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Modelling and Data for Radiological Impact Assessments
“MODARIA”
WG 5 – Uncertainty and variability analysis for assessments of
radiological impacts arising from routine discharges of
radionuclides.
WG Leader: Juan Carlos Mora
IAEA Scientific Secretary: Diego Telleria
Vienna. November,11th – 15th, 2013
MODARIA. WG 5 – Routine Discharges
Brief
TSO, Regulators and Industry
Vienna 2012 – 22 Participants (16 countries)
- 13 presentations
Madrid 2013 – 20 Participants (13 countries)
- 12 presentations (2 code courses)
Vienna 2013
MODARIA. WG 5 – Routine Discharges
The proposal
Objective
Development of guidance on uncertainty analysis for dose
assessment in routine releases,
including interpretation of results
MODARIA. WG 5 – Routine Discharges
The proposal
Tasks
(1) Identify possible tools and methods for uncertainty and
variability analysis applicable to dose assessments methods
and codes for routine radioactive discharges.
(2) Identify cases and scenarios where information on
uncertainty and variability of parameters is available for the
testing of methodologies.
(a) Definition of realistic scenario for a hypothetical NPP
based on information from INPRO or EMRAS II projects.
(b) Definition of a realistic scenario based in French NPP
(Chinon).
MODARIA. WG 5 – Routine Discharges
The proposal
Tasks
(3) Discuss the realism of the models and scenarios applied.
(4) Discuss the sources of uncertainty and available methods
which allow their quantification.
(5) Elaborate methods and procedure for performing a priori
sensitivity analysis to identify key parameters in the used
models.
MODARIA. WG 5 – Routine Discharges
The proposal
Tasks
(6) Discuss the distributions of parameters and data to be used
in the different scenarios and codes.
(7) Identify correlation factors among different parameters used
in the models.
(8) Explain the role of environmental monitoring data in
uncertainty analysis processes.
MODARIA. WG 5 – Routine Discharges
The proposal
Tasks
(9) Carry out exercises with the different codes in the scenarios
defined.
(a) Sensitivity analysis to be carried out in each of the
exercises.
(b) Discuss the different methods used in the evaluations
carried out, focusing on the choice of parameters probability
distribution functions (pdfs) and correlations among them.
(10) Discuss the communication of results of calculations
which include uncertainty analysis to the different
stakeholders (regulators, public…).
MODARIA. WG 5 – Routine Discharges
Methodology for the assessment
• What are the steps for a dose assessment, and how they are
affected by the purpose of the assessment?
• When should uncertainties be included?
• When is enough a qualitative discussion?
• When is necessary a quantitative determination?
• When should variabilities be included?
• Should some data be fixed in advance?
MODARIA. WG 5 – Routine Discharges
Identification of tools
6 codes which include uncertainties analysis
and were prepared for routine discharges were identified:
CROM, IMPACT, CRYSTAL BALL, SU_MMC, SYMBIOSE, (MCMC)
Brief overview was provided for 4 of them in Madrid
(2 freely distributed to the group)
MODARIA. WG 5 – Routine Discharges
Identification of tools
SU_MMC
MODARIA. WG 5 – Routine Discharges
Identification of tools
MODARIA. WG 5 – Routine Discharges
Identification of tools
MODARIA. WG 5 – Routine Discharges
Identification of tools
MODARIA. WG 5 – Routine Discharges
Identification of scenarios
Radionuclides GBq y-1 3H 54200 14C 16.5
54Mn 0.01 60Co 0.072 58Co 0.057
110mAg 0.158 123mTe 0.009 124Sb 0.010 125Sb 0.028
131I 0.011 134Cs 0.010 137Cs 0.011
Table 1.- Chinon NPP annual liquid releases - year 2011
MODARIA. WG 5 – Routine Discharges
Identification of scenarios
Radionuclide Q, Bq·a-1 Radionuclide Q, Bq·a-1 Radionuclide Q, Bq·a-1
H-3 3.44E+13 Kr-88 4.07E+11 Xe-135m 1.48E+11
C-14 (CO2) 2.70E+11 Sr-89 5.92E+06 Xe-138 1.11E+11
Ar-41 1.26E+12 Sr-90 2.33E+06 I-131 1.37E+09
Cr-51 3.59E+06 Zr-95 3.70E+05 I-132 5.92E+09
Mn-54 2.11E+06 Nb-95 1.55E+06 I-133 4.07E+09
Fe-59 1.04E+06 Ru-103 6.29E+05 I-134 9.62E+09
Co-57 3.03E+05 Ru-106 2.89E+04 I-135 7.40E+09
Co-58 1.78E+07 Sb-125 2.26E+04 Cs-134 1.78E+06
Co-60 4.07E+06 Xe-131m 2.11E+13 Cs-136 1.22E+06
Kr-85 1.81E+14 Xe-133 3.00E+13 Cs-137 3.33E+06
Kr-85m 2.22E+11 Xe-133m 3.70E+11 Ba-140 1.55E+05
Kr-87 1.48E+11 Xe-135 1.59E+12 Ce-141 4.81E+05
Table 1.- Annual discharges of radionuclides Q from an APR 1400 NPP, as used for estimating annual
dose via the atmospheric pathway for the INPRO ENV project
Parameter Symbol Unit Fixed
value
Parameters for
triangular
distribution
Low Base High
time period that crops are
exposed to contamination
during the growing season
forage grasses te(1) d
30
food crops te(2) 60
delay (hold-up) time that
represents the time interval
between harvest and
consumption of the food
forage th(1)
d
0
stored feed for
animals th(2) 90
leafy vegetables
th(3)
0 1 7
root crops 0 14 28
non-leafy
vegetables 0 14 28
average time between
collection and human
consumption
milk tm d 0 1 7
meat tf d 7 20 30
average dry matter content
leafy vegetables 0.076
root crops 0.143
non-leafy
vegetables 0.135
fraction of the year that animals consume fresh
pasture vegetation fp 0.7
amount of feed (dry matter)
consumed by the animal
milk cow Qm kg·d–1 16
meat cow Qf kg·d–1 12
Table 5.- Values for crop and soil exposure periods, delay times, and
other vegetable parameters [3], [9]
MODARIA. WG 5 – Routine Discharges
Identification of parameters and distributions
Element Distribution Min GM Max
Ag Log normal
truncated
1.6x104
8.5x104
4.5x105
Am Log normal
truncated
3.8x103
1.2x105
3.9x106
Ba Log normal
truncated
1.5x102
2.0x103
2.6x104
Be Log normal
truncated
3.2x103
4.2x104
5.4x105
Ce Log normal
truncated
2.8x104
2.2x105
1.7x106
Cm Log uniform 10 7.0x10
4
Co Log normal
truncated
3.0x103
4.4x104
6.3x105
Cs Log normal
truncated 830
2.9x104
1.0x106
Table 2.- Kd in the abiotic freshwater modules (L.kg-1 dry weight)
Element Distribution Min GM Max
Ac Log uniform 450 5.4x1
03
Ag Log uniform 36 1.5x1
04
Am Log normal
truncated 70 2600
9.7x1
04
As Log uniform 25 3.0x1
03
Be Log uniform 240 3.0x1
03
Bi Log uniform 120 1.5x1
03
Br Log uniform 15 180
Ca Log normal
truncated 0.69 8 92
Ce Log normal
truncated 46 1200
3.1x1
04
Cm Log normal
truncated 644 9300
1.3x1
05
Table 3.- Soil Kd in the agricultural modules (L.kg-1 dry weight)
MODARIA. WG 5 – Routine Discharges
Role of measurement uncertainties
• Uncertainties and variabilities
• Interpretation of environmental monitoring results
• Statistics limitations
• Surveys in populations
MODARIA. WG 5 – Routine Discharges
Correlations
MODARIA. WG 5 – Routine Discharges
A priori sensitivity analysis
• Use of fixed percentage variations
• Use of predefined pdfs
• All or some parameters
• Identification of more sensitive parameters
• Reduction of total uncertainty by improving the knowledge of
more sensitive parameters
MODARIA. WG 5 – Routine Discharges
Communication issues
How should the dose assessments be communicated:
• Operator Regulator
• Comunication to the public, involvement of
stakeholders
• Risk comunication
MODARIA. WG 5 – Routine Discharges
Products
“MODARIA WG5: Towards a practical
guidance for the performance of uncertainty
calculations in the assessment of routine
releases.”
Authors: Juan Carlos Mora, Diego Tellería, Adriana Curti, Christophe
Mourlon, Iurii Bonchuk, Fabiene Vermorel , Laura Marang,
Sohan Chouhan, Benjamin Zorko, Juraj Duran, Ahmed
Alneaimi, Anna Maria Blixt Buhr, Pavol Chylý, Goran Ivanis,
Charlotte Lager, Beatriz Robles, Ann-Christin Hägg, Maria
Elizabete Figueiredo, Cíntia Melazo Dias, Jarmila Bohunova,
Fabricio Fiengo Perez, Mikhail Iosjpe, Pawel M. Krajewski,
Jige Shen, Andrew Woodruffe
MODARIA. WG 5 – Routine Discharges
The Forge
Thank you!
MODARIA. WG 5 – Uncertainty and variability analysis for assessments of radiological
impacts arising from routine discharges of radionuclides