population and Agricultural
production distributions
Dose Coefficients
Doses to people and populations
Source of Radionuclides
Transfer in in Environment
Exposure pathways
Discharge to atmosphere
Pasture
Cow
Milk
Human
10
Typical applications
  • PC CREAM uses effective dose
  • as defined in ICRP Publication 60
  • dose coefficients from ICRP Publication 72
  • committed to age 70
  • 3 age groups
  • 1 year old infants
  • 10 year old children
  • Adults
  • (For fetus advice given in Methodology report)

11
System structure
Database
User input
Results
GUI
Input summary
Fortran DLLs
12
Models
Models
Datasets
Plume
Cloud beta Ground beta
Farmland
Granis
Resus
Assessor atmospheric individual and collective
13
Models
  • Plume Gaussian plume model (R91) activity
    concentrations in air, deposition rates and cloud
    gamma dose rates for specified release rate.
  • Farmland Compartmental model for soil,
    vegetation and animals activity concentrations
    in foods per unit deposition rate.
  • Granis Compartmental model for soil and gamma
    dose from infinite plane time integrated ground
    gamma dose per unit deposition rate over one
    year.
  • Resus Garland model for resuspension time
    integrated activity concentration in air per unit
    deposition rate over one year.
  • Datasets Cloud beta dose rates per unit air
    concentration (DOE/EH-0070) and ground beta dose
    rates per unit deposition (Holford 1989
    Supplement)

14
Models
  • Doris Compartmental model for north European
    waters and Mediterranean Sea activity
    concentrations in marine foods, water and
    sediments

Doris
Assessor marine individual and collective
15
Models
  • Rivers Screening dilution model or dynamic
    compartmental model activity concentrations in
    fish, water and sediments

River screening
River dynamic
Assessor river individual only
16
Improvements and new features
  • Implementation of an extensive database to hold
    all data related to the dose assessment
    calculation.
  • Development of an improved graphical user
    interface.
  • The database includes an increased number of
    default sites
  • A comprehensive list of radionuclides.
  • Better treatment of progeny radionuclides.

17
Improvements and new features
  • PLUME deposition of progeny which have a
    different deposition velocity to that of the
    parent change the meteorological parameters run
    for several stack heights at once.
  • GRANIS It is easier to define the materials that
    comprise each soil layer and these can be stored
    for later use.
  • RESUS includes contribution to the resuspended
    activity concentration in air from the first day
    after the initial deposition.
  • FARMLAND includes review of model parameters
    and a revised fruit model.

18
Improvements and new features
  • Dynamic river model revised to include transfer
    from filtered water to bed sediment. Includes
    default data describing some major European
    rivers. Review of water treatment values, Kd and
    CF values
  • DORIS revised following the MARINA II study
    (EC, 2003) increases the extent of the region
    modelled better represents the remobilisation
    process.

19
Improvements and new features
  • ASSESSOR, has been updated to make it easier to
    select the model results that will be used in the
    assessment and to provide greater flexibility
    when defining the habits of individuals.
    Radionuclide and pathway breakdowns are provided
    for all dose estimates including marine
    collective doses.

20
Progeny in models
  • In general the first radioactive progeny not in
    secular equilibrium (SE) on the timescales of
    interest is modelled although some parts of the
    system model the full radioactive decay chain.
  • Plume - first progeny not in SE over 3 minutes
  • Farmland first progeny not in SE over 1 year
  • Granis full chain
  • Resus first progeny not in SE over 1 year
  • Doris full chain
  • Rivers no progeny

21
Progeny in Assessor
  • Aquatic external exposures
  • Fishing gear uses mean gamma and beta energies
    which take account of progeny in SE
  • Ground shine from sediments uses mean gamma
    energies and beta dose coefficients which take
    account of progeny in SE
  • Atmospheric external exposures
  • Cloud shine uses binned gamma energies and beta
    dose coefficients for individual nuclides
    (exception where d notation is used)
  • Ground shine binned gamma energies for
    individual nuclides dose coefficients for
    deposited beta which include progeny
  • Inhalation dose coefficients include progeny,
    (progeny in SE in seaspray ignored)
  • Ingestion dose coefficients include progeny,
    (progeny in SE in food ignored)

22
Current status
  • Current version of PC-CREAM 08 (1.0.1.2/1.0.2) is
    complete
  • Updated version of methodology report (RP 72) to
    be published
  • Dedicated website under development
  • Training courses planned
  • Oct 27-28 2009
  • provisionally Mar 2-3, Jun 29-30 and Oct 26-27
    2010

23
The future
  • Future development to the system may include
  • Ability to use output from other atmospheric
    dispersion models
  • Inclusion of collective dose calculations for
    discharges to rivers
  • Inclusion of a sewers model
  • Revised population and agricultural production
    grids
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