IAEA International Atomic Energy Agency
Assessments and control of exposures to public and biota for planned releases
to the environment
IAEA MODARIA II (2016–2019)
30th Oct 2017
Juan C. Mora
IAEA
Problem to be addressed
• The paradigm “the standards of environmental control needed to protect the general public would ensure that other species were not put at risk” changed to “the need to be able to demonstrate (rather than to assume) that the environment is being protected against radionuclides”.
• “Establish a consistent and comprehensive basis for the proper protection of people and the environment against radiation risks […] without unduly limiting the operation of facilities.”
IAEA
USA - Washington DC (US-Nuclear Regulatory Commission Headquarters)
(15-18 May 2017)
1st INTERIM MEETING
IAEA
- People attending – 23 (13 from USA) - Countries - 9 - 22 presentations - 3 technical visits (NRC, NIST, Calvert Cliff NPP)
General information
IAEA
WG3: Working steps (Chapters) 1. Identify practical international and national guidance for the demonstration of the compliance with
requirements for the protection of the environment against ionizing radiations (Stephanie Bush-Goddard).
2. Identify state of the art tools, sources of data and methods for performing dose assessments in routine radioactive discharges which can be used in integrated assessments of the humans and the biota, including uncertainties (Justin Smith).
3. Study, Validate and Incorporate H3 and C14 state of the art models (Volodymyr Korolevych + Nana Kwamena)
4. Identify a set of cases and scenarios where explicit assessment of the environment would be necessary (Iuri Bonchuk + Kapil Deo Singh).
5. Carry out dose assessments for humans and the biota in those scenarios with associated uncertainty analysis (Anca Melintescu + Dan Galeriu).
6. Reduce the number of surrogate species which are used in dedicated dose assessment in terms of reverse modelling. Considerations on endangered species (Benoit Charrasse + Amanda Andersson)
7. Communication with stakeholders (Cecile Boyer + Elisabeth Leclerc)
8. Evaluate and compare models, approaches, parameters and other characteristics used in the assessments (Benjamin Zorko + JC Mora).
9. Discuss the results and give advice to the IAEA on needs and gaps (JC Mora).
IAEA
WG3: What has been done Dose assessments for humans
Dose assessments for biota
Atmospheric discharges
Source term details Annual (Average or pdf) discharge of each radionuclide Bq y-1
Annual discharge of each radionuclide Bq y-1 Or Averaged or pdfs concentrations measured in each environmental compartment (air and soil).
Model type Gaussian plume model
Key model inputs Release height, distance from release, roughness length, deposition velocity, met data based on D Pasquill stability category and wind speed.
Model configuration (eg calculation domain) Uniform distribution calculated in the centre
of the gaussian plume. Model valid up to 80 km from the installation.
Model outputs (please provide details of endpoints and what they represent eg mean, maximum,
percentile – at a single distance or averaged over an area/volume) Deterministic or stochastic pdfs obtained based on pdf defined for each input data or parameter along the model For each sector and distance: Activity concentration in air at ground level (Bq m-3) Total deposition rate (Bq m-2 s-1) Dose rate (external and internal) (Sv y-1)
Links with other models and their outputs (eg foodchain model)
Concentration in soils for humans is partly calculated from atmospheric deposition. Foodchain (terrestrial vegetables and animals) concentrations are obtained from concentration in soils (calculated from atmospheric deposition and water irrigation).
Dose assessments for humans
Dose assessments for biota
Lake discharges
Source term details
Annual discharge of each radionuclide Bq y-1
Annual discharge of each radionuclide Bq y-1 Or Averaged or pdfs concentrations measured in each environmental compartment (water and sediments).
Model type Box model (original equations dynamic, but into the code only equilibrium conditions are considered)
Key model inputs Flow rate of the income river. Flow rate of the discharge. Depth of the lake. Total average volume of the lake. Load of suspended sediments Kd Bioaccumulation factors (animals and vegetables)
Model configuration (eg calculation domain) Homogeneous and instantaneous mix along the complete volume of the lake. No spatial resolution, although the dynamic model can easily be implemented.
Model outputs (please provide details of endpoints and what they represent eg mean, maximum,
percentile – at a single distance or averaged over an area/volume) Water and sediments concentrations (deterministic and probabilistic)
Links with other models and their outputs (eg river model, foodchain model)
Concentration in soils for humans is partly calculated from water irrigation. Foodchain (terrestrial vegetables and animals) concentrations are obtained from concentration in soils (calculated from atmospheric deposition and water irrigation). Foodchain (aquatic vegetables and animals) concentrations are calculated using the unfiltered concentrations in the water.
IAEA
WG3: What has been done
IAEA
WG3: What has been done
IAEA
WG3: What has been done
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WG3: What has been done
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WG3: What has been done
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WG3: During this week
• Discussions/Advance on the different chapters
• First draft of most of them
IAEA
WG3: During this week
• Joint meeting WG3/WG5 (validation of atmospheric releases)
• Joint meeting WG1/WG3/WG7 (sharing experience)
• Joint meeting WG1/WG7 (marine models)
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Introductory training courses
• Introduction and Examples CROM • RESRAD offsite • Guided Interactive Statistical Decision Tool - • MOPER (Joint meeting WP3/WP7)
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WG3 – Tritium and C-14 sub-group
• Derive and validate simple models for short, prolonged and chronic releases • Investigate the relative importance of different processes
within a complex model (intra-model analysis)
• Test simplified model performance against real climatic data (model-measurement comparison)
• Benchmark simple models against research grade models (model-model comparison)
• Investigate unresolved issues with organically-bound tritium (OBT) observed in field samples from some locations
