Modelling and Data for Radiological Impact Assessments ... Documents/2nd...Identification of...

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


The proposal

Objective

Development of guidance on uncertainty analysis for dose

assessment in routine releases,

including interpretation of results


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).


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.


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.


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…).


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?


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)



SU_MMC


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


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]


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)


Role of measurement uncertainties

• Uncertainties and variabilities

• Interpretation of environmental monitoring results

• Statistics limitations

• Surveys in populations


Correlations


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


Communication issues

How should the dose assessments be communicated:

• Operator Regulator

• Comunication to the public, involvement of

stakeholders

• Risk comunication


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


The Forge

Thank you!

MODARIA. WG 5 – Uncertainty and variability analysis for assessments of radiological

impacts arising from routine discharges of radionuclides

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