Research and development of

environmental tritium modelling,

an update

D. Galeriu and A. Melintescu

“Horia Hulubei” National Institute of Physics and

Nuclear Engineering, Bucharest – Magurele, Romania

2012 HPS Annual Meeting

Sacramento, CA

THE INCREASED INTEREST FOR

TRITIUM • Greenpeace actions in Canada, UK, Romania, Japan

• Groundwater tritium near nuclear reactors (USA, Canada)

• The need to preserve public trust in nuclear energy AFTER FUKUSHIMA

• EU Scientific Seminar “Emerging Issues on Tritium and Low Energy Beta Emitters” (Luxemburg, 13 November 2007)

• Canadian Nuclear Safety Commission: Tritium Studies Project (2007-2010) → Environmental Fate of Tritium in Soil and Vegetation

• Autorite de Surete Nucleaire (France) → Livre Blanc TRITIUM (2008-2010)

• International Atomic Energy Agency- EMRAS program, Phase I and II - Environmental Modelling for Radiation Safety

• EMRAS I – WG 2 - Modelling of Tritium and Carbon-14 transfer to biota and man working group - Final report on web

• EMRAS II WG 7 – "Tritium" Accidents - TECDOC in preparation

Tritium Human Dosimetry

a Metabolic Approach

• Actual (ICRP) tritium dosimetry is contested (CERRIE, Greenpeace, IEER);

• AGIR report recommends an RBE=2 (HTO) and leaves the problem of retention open;

• Parameter uncertainty of ICRP model was analyzed before (Harrison 2002);

• A NEW MODEL APPROACH WAS PUBLISHED including the age, gender and race effect;

• Variability, as well as RBE uncertainty;

• RBE for OBT (Chen J., 2006. Radiation quality of tritium. Radiat. Prot. Dosim. 122:546–8)

• Approach based on energy metabolism and probabilistic assessment;

• Galeriu D., Melintescu A., 2010. Retention of tritium in reference persons: a metabolic model. Derivation of parameters and application of the model to the general public and to workers

J. Radiol. Prot. 30:445–468

RBC

brain

viscera

muscle

adipose

remainder

B

L

O

O

D

P

L

A

S

M

A

WB Water

Stomach

content

Small intestine

content

Fbpl_rbc

Frbc_bpl

Fbpl_br

Fbr_bpl

Fbpl_vis

Fvis_bpl

Fbpl_mus

Fmus_bpl

Fbpl_ad

Fad_bpl

Fbpl_rem

Frem_bpl

Fsmi_bpl

Fsmi-wbw

Fst_smi

Fsmi_lgi

Fwbw_out Fwbw_bpl

Fbpl_wbw

Intake OBT

Intake HTO

Fbpl_uo

Excretion of OBT in urine

Our model flowchart

ROLE OF BRAIN

energy fraction basal

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

NB 1 5 10 15f 15m af amage, gender

muscle

brain

adipose

remaider

Viscera

Glucose utilization (metabolic rate)

for cortex region at various human ages

0

2

4

6

8

10

12

0 1 2 3 4 5 6 7 8 9 10

BMR model

BM

R e

xp

Reconstruction of basal metabolic rate

• Various brain regions show a

similar pattern;

• ADULT AND 1 YEAR OLD CHILD

USE A SIMILAR ENERGY FOR

BRAIN FUNCTIONING (per kg);

• Training for survival uses more

energy to establish the base of

knowledge and prompt reactions

to environment challenge;

• At small scale, similar for many

mammals

TESTS with human experimental data

NO other model was tested with OBT experimental data on humans

HTO intake OBT intake

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

0 50 100 150 200 250 300 350

Time (d)

OB

T c

oncentr

ation (

Bq/L

) OBT_exp

OBT_model

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

0 50 100 150 200 250 300 350

Time (d)

OB

T c

oncentr

ation (

Bq/L

) OBT_conc_exp

OBT_conc_mod

LT301 OBT in urine

0.001

0.01

0.1

1

10

0 20 40 60 80 100 120 140

Day

perc

en

t o

f in

take

exp

model

OBT in urine

0.001

0.01

0.1

1

10

0 50 100 150

Time (d)

Pe

rce

nt

of

inta

ke

exp

model

Predicted doses for a single OBT intake (10 -11 Sv Bq-1)

using different RBE values

age ICRP H (uniform, RBE=1) E (non-uniform, RBE=1) E (non-uniform, RBE>1)

5% 50% 95% 5% 50% 95% 5% 50% 95%

3 months 12 26.4 28.9 31.4 19.4 21.4 23.5 61.6 69.5 77.4

1 year 12 16.6 18.1 19.7 12.4 13.8 15.2 38.7 43.8 48.6

5 years 7.3 9.5 10.5 11.5 7.7 8.6 9.7 23.7 26.8 29.7

10 years 5.7 8 8.7 9.5 5.7 6.2 7.0 17.3 19.5 21.7

15years 4.2 6.4 7 7.6 5.8 5.4 6.2 14.5 17.1 19.2

adult 4.2 6.7 7.2 7.7 4.4 4.9 5.2 13.9 15.6 17.4

H - uniform distribution, no wT; E – non uniform distribution to be compared with ICRP

Moderate increase, but infant a factor 2

Total T and OBT in urine after HTO or OBT

intake

Dynamics of OBT in blood plasma and red blood

cells OBT after an OBT intake of 1000 Bq Use bioassay

SATISFIES THE RECENT REQUIREMENTS

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

0.1 1 10 100 1000

time (d)

Co

nc. (B

q/k

g d

m)

O_bloodpl(OBT)

O_RBC(OBT)

0.0001

0.001

0.01

0.1

1

10

-1 19 39 59 79 99

time (d)

% e

xc

rete

d p

er

da

y

totT_HTO

totT_OBT

OBT_HTO

OBT_OBT

Transfer of tritium in the environment

after accidental releases from nuclear facilities Report of Working Group 7

Tritium Accidents

of EMRAS II Topical Heading

Approaches for Assessing Emergency Situations

Environmental Modelling for

Radiation Safety (EMRAS II) Programme

• Developing a standard conceptual dynamic model for tritium dose assessment for

acute releases to the atmosphere and water bodies, starting with the external input for

tritium dynamics in atmosphere or water from the source to receptor.

• Agreement on common sub-models for the specific transfers or processes, based on

an interdisciplinary approach involving the understanding of the processes and key

parameters, based on the recent research in Life Sciences. Quality assurance requires a

moderate conservatism.

• Defining the framework for an operational model (requirements for meteorological data,

atmospheric transport, site specific data).

• Achieve the capability to assimilate real measured data in the models.

WG leader D. Galeriu, IAEA TECDOC in preparation

CONTENTS

1. Introduction (P. Cortes, D. Galeriu, V. Berkovskyy)

2. Key mechanisms for tritium transfer in terrestrial environment (P. Guetat)

3. Interaction matrices and associated processes for terrestrial pathways of tritium transfer (S. Le Dizes-Maurel)

4. Tritium atmospheric washout (L. Patryl, D. Galeriu, A. Melintescu)

5. HT and HTO dry deposition and reemission (M. Ota, H. Nagai)

6. HTO uptake in plants and the OBT formation during the day time (A. Melintescu, D. Galeriu)

7. Overview experiments on tritium transfer from air to plants and the subsequent conversion to OBT (D. Galeriu, A. Melintescu, S. Strack, S.B. Kim, M. Andoh-Atarashi)

8. Review on soil-plant tritium transfer (V. Korolevych)

9. Tritium transfer in wheat experiments and models tests (D. Galeriu, L. Patryl, S. Strack, A. Melintescu, M. Ota)

10. Tritium transfer in farm animals (D. Galeriu, A. Melintescu)

11. Briefing of complex model (H. Nagai, M. Ota)

12. Tritium in aquatic foodchain (A. Melintescu, D. Galeriu, F. Siclet, F. Lamego)

13. Quality assurance of data (S.B. Kim)

14. Quality assurance of model (D. Galeriu, J. Duran)

15. Status and perspectives of accidental tritium modelling (D. Galeriu)

WG-7 TRITIUM ATMOSPHERIC

WASHOUT

Average and standard deviation washout rate for the

Marshall-Palmer, Willis and Log normal distributions

computed using Kessler, Seinfield, Andronache,

Loosmore and Chamberlain drop velocity equations

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1972 1982 1992 2002 2012

year

wash

ou

t ra

te

On site tritium studies at Cernavoda NPP - 2011

Application of ISCPRIME

A ev stk (Bq)/d

0

2E+11

4E+11

6E+11

8E+11

1E+12

1.2E+12

1.4E+12

1.6E+12

18-Nov-10 7-Jan-11 26-Feb-11 17-Apr-11 6-Jun-11 26-Jul-11 14-Sep-11 3-Nov-11 23-Dec-11 11-Feb-12

date

Bq

/d

A ev stk(Bq/d)

0.00E+00

1.00E+11

2.00E+11

3.00E+11

4.00E+11

5.00E+11

6.00E+11

7.00E+11

1/1/11 2/15/11 4/1/11 5/16/11 6/30/11 8/14/11 9/28/11 11/12/11 12/27/11

Daily Tritium atmospheric emission U1 (top) and U2

(bottom)

-1000 -800 -600 -400 -200 0 200 400 600 800 1000

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

0.000

1.000

2.500

3.000

4.000

5.000

6.000

7.000

8.000

8.000

X ( m)

Y (

m)

Average tritium concentration in air (Bq/m3) – 2011 using

ISC-PRIME and local meteorology

-1000 -800 -600 -400 -200 0 200 400 600 800 1000

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

0.000

200.0

400.0

600.0

800.0

1000

1500

2000

2000

X ( m)

Y (

m)

Average tritium in precipitation (Bq/L) – 2011, using

ISC-PRIME and local meteorology

station

ADI-

02

ADI-

04

ADI-

05

ADI-

06

ADI-

08

ADI

-09

ADI-

10

ADI-

11

ADI-

12

ADI-

13

distance km 11 10 1.6 1.2 2.5 9 12 0.62 0.34 0.62

bearing 80 135 168 220 315 15 215 50 83 315

Measured

2011average 0.24 0.21 0.48 0.25 0.29 0.13 0.06 0.49 3.67 2.04

Model

Average 0.09 0.25 2.05 3.05 0.45 0.55 0.21 0.95 0.97 2.35

P/O 0.37 1.18 4.23 12.27 1.57 4.24 3.53 1.92 0.26 1.15

station ADI-12 SSS-18 ADI-13 ADI-05 ADI-08

distance 0.34 0.43 0.62 1.6 2.5

bearing 75 210 315 170 315

Measured 2011

average 207 172 268 131 25

Model average 84.05 570.31 112.29 195.34 24.80

P/O 0.40 3.32 0.42 1.49 0.98

Measurements and Model - air concentration (up),

precipitation concentration (down)

Follow-up Monthly values have larger ranges for

predicted/observed ratios, explained by:

• PRIME simplicity

• Site complexity

• Quality and number of meteorological instrumentation

• Influence of small hills and Danube valley

• Modelling of tritium washout near buildings

• Need of local rain drop size distribution

Acknowledgements: radiation protection staff at CNE

Peter Eckhoff, U.S. Environmental Protection Agency

Updated AQUATRIT – AQUAtic TRITium

Model • Dynamic model for predicting 3H transfer in aquatic food

chain;

• More coherent assessments for the aquatic food chain, including the benthic flora and fauna;

• Explicit application for the Danube ecosystem;

• Model extension to the specific case of dissolved organic tritium (DOT)

• Model tests with data for large trout (S.B. Kim, AECL)

• Full details given in:

A. Melintescu, D. Galeriu, 2011. Dynamic model for tritium transfer in an aquatic foodchain. Radiat. Environ. Biophys. 50:459–473

A. Melintescu, D. Galeriu, S.B. Kim, 2011. Tritium dynamics in large fish – a model test. Radioprotection, 46(6):S431-S436

The dynamics of OBT concentration in different aquatic

organisms, considering a tritium release in Danube of 3.7

PBq on August 1 and a river flow of 6000 m3s-1

0.001

0.01

0.1

1

10

100

1000

0.1 1 10 100 1000

time (d)

OB

T c

oncentr

atio

n (

Bq/k

g fm

)

phytoplankton zooplankton zoobenthos

benthic algae molluscs carp

pike roach

• Cardiff case – it should be noted that the tritated waste from GE Healthcare (former

Amersham) includes not only the HTO and the by-product, but also the high bio available

tritiated organic molecules (i.e. hydrocarbons, amino acids, proteins, nucleotides, fatty

acids, lipids, and purine / pyrimidines).

• For the model application - the input data: the annual average of total tritium and organic

tritium releases from GE Healthcare, tritium concentration in sea water and the monitoring

data for mussel and flounder have been taken from literature

• Using the available input data - the model successfully predicts the trend for tritium

concentration in mussels and flounders

DOT- The Cardiff case

1000

10000

100000

1000000

0 2000 4000 6000 8000 10000 12000

time (day)

Tri

tiu

m c

on

cen

trati

on

(B

q/k

g f

m)

mussel (model)

flounder (model)

mussel (exp)

flounder (exp)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

0 20 40 60 80 100 120 140 160

time (days)

OB

T c

on

c.

(Bq

/L)

model OBT conc. (Bq/L)

exp. OBT conc. (Bq/L)

Large trout (S.B. Kim, AECL)

Comparison between model results and

exp. data for OBT concentration in fish in

the case of OBT uptake

0

5000

10000

15000

20000

25000

30000

0 20 40 60 80 100 120 140 160

time (days)

OB

T c

on

c.

(Bq

/L)

normal growth

slow growth

fasting

Dependence of OBT concentration dynamics

on various feeding regimes for the same final

mass

• Feeding regime - important factor;

- In the experimental conditions - individual variability in food intake and growth;

Further improvements in the experimental methodology must take into account

the fish tagging.

Review of dynamic models for dose

assessment of non-human biota –

analysis of questionnaire

• Interest in recent years regarding dynamic models for protection of non-human biota

• Current assessment models mainly CF-based

• Potential case for dynamic-based models for non-equilibrium scenarios – Pulsed discharges

– Decommissioning situations

– Accidents

• Modelling group agreed to look at the current state of the art on dynamic modelling: – Look at what models are around

– Assess the need and demand for the dynamic models

– Release chapter for the final Tecdoc

Jordi Vives i Batlle EMRAS II 3rd Technical Meeting, Vienna, 24 – 28 January 2011

Identification of fields of interest for the IAEA EMRAS II

follow-up programme: Assess impact to humans and

biota in an integrated approach

OUR VISION: Complex dynamic model for H-3 and C-14 transfer in mammals

using Energy Metabolism (variant of Metabolic Theory in Ecology)

A. Melintescu, D. Galeriu, 2010. Radiat. Environ. Biophys. 49:657–672

D. Galeriu, A. Melintescu, N.A. Beresford, H. Takeda, N.M.J. Crout, 2009. Radiat. Environ.

Biophys. 48:29–45

BP

Vis

Mus

Ad

Rem

FBPVis

FVisBP

FBPMus

FMusBP

FBPRem

FRemBP

FBPAd

FAdBP

OBT_urine

FBPu

WBW

FBPWBW

sink

FWBWout

FWBWBP

S

SI

exit

FSSI

FSIex

FSIBP

FSIWBW

RBC

FRBCBP

FBPRBC

OBT_milk

FBPm

OBT_input

HTO_input

Preliminary allometric relationships for organs specific

metabolic rates ,2005

Inputs

Body and organ mass (case specific); organ composition (generic)

Specific organ Metabolic Rates (animal specific?, use generic) - key input

Basal Metabolic Rate (BMR) and Field Metabolic Rate (FMR)

Diet and digestion style; Food and water intake

Known for HUMANS

Good knowledge for

FARM ANIMALS &RAT

SMR for wild by allometry

SMR Liver

0.1

1

10

0.01 0.1 1 10 100 1000

mass kg

MJ/(

daykg

)

2005

Wang

Last

SMR liver, various allometry

0.001

0.01

0.1

1

10

0.1 1 10 100 1000

Body mass (kg)

SM

R (

MJ

/(d

kg

))

adipose

muscle

liver

kidney

heart

GIT

brain

skin

skeleton

Model tests with cow data (no

calibration)

• Several exposures

– Single HTO intake

– Continuous HTO intake

– Continuous OBT intake

• Cow mass, feed and water

intake, milk and urine production

taken from experiments

• All other model parameters

taken from literature – no

calibration with tritium data

• Model gives predictions within

a factor 2 of the observed data

100

1000

10000

100000

0 50 100 150

time (d)

milk O

BT

co

ncen

trati

on

BQ

/L

milk_OBT_present

milk_OBT_TRIF

milk_OBT_UFOTRI

milk_OBT_exp

Experimental data and model predictions for

OBT in milk after OBT fed for 26 days.

Experimental data were reported only after stop dosing

Tests with growing pigs and veal

1. Pigs of 8 weeks old fed for 28 days with HTO:

Muscle P/O ~ 1

Viscera P/O ~1

2. Pigs of 8 weeks old fed for 28 days with milk powder contaminated with

OBT:

Muscle P/O ~ 3

Viscera P/O ~ 2

3. Pigs of 8 weeks old fed for 21 days with boiled potatoes contaminated with

OBT:

Muscle P/O ~ 0.2

Viscera P/O ~ 0.3

4. Two calves of 18 and 40 days old, respectively fed for 28 days with milk

powder contaminated with OBT:

Muscle P/O ~ 1

Viscera P/O ~ 2.5

Few experiments

Not quite sure about these values → Potential

explanation: old and insufficiently reported

experimental data

Generalized coordinates:

normalized concentration (same per kg whole body)

non dimensional time (use scaling with average metabolic rate)

266.0073.0Re BWMR

0.001

0.01

0.1

1

0 5 10 15 20 25 30T*RMR

no

rmali

sed

co

ncen

trati

on

lemming

chipmunk

rabbit

red fox

red deer

duck

On average FMR/RMR~3

For specific case 2-5

Generalized coordinates

are useful to avoid

mass difference

Life span must be considered

Lemming - ReMR=0.1543 d-1.

Lifespan ~2 years

Deer - ReMR 0.0211 d-1

Lifespan 10 years

Reference duck included

Only matures considered

Humans to be added.

0.01

0.1

1

10

100

0 20 40 60 80 100 120 140 160

Time (d)

Tra

nsfe

r fa

cto

r (1

/kg)

OBT (HTO)

T (HTO)

OBT (OBT)

T (OBT)

Transfer factor for tritium

in broiler

0.01

0.1

1

0 20 40 60 80 100 120 140 160

Time (d)

Concentr

ation r

atio

OBT (HTO)

T (HTO)

OBT (OBT)

T (OBT)

Concentration ratio for tritium in

broiler

In the case of fast growing broiler, at the market weight of about 2 kg (42 days old) the model

predicts lower transfer factors (TF) than for the equilibrium case

The predicted concentration ratios (CR) for our fast growing broiler are close to those

obtained for “equilibrium” .

In absence of any experimental data or previous modelling assessments, our

results give a first view on the transfer of 3H and 14C in birds.

Extension to birds - application to broiler

CONCLUSIONS for animal model

• We developed a process level oriented model for mammals (human included), birds, and aquatic foodchain based on a unified approach – animals energetic;

• Model inputs are taken from Life Science research, concerning animal metabolism, nutrition and growth → Interdisciplinary Research;

• The aim was to develop a robust model avoiding calibration, in order to be used directly in practice

Open problems in OBT modelling in

crops

• Conversion of HTO to OBT imply HTO uptake

(and release), photosynthesis and respiration

and many biochemical reactions

• There is no deposition velocity but exchange

velocity

• OBT is produced also in night

• Clear dependence on genotype, crop specie,

development stage and environmental factors

• Large uncertainty in modeling

HYPO scenario EMRAS I

1 h HTO emission 10 g

at 1 km from stack

• Case 1 day Normalized by 6.109

Bq.s.m-3

• Case 3 night Normalized by 3.1011

Bq.s.m-3

Too large uncertainty. Greenpeace will be happy. Not me

TWT half-lives (min)

Plant

parts

Exposure at

dawn

(3 exp.)

Exposure at

day-time

(6 exp.)

Exposure at

dusk

(2 exp.)

Exposure at

night

(2 exp.)

Leaves 40-60 25-49 230-660 110-170

Stems 45-49 20-26 130-320 60-190

Ears 79-91 50-126 210-330 150-920

Total

plant

50-72 27-60 220-340 100-250

Half-Lives of TWT concentration in

wheat within 1 h after the end of

exposure to HTO

Dynamics of total OBT in wheat and rice

0

50

100

150

200

250

300

1h 2 h 1 d 7 d 28 d (harvest)

tota

l OB

T (

Bq

/pla

nt)

time after exposure

grains

husks

stems

leaves

Rice 4 days after flowering Wheat 20 days after flowering, ½ full light

Wheat 20 days after flowering at dusk

• Clear dependence on development

stage;

• Processes are complex and respiration

is very important;

• In the period of linear grain filling,

formation needs 2-5 days and thereafter,

it is a slow decreasing due to respiration

TLI comparison

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

development stage

TL

I (%

)

TLI spring w heat

TLI rice

TLI w inter w heat

TLI Korean soybean

TLI translocation index = the percentage of OBT concentration in grain

(edible plant part) at harvest (Bq mL-1 water of combustion) related to the TFWT

concentration in leaves (Bq mL-1) at the end of exposure to HTO

“Tritium is one of the most benign of radioactive materials

that I’ve worked with in my career, and I’ve worked with

many of them. But on the other hand, the perception of

tritium as a potential risk in the environment to the public

is huge; it is absolutely huge. It is the industry’s biggest

problem since the Three Mile Island accident in 1979.”

Dr. John E. Till, Author of

Risk Analysis for Radionuclides Released to

the Environment - Oxford University Press 2008

(but Chernobyl? And Fukushima !!)

CURRENT CHALLENGES:

NIGHT FORMATION OF OBT IN CROPS

HARMONIZATION FOR CONCEPTUAL MODEL

PREGNANT WOMEN AND FOETUS

OPERATIONAL MODEL DESIGN - GENERAL CONCEPT

Budget!

IAEA MODARIA

Acknowledgments - huge list

CONCLUSIONS