RESEARCH AND DEVELOPMENT OF ENVIRONMENTAL TRITIUM MODELLING

Dan Galeriu, Anca Melintescu

TRITIUM 2010, 24-29 October 2010, Nara, Japan

Time past and time futureWhat might have been and what has beenPoint to one end, which is always present

T.S. Eliot: Burnt Norton (I), Four Quartets (1943)

WHY?

CANDU Reactors in Romania

The future Fusion Reactor

TRITIUM - LOW risk, but how low?

Dose coefficients andradio toxicity → tritium is good

The AIKEN list (1990) →Tritium is not well handled

THE CONTEXT ON 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

• 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

• Working Group 2 - Modelling of Tritium and Carbon-14 transfer to biota and man working group

• Working Group 7 – "Tritium" Accidents (on going)

TRITIUMTRITIUM and the ENVIRONMENTand the ENVIRONMENT

SOURCES MEASUREMENT and TRANSFERSOURCES MEASUREMENT and TRANSFER

Ph GUETATPh GUETAT, , CEACEA

Thanks for their help to C Douche, JC Hubinois, N. Baglan , Thanks for their help to C Douche, JC Hubinois, N. Baglan ,

D Galeriu, Ph. Davis, W RaskobD Galeriu, Ph. Davis, W Raskob

**************************************************************************The levels specified for tritium in CODEX Alimentarius levels for radionuclidesin foods contaminated following a nuclear or radiological emergency for use ininternational trade were derived generically for application to low energy betaemitters as a group. Significantly, different levels could result had they beenderived explicitly for tritium. Given the ubiquitousness of tritium and itsincreasing importance in the context of fusion energy, consideration should begiven to tritium being addressed explicitly in any future revision of CODEXAlimentarius – and of Euratom Council Regulation laying down maximumpermitted levels of radioactive contamination of foodstuffs and of feedingstuffs following a nuclear accident or any other case of radiologicalemergency.

CEA/DAM/VA UE Scientific Seminar on Emerging Issues on Tritium

Canadian and French conclusions(routine emissions)

• OBT activities measured in soils and plants have significantly higher variability than the corresponding HTO concentrations, and the OBT/HTO ratios for soils, plants and animal products have large variations;

• Near nuclear sites, the average OBT/HTO ratios are a factor 2-3 for plant products and 10 for animal products. These ratios are significantly higher than those predicted by the current physiological models of HTO and OBT behaviour in plants and animals; it seems that imported feed from areas contaminated with high tritium levels is an explanation for such OBT/HTO ratios in animal products;

• There is a need for a relatively simple dynamic model for OBT formation and retention in an environment subject to fluctuating HTO concentrations, as it is encountered in practice;

• An age dependent biokinetic model for the OBT retention should be developed for infants, children and adults, which accounts for physiological and anatomical variation with age;

• OBT levels in river sediments are always larger than those in plants and fish, which themselves are larger than HTO concentrations in river water. This clearly demonstrates the existence of OBT pools in the environment with slow turnover rates and low bioavailability;

• High OBT in soil is not a significant secondary source of tritium, even for humic soils with a large decomposition rate of OBT;

• The case of high OBT in fish (in Cardiff Bay, for example) needs more clarification and the effect of organic precursors must be studied;

• The state of modelling reflects the present knowledge and more efforts must be done concerning the OBT.

Tritium results in EMRAS I Modelling of Tritium and Carbon-14 transfer to biota and man working group

The activities of the WG focused on the assessment of models for organically bound tritium (OBT) formation and translocation in plants and animals, the area where model uncertainties are largest. Environmental 14C models were also addressed because the dynamics of carbon and OBT are similar

The uncertainty in the predictions of environmental tritium and 14C models can be reduced by:

• Ensuring that the air concentrations used to drive the models are of high quality and match the resolution and averaging requirements of the scenario. Performance was better for models that were driven by air concentrations averaged over the OBT or 14C residence time in the compartment of interest;

• incorporating as much site-specific information as possible on land use, local soil properties and predominant plant cultivars and animal breeds;

• implementing realistic growth curves for the plant cultivars of interest;

• basing all sub-models on the physical approaches available for the disciplines in question. For example, knowledge from the agricultural sciences should be used to improve models for crop growth, photosynthesis and translocation;

• recognizing and accounting for any unusual conditions (water stress, an uncommon cultivar or breed) in the model application.

IAEA EMRAS I, WG2 - 3H &14C

Modelling the transfer of 3H and 14C into the environment - lessons learnt from IAEA’s EMRAS project, A. Melintescu, D. Galeriu, Radioprotection, Vol. 44, No. 5, (2009), 121 – 127

Scenario Type Scenario Leaders Participants

Soybean H-3, Accidental, soybean plant KAERI Korea Canada, France, Germany, Japan, Korea, Romania, Russia, UK, USA

Perch Lake H-3 Routine, aquatic AECL Canada Russia, France, Germany, Romania, Japan, UK, Lithuania

Pickering H-3 Routine, terrestrial AECL Canada Germany, USA, Lithuania, UK, Romania, Japan, France

Pine tree H-3, routine, tree, groundwater NIRS Japan Japan, USA, Romania, France

Rice C-14, routine, rice JAEA Japan Canada, France, Romania, Japan

Hypothetical H-3, accidental, terrestrial CEA France Canada, Romania, Korea, Japan, France, Germany, India

Mussel H-3, accidental, aquatic - mussel AECL Canada Germany, France, Japan, Romania

C-14 potato C-14, accidental, potato plant NIPNE Romania France, UK, Romania, Japan

Pig H-3 (OBT) - complex - pig NIPNE Romania Japan, Romania, France, Canada, UK

IAEA Technical Reports Series No. 472

Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Terrestrial and Freshwater Environments

Chapter 10. SPECIFIC ACTIVITY MODELS AND PARAMETER VALUES FOR TRITIUM, 14C AND 36Cl

incorporate:

Modelling H-3 and C-14 transfer to farm animals and their products under steady state conditions

D. Galeriu, A. Melintescu, N.A. Beresford, N.M.J. Crout, R. Peterson H. TakedaJournal of Environmental Radioactivity, 98 (2007) 205 - 217

IAEA-EMRAS II (on going, 2009 - 2012) Reference Approaches for Human Dose Assessment

Working Group 7 “Tritium” Accidents

Aims and Objectives:

• To develop a standard conceptual dynamic model for tritium dose assessment for acute releases to atmosphere and water bodies;

• To start to develop a new model for any air or water concentration (HT or HTO) and the duration of the exposure - The operational model will be developed by each major user considering available best Atmospheric Transport Models for the site in question;

• To agree on common sub-models, based on understanding of the processes and agreed key parameters (interdisciplinary approach), based on recent findings in Life Sciences;

• To define the framework for an operational model;

• To obtain quality assured sub-models and harmonize approaches in order to get confidence in the predictions (moderate conservatism);

• To have capability to assimilate real data from measurements

Task groups and few results

Task Group I – Wet deposition • Sensitivity analysis of rain characteristics on HTO concentration in drops, L.

Patryl, D. Galeriu, P. Armand, L. Vichot, Ph. Guétat, this conference

• Rain scavenging of tritiated water vapour: A numerical Eulerian stationary model, D. Atanassov, D. Galeriu, J. Environ. Radioact., doi:10.1016/j.jenvrad.2010.09.001

• Tritium profiles in snowpacks, D. Galeriu, P. Davis, W. Workman, J. Environ. Radioact., 101 (10), p. 869-874, October 2010

Task Group II Aquatic pathways (EDF,IFIN, Brazil) • Modelling tritium flux from freshwater to atmosphere: application to the Loire

river, L. Marang, F. Siclet, et al., this conference• Organically bound tritium in freshwater ecosystems : long term trends in the

environment of nuclear power stations, F. Siclet, G. Gontier, this conference

Task Group III - Terrestrial pathway (atmospheric source) • All WG 7 participants• P. Guetat, P. Cortez, N. Momoshima, A. Melintescu, L. Patryl, L. Vichot, S.B.

Kim, V. Korolevich – papers at this conference

Hydrological model for tritium dispersion after a release of 37 PBq

Dispersion of HTO plume after 3 days following the accident in the scenario 1

F. Lamego, Institute of Nuclear Engineering, Rio de Janeiro, Brazil

Regulatory requirements for a model

• Relatively simple;• Transparent ;• Easy to program;• Results should be conservative (but not too

much);• Deterministic calculations possible (worst case

assessments);• Probabilistic calculations possible (95%

percentile as worst case); • Is this possible for Tritium?

Tritium Modelling Overview, W. Raskob, EMRAS January 2010

SPECIFIC CAUSES OF UNCERTAINTY

- Missing communication;- Experiments and OBT modelling at AECL - undisclosed;- Cardiff case - experiments - undisclosed (but reports from Environmental Agency and FSA are available on request);- Many reports, PhD thesis difficult to access or delayed for accessing;- Incomplete documentation – ignoring past achievements (BIOMOVS, EMRAS I, selective uptake of DOT);- No common knowledge data base due to copyright restriction;- Missing appreciation – S Strack case - lost information for T in wheat;- Limits in allocation of time and budget- Missing dedication - only a job- Missing peer review- Insufficient parameter uncertainty

Simple model - Keum et al.,Health Physics, January 2006,Volume 90, p.42

Very complex model, M. Ota &H. Nagai, EMRAS WG 7 presentation

How to obtain an useful model?

UNRESTRICTED / ILLIMITÉ

OverviewOverviewof ETMOD and Environmental Tritium Researchof ETMOD and Environmental Tritium Research

September 28-29, 2009

Ph.D. S.B. Kim

Research Scientist

Environmental Technologies Branch

Chalk River Laboratories

Chalk River, Ontario

Canada

S. Strack, Experiments with Tritium in Wheat

List of publications related to D2O experiments

• Deposition of D2O from air to plant and soil during an experiment of D2O vapor release into a vinyl house, Mariko Atarashi, Hikaru Amano, Michiko Ichimasa, Yusuke Ichimasa, Fusion Engineering and Design 42 (1998) 133–140

• Formation and retention of organically bound deuterium in rice in deuterium water release experiment, M. Atarashi-Andoh, H. Amano, H. Kakiuchi, M. Ichimasa and Y. Ichimasa, Heaoth Physics, 82, 863-868 (2002).

• Uptake of heavy water vapor from atmosphere by plant leaves as a function of stomatal resistance, M. Atarashi, H. Amano, M. Ichimasa, M. Kaneko and Y. Ichimasa, Proceedings of International Meeting on Influence of Climatic Characteristics upon Behavior of Radioactive Elements, Rokkasho, Aomori, Japan, October 14-16, 1997, Edited by Y. Ohmomo and N. Sakurai, IES, 236-242 (1997).

• Conversion rate of HTO to OBT in plants, M. Atarashi-Andoh, H. Amano, M. Ichimasa and Y. Ichimasa, Fusion Science and Technology, 41, 427-431 (2002).

• Uptake kinetics of deuteriated water vapor by plants: Experiments of D20 release in a greenhouse as a substitute for tritiated water, N. Momoshima, H. Kakiuchi, T. Okai, S. Yokoyama, H. Noguchi, M. Atarashi, H. Amano, S. Hisamatsu, M. Ichimasa, Y. Ichimasa, Y. Maeda, Journal of Radioanalytical and Nuclear Chemistry, Vol. 239, No. 3 (1999) 459-464

• Uptake of deuterium by dead leaves exposed to deuteriated water vapor in a greenhouse at daytime and nighttime, N. Momoshima, R. Matsushita, Y. Nagao and T. Okai, J. Environ. Radioactivity,88, 90-100 (2006).

• Organically bound deuterium in soybean exposed to atmospheric D2O vapor as a substitute for HTO under different growth phase, M. Ichimasa, T. Maejima, N. Seino, T. Ara, A. Masukura, S. Nishihiro, H. Tauchi and Y. Ichimasa, Proceedings of the International Symposium: Transfer of Radionuclides in Biosphere –Prediction and Assessment-, Mito, December 18-19, 2002, JAERI-Conf 2003-010, 226-232 (2003).

• Heavy water vapor release experiment in a green house –Transfer of Heavy water to tomato and dishcloth gourd—, M. Ichimasa, T. Hakamada, A. Li, Y. Ichimasa, H. Noguchi, S. Yokoyama, H. Amano and M. Atarashi, Proceedings of International Meeting on Influence of Climatic Characteristics upon Behavior of Radioactive Elements, Rokkasho, Aomori, Japan, October 14-16, 1997, Edited by Y. Ohmomo and N. Sakurai, IES, 243-248 (1997).

• Organically bound deuterium in rice and soybean after exposure to heavy water vapor as a substitute for tritiated water, M. Ichimasa, C. Weng, T. Ara and Y. Ichimasa , Fusion Science and Technology, 41, 393-398 (2002).

• Deposition of heavy water on soil and reemission to the atmosphere, Sumi Yokoyama, Hiroshi Noguchi, Michiko Ichimasa, Yusuke Ichimasa, Satoshi Fukutani, Fusion Engineering and Design 42 (1998) 141–148

• Re-emission of heavy water vapor from soil to the atmosphere, S. Yokoyama, H. Noguchi, Y. Ichimasa and M. Ichimasa, Journal of Environmental Radioactivity, 71, 201-213 (2004).

N. Momoshima, WG 7, Paris meeting Sept 2009

grain

body

reserve

Struct. assim

assim

maintenance

gresp

root

GP*Yo

Role of plant growth processes and physiology (14C example)

Gross photosynthesisAssimilate accumulationGrowth and maintenanceRespirationPartition to plant partsRole of reservesDEVELOPMENT STAGE

Rice, JapanControlled experiment B. Tani et al., IES 2007 Model for close genotype and Tokaimura weatherSAR ratio of specific activitySpecific activity of 14C (14C/total C, Bq/g C) in the edible part of crops specific activity of 14C in air (Bq/g C)

Carbohydrate formation and translocation processes

based on experimental result (Fondy & Geiger 1982)

Land surface model SOLVEG2OBT formation and translocation

Daytime Nighttime

0.19EAn0.48EAn

0.26EAn1.00EAn

starch

0.46EAn

1.00ERd

4.58ERd

5.23ERd

7.07ERd

intermediatesintermediates

sucrosesucrose starch

structuralstructural

Translocation Translocation

CO2 assimilation rate An Respiration rate Rd

OBT formation: EAn OBT decomposition: ERd

19/18

Haruyasu Nagai, Masakazu Ota

Heat and life: The ongoing scientific

odyssey (key for OBT in animals)

• The technocratic model stresses mind-body separation and sees the body as a machine;

• The humanistic model emphasizes mind-body connection and defines the body as an organism;

• The holistic model insists on the oneness of body, mind, and spirit and defines the body as an energy field in constant interaction with other energy fields.

Animals bioenergetics

• Review of past results of 3H and 14C transfer modelling in mammals → necessity to have a common approach based on energy needs and on the relation between energy and matter Knowledge on animal metabolism and nutrition

• Metabolism = countless chemical processes going on continuously inside the body that allow life and normal functioning

• These processes require energy from food • Gross energy, Digestible energy,

Metabolisable Energy, Net energy• Maintenance metabolism (basal+heat of

digestion), lost as heat• Heat needed for cold thermogenesis, activity

and losses in processes of growth, production and reproduction

• Energy stored (deposited, retained) in the products of growth, lactation (egg) and reproduction

• Daily Energy Expenditure (Field Metabolic Rate)

GE in food

GEf

DE

GEug

ME

Basal Met.

Heat of Dig.

Maint. Met.

Cold Therm.

Used for work, Growth, re-prod

NE

dt

dM

Mdt

dE

E

11E=mc2 →

The mean value of θ −1 gives the meanresidence time of chemical elements in theliving body

MAGENTC - MAmmal GENeral Tritium and Carbon transfer

• Complex dynamic model for H-3 and C-14 transfer in mammals, description in:D. Galeriu, A. Melintescu, N. A. Beresford, H. Takeda, N.M.J. Crout, “The Dynamic transfer of 3H and 14C in mammals – a proposed generic model”, Radiat. Environ. Biophys., (2009) 48:29–45 A. Melintescu, D. Galeriu Energy metabolism used as a tool to model the transfer of 14C and 3H in animals Radiat. Environ. Biophys.(2010), DOI: 10.1007/s00411-010-0302-4

- 6 organic compartments;- distinguishes between organs with high transfer and metabolic rate (viscera), storage and very low metabolic rate (adipose tissue), and ‘muscle’ with intermediate metabolic and transfer rates; - Blood - separated into RBC and plasma (plasma is the vector of metabolites in the body and also as a convenient bioassay media);-The remaining tissues - bulked into “remainder”;- All model compartments have a single component (no fast-slow distinction)

Model tests with experimental data - NO calibration (rat, cow, sheep, pig)

Complete database for 3H and 14C transfer, obtained from experiments with Wistar strain rats thanks to H. Takeda (NIRS, Japan)

continuous 98 days intakes of 14C and OBT contaminated food or HTO; acute intakes of HTO or 14C and 3H labelled glucose, leucine, glycine, lysine, and oleic and palmitic acids.

Available data include 14C, OBT and HTO measurements in visceral organs, muscle, adipose tissue, brain, blood and urine.

Organ 14C chronic 14C acute OBT chronic OBT acute HTO chronic HTO acute

Viscera 1.12 ± 0.15 0.51 ± 0.4 1.06 ± 0.15 0.67 ± 0.56 0.43 ± 0.07 0.87 ± 0.34

Muscle 1.25 ± 0.14 0.81 ± 0.29 1.23 ± 0.21 0.90 ± 0.37 0.40 ± 0.09 1.02 ± 0.38

Adipose 1.11 ± 0.15 0.61 ± 0.12 0.97 ± 0.2 0.75 ± 0.13 0.3 ± 0.1 1.33 ± 0.3

Whole blood 1.12 ± 0.27 0.4 ± 0.1 0.88 ± 0.12 0.38 ± 0.03 0.37 ± 0.09 0.62 ± 0.18

Whole-body 1.18 ± 0.08 0.7 ± 0.1 1.08 ± 0.11 0.8 ± 0.1 0.36 ± 0.08 1.09 ± 0.18

Average and standard deviation of predicted to observed ratios in rat viscera, muscle,

blood, adipose tissue and whole body (except bone and skin) for the six forms of intake

Mass dependence (relative units) for viscera mass fraction, specific metabolic rates -

SMR ((MJ kg-1day-1) and partition fractions for maintenance metabolic energy of growing ruminants

Relative body weight(EBW/SRW)

Viscera mass fractionnormalized to EBW

Specific metabolic rate (MJ kg-1day-1) Partition fraction maintenance metabolism

liver PDV HQ Liver+PDVAdipose viscera muscle remainder

0.07 0.09 1.5 0.77 0.24 0.98 0.006 0.47 0.42 0.104

0.2 0.11 NA NA NA NA 0.023 0.61 0.27 0.097

0.3 0.12 NA NA NA NA 0.04 0.61 0.31 0.04

0.41 NA* NA NA NA NA 0.068 0.61 0.27 0.052

0.48 NA 2.9 0.47 0.1 0.83 0.094 0.6 0.27 0.036

0.64 NA 2.6 0.36 0.088 0.66 0.13 0.55 0.29 0.042

0.77 NA 2.4 0.3 0.084 0.55 0.15 0.5 0.31 0.04

1 0.08 NA NA NA NA 0.19 0.47 0.3 0.04

Tests with growing pigs and veal

1. Pigs of 8 weeks old fed for 28 days with HTO:Muscle P/O ~ 1Viscera P/O ~1

2. Pigs of 8 weeks old fed for 28 days with milk powder contaminated with OBT:Muscle P/O ~ 3Viscera P/O ~ 2

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

Muscle P/O ~ 0.2Viscera 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 ~ 1Viscera P/O ~ 2.5

Few experiments

Not quite sure about these values → Potential explanation: old and insufficiently reported experimental data

1 2 3 4 5 6 7 8 9 100.01

0.1

no

rm w

ho

le c

onc

T*RMR

lemming chipmunk chipmunkC rabbit redfox reddeer

Short term dynamics of 14C in whole body (generalised coordinates) - Wild animals

Despite these shortcomings, the results presented above are less uncertain than for many other radionuclides and can provide useful results for biota radioprotection.

Generalised coordinates:Normalised concentration=Whole body conc *Mature massT*RMR – non-dimensional time = time * mature RMR

0.01

0.1

1

10

100

0 20 40 60 80 100 120 140 160

Time (d)

Tran

sfer

fact

or (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)

Conc

entra

tion

ratio

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 - MAGENTC

• The model is apparently research grade, but it is tested with experimental data without calibration;

• It is continuously improved in parallel with literature search on animal nutrition and metabolism;

• Input parameters need only a basic understanding of metabolism and nutrition and the recommended values can be provided;

• Results give arguments for distinction between subsistence and intensive farming (observed also for Cs-137 post-Chernobyl);

• Model provides robust results for all intake scenarios of interest

AQUAtic TRITium, an update (in reply to Livre Blanc Tritium)

The models used in 1980s were based on the assumption that the OBT SA in fish is directly linked with the HTO in water or the OBT in fish food → fully valid if the water contamination is due only to an initial HTO source → CF ≤ 1

CF = concentration per unit mass of biota at equilibrium / dissolved concentration per unit volume in ambient water

CFs in marine biota at Cardiff Bay (UK) much higher in flounder and mussels (McCubbin et al., 2001; Williams et al., 2001)CFs ≥4 × 103 (fw equivalent) → attributed to uptake of tritium in organically bound forms, due to the existence of organic species of tritium in a mixture of compounds in the authorised releases of wastes to the Bristol Channel from the Nycomed-Amersham (now GE Healthcare) radiopharmaceutical plant at Whitchurch, Cardiff, UK The extremely high CFs can’t be explained by analytical errors (Hunt et al., 2010)Advanced hypotheses:

- concentration of organic tritium by bacteria and subsequent transfer in the food chain; - ingestion of contaminated sediment; - ingestion of contaminated prey;- direct uptake of DOT (DISOLVED ORGANIC TRITIUM) from the sea water;- bioaccumulation occur via a pathway for the conversion of the organic compounds

labelled with dissolved 3H into particulate matter (via bacterial uptake / physico-chemical sorption) and the subsequent transfer to the foodchain (McCubbin et al., 2001) →not valid, because monitoring data on sediment and suspended matter compared with data on tritium in benthic fauna show that the ingestion of sediment or particulate matter is not a reasonable explanation

• We introduced the direct uptake of DOT in the dynamic eqs. for autotrophes

(phytoplankton, benthic algae) and consumers (invertebrates, fishes):

phploDOTDOTWphplo CCVCDryf

dt

dC,

, *001.04.0

CK-CV(t)Cb+tCa= dt

dCxorgx0.5DOTDOTwxxfx

xorg,,,

, )(

CW - HTO concentration in water (Bq m-3); CDOT - the dissolved organic tritium concentration (Bq L-1); VDOT - the uptake rate of DOT (L kg -1fw day-1)Simplification of Michaelis Menten equation in practical application

AQUAtic TRITium - an update (see Dynamic model for tritium transfer in aquatic food chain, A. Melintescu, D. Galeriu, submitted to Radiat. Environ. Biophys.)

The growth rate μ depends on nutrients, light and temperatureThe coefficients a and b depends on SAR and OBT loss rate K05

(reflects processes when only HTO is primary source)Cf depends on prey preference and availability K05 depends on species, mass, temperature and pray availability

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

once

ntra

tion

(Bq/

kg fw

)

phytoplankton

zooplankton

zoobenthos

benthic algae

molluscs

carp

pike

roach

In practice, an incident with tritium loss in Danube River can occur any time and itwill be useful to understand the seasonal effect of the release impact on human ingestion coming from fish. Across the years, the Danube River’s flow and temperature vary and for the same release of 3.7 PBq of tritium for 6 hours, the fish contamination varies also

Date of release River flow (m3s-1) River temperature (°C)

Ingested activity of fish (Bq)a % OBTb

February 15 3000 3 22844 3

April 15 5000 10.5 14348 7.3

May 15 3500 17 21831 13

July 15 1500 24 63377 30

September 15 1000 20 92430 28

October 15 1500 15 53790 17.5

December 15 1500 5.5 46415 4.4a 0.5 kg of a mixture of carp and zanderb The percentage of OBT coming from the ingested fish activity

Water temperature has a large influence on the OBT content in fish and the highest impact is in late summer (September 15).

1000

10000

100000

1000000

0 2000 4000 6000 8000 10000 12000time (day)

Tri

tiu

m c

on

cen

trat

ion

(B

q/k

g f

w)

mussel (model)

flounder (model)

mussel (exp)

flounder (exp)

For the 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 as: 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

CONCLUSIONS

• In the late 1980, the aquatic pathways after releases of tritium (HTO) were not considered of relevance (Blaylock et al., 1986) and simple models were used based on specific activity approach.

• The occurrences of high concentration factors in Cardiff area generate debate and public concern for the development of nuclear pharmaceutical production.

• The present model intends to be more specific than a screening model, including a metabolic approach and the direct uptake of DOT in marine phytoplankton and invertebrates.

• The high concentration factors found in Cardiff area are not a general problem of nuclear industry. The Cardiff case reflects a specific biological process in marine invertebrates and the consequences were ignored in the past.

• In order to have a better control of tritium transfer into the environment, not only tritiated water must be monitored, but also the other chemical forms and mainly, OBT in food chain.

To address the retention of OBT in children and the effect of organ growth on OBTretention, an age-dependent biokinetic model for dietary intakes of OBT should bedeveloped. This model would need to include all age groups, including the nursing

infant, and account for physiological and anatomical variations associated with age CNSC Tritium Studies Project Synthesis Report June 2010

Retention of tritium in reference persons: a metabolicmodel. Derivation of parameters and application of themodel to the general public and to workers

D. Galeriu and A. Melintescu

JOURNAL OF RADIOLOGICAL PROTECTION30 (2010) 445–468 (31/08/2010)

Extension ofReassessment of tritium dose coefficients for general publicA. Melintescu, D. Galeriu, H. TakedaRadiation Protection Dosimetry, 127 (1-4):153-157, 2007 Energy Metabolism and Human Dosimetry of TritiumD Galeriu, H Takeda, A. Melintescu, A TrivediFusion Science and Technology, Vol. 48, Number 1 – July/August 2005, P.795-798

Red Blood Cell (RBC)

Brain (BR)

Viscera (VIS)

Muscle (MUS)

Adipose Tissue (AD)

Remainder (REM)

BloodPlasma

(BP)

FBP→RBC

FRBC→BP

FBP→BR

FBR→BP

FBP→VIS

FVIS→BP

FBP→MUS

FMUS→BP

FBP→AD

FAD→BP

FBP→REM

FREM→BP

Stomach Content(ST)

BodyWater(BW)

Small Intestine Content (SI)

Large IntestineContent (LI)

HTOIntake

OBTIntake

FBW→BP

FBP→BW

FSI→BW

FSI→BP

FST→SI

FSI→LI

FBP→uo

Excretion of OBT in urine

FBW→out Organ SMR (MJ kg-1 fw d-1)

brain 1.008

liver 0.84

heart 1.841

kidney 1.841

muscle 0.055

adipose 0.019

bone 0.00963

lung 0.5

GIT 0.35

Skin 0.025

Residual* 0.014

Organ-specific metabolic rates (SMR) for

adults in basal state Flowchart of model for humans

ROLE OF BRAIN

mass fraction

0%10%

20%30%

40%50%

60%70%

80%90%

100%

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

muscle

brain

adipose

remainder

viscera

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

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

once

ntra

tion

(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)

OBT

conc

entra

tion

(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

Time (d)

Per

cent

of

inta

ke

exp

model

OBT in urine

0.001

0.01

0.1

1

10

0 50 100 150

Time (d)

Pe

rce

nt o

f in

take

exp

model

TESTS with human experimental data; HTO intake (left), OBT intake (right)

NO other model was tested with OBT experimental data

Case HTO* OBT# Adipose Muscle Viscera Residual RBC Brain

3 months OBT 1.21 2.87 9.28 0.948 2.13 1.69 1.95 0.710

10 years OBT 0.469 0.831 2.37 0.365 0.552 0.415 0.463 0.466

adult female OBT 0.348 0.909 2.01 0.339 0.513 0.429 0.431 0.433

adult male OBT 0.307 0.551 1.52 0.256 0.387 0.305 0.325 0.327

adult male HTO 0.341 0.0327 0.09 0.0152 0.023 0.0181 0.0193 0.0194

* Tritium concentration in body water;# Tritium concentration in all organic compartments

Integrated concentrations for model compartments (Bq d kg-1 fw) after a single unit intake

T conc. (Bq kg-1 fw) blood plasma RBC adipose muscle viscera residual brain whole

OBT 5 19 88 15 23 19 19 32.1

HTO 330 220 73 270 250 160 270 205

Total T 340 240 160 290 270 180 290 237.1

Tritium concentration (Bq kg-1 fw) after 3000 days of continuous HTO intake (1 kBq d-1)

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

0.1 1 10 100 1000

time (d)

Con

c. (B

q/kg

dm

)

O_bloodpl(OBT)

O_RBC(OBT)

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 ICRPModerate increase, but infant a factor 2

0.0001

0.001

0.01

0.1

1

10

-1 19 39 59 79 99

time (d)

% e

xcre

ted p

er d

ay

totT_hto

totT_obt

OBT_hto

OBT-obt

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

“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 publicis huge; it is absolutely huge. It is the industry’s biggestproblem 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?)TODAY CHALENGES:NIGHT FORMATION OF OBT IN CROPSHARMONIZATION FOR CONCEPTUAL MODELPREGNANT WOMEN AND FOETUSOPERATIONAL MODEL DESIGN - GENERAL CONCEPTWelcoming China, USA, RussiaBudget!

Acknowledgments - huge list

CONCLUSIONS

Thank you for your attention!