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					EMRAS II – Working Group 1
Reference Methodologies for
Controlled Discharges


Justin Smith




                          Centre for Radiation, Chemical and Environmental Hazards
                                                         Radiation Protection Division
                                  formerly the National Radiological Protection Board
                 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

        Radiation Protection Division of the Health Protection Agency
                   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.
   – < 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.

         Radiation Protection Division of the Health Protection Agency
                  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)

         Radiation Protection Division of the Health Protection Agency
                 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



        Radiation Protection Division of the Health Protection Agency
                        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


       Radiation Protection Division of the Health Protection Agency
                  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


       Radiation Protection Division of the Health Protection Agency
• Atmospheric       Typical applications
   –  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

         Radiation Protection Division of the Health Protection Agency
                    Typical applications
                                                                  Habit data,
                                                                Population and
                                                            Agricultural production
                                       Dose Coefficients
                                                                 distributions




                                                        Doses
    Source of             Transfer in               to people and
  Radionuclides         in Environment               populations



                        Exposure pathways


Discharge to
                      Pasture            Cow           Milk          Human
atmosphere

         Radiation Protection Division of the Health Protection Agency
                   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)




        Radiation Protection Division of the Health Protection Agency
                  System structure


                          Database

User input                                           Results


                             GUI


 Fortran                                            Input
  DLLs                                            summary


    Radiation Protection Division of the Health Protection Agency
                               Models
                       Models                                       Datasets


Plume       Farmland          Granis             Resus
                                                                 Cloud beta
                                                                 Ground beta




                      Assessor – atmospheric
                     individual and collective



        Radiation Protection Division of the Health Protection Agency
                                 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…)

          Radiation Protection Division of the Health Protection Agency
                             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



      Radiation Protection Division of the Health Protection Agency
                              Models
• Rivers – Screening dilution model or dynamic
  compartmental model: activity concentrations in
  fish, water and sediments


        River screening                        River dynamic



                          Assessor – river
                          individual only



       Radiation Protection Division of the Health Protection Agency
          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.




         Radiation Protection Division of the Health Protection Agency
          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.

         Radiation Protection Division of the Health Protection Agency
        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.




       Radiation Protection Division of the Health Protection Agency
        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.




       Radiation Protection Division of the Health Protection Agency
                      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

         Radiation Protection Division of the Health Protection Agency
                     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)

          Radiation Protection Division of the Health Protection Agency
                       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




       Radiation Protection Division of the Health Protection Agency
                           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



       Radiation Protection Division of the Health Protection Agency

				
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