- Количество слайдов: 42
RESEARCH AND DEVELOPMENT OF ENVIRONMENTAL TRITIUM MODELLING Dan Galeriu, Anca Melintescu TRITIUM 2010, 24 -29 October 2010, Nara, Japan Time past and time future What might have been and what has been Point 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 and radio 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 (20072010) → Environmental Fate of Tritium in Soil and Vegetation • Autorite de Surete Nucleaire (France) → Livre Blanc TRITIUM (20082010) • 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)
TRITIUM and the ENVIRONMENT SOURCES MEASUREMENT and TRANSFER Ph GUETAT, CEA Thanks for their help to C Douche, JC Hubinois, N. Baglan , D Galeriu, Ph. Davis, W Raskob ******************* The levels specified for tritium in CODEX Alimentarius levels for radionuclides in foods contaminated following a nuclear or radiological emergency for use in international trade were derived generically for application to low energy beta emitters as a group. Significantly, different levels could result had they been derived explicitly for tritium. Given the ubiquitousness of tritium and its increasing importance in the context of fusion energy, consideration should be given to tritium being addressed explicitly in any future revision of CODEX Alimentarius – and of Euratom Council Regulation laying down maximum permitted levels of radioactive contamination of foodstuffs and of feeding stuffs following a nuclear accident or any other case of radiological emergency. 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 14 C models were also addressed because the dynamics of carbon and OBT are similar The uncertainty in the predictions of environmental tritium and 14 C 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 14 C 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, WG 2 - 3 H &14 C Scenario Type Scenario Leaders Participants Soybean H-3, Accidental, soybean plant KAERI Korea 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, 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 Canada, France, Germany, Japan, Korea, Romania, Russia, UK, USA Modelling the transfer of 3 H and 14 C into the environment - lessons learnt from IAEA’s EMRAS project, A. Melintescu, D. Galeriu, Radioprotection, Vol. 44, No. 5, (2009), 121 – 127
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, 14 C AND 36 Cl 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. Takeda Journal 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
How to obtain an useful model? SPECIFIC CAUSES OF 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 - 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, Ph. D 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
Overview of 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 UNRESTRICTED / ILLIMITÉ
S. Strack, Experiments with Tritium in Wheat
List of publications related to D 2 O experiments • • • Deposition of D 2 O from air to plant and soil during an experiment of D 2 O 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 D 20 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. 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 D 2 O 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
Role of plant growth processes and physiology (14 C example) Gross photosynthesis Assimilate accumulation Growth and maintenance Respiration Partition to plant parts Role of reserves DEVELOPMENT STAGE GP*Yo grain gresp assim Struct. assim body reserve maintenance root 0. 045 0. 04 Rice, Japan Controlled experiment B. Tani et al. , IES 2007 Model for close genotype and Tokaimura weather SAR ratio of specific activity Specific activity of 14 C (14 C/total C, Bq/g C) in the edible part of crops specific activity of 14 C in air (Bq/g C) SARTANI SAR(grain/air) 0. 035 SARMY 0. 03 0. 025 0. 02 0. 015 0. 01 0. 005 0 -60 -10 DRA (d) 40 90
Land surface model SOLVEG 2 OBT formation and translocation 19/18 Carbohydrate formation and translocation processes based on experimental result (Fondy & Geiger 1982) Daytime Nighttime CO 2 assimilation rate An OBT formation: EAn 1. 00 EAn 0. 48 EAn sucrose 0. 46 EAn OBT decomposition: ERd 0. 26 EAn intermediates Respiration rate Rd structural 1. 00 ERd intermediates structural 0. 19 EAn 4. 58 ERd starch sucrose starch Translocation 5. 23 ERd Translocation Haruyasu Nagai, Masakazu Ota 7. 07 ERd
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 3 H and 14 C 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) E=mc 2 → GE in food GEf DE GEug ME Basal Met. Maint. Met. Heat of Dig. Cold Therm. Used for work, Growth, re-prod NE The mean value of θ − 1 gives the mean residence time of chemical elements in the living 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 3 H and 14 C 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 14 C and 3 H in animals Radiat. Environ. Biophys. (2010), DOI: 10. 1007/s 00411 -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 3 H and 14 C transfer, obtained from experiments with Wistar strain rats thanks to H. Takeda (NIRS, Japan) continuous 98 days intakes of 14 C and OBT contaminated food or HTO; acute intakes of HTO or 14 C and 3 H labelled glucose, leucine, glycine, lysine, and oleic and palmitic acids. Available data include 14 C, OBT and HTO measurements in visceral organs, muscle, adipose tissue, brain, blood and urine. 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 Organ 14 C chronic 14 C 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
Mass dependence (relative units) for viscera mass fraction, specific metabolic rates SMR ((MJ kg-1 day-1) and partition fractions for maintenance metabolic energy of growing ruminants Viscera mass Relative body fraction weight normalized (EBW/SRW) to EBW Specific metabolic rate (MJ kg-1 day-1) Partition fraction maintenance metabolism liver Liver+PDV Adipose PDV HQ 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 0. 023 0. 61 0. 27 0. 097 0. 3 0. 12 NA NA 0. 04 0. 61 0. 31 0. 04 0. 41 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. 31 0. 04 1 0. 08 NA NA 0. 19 0. 47 0. 3 0. 04
Tests with growing pigs and veal Few experiments 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: Not quite sure about these values → Potential Muscle P/O ~ 0. 2 explanation: old and insufficiently reported Viscera P/O ~ 0. 3 experimental data 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
Short term dynamics of 14 C in whole body (generalised coordinates) - Wild animals Generalised coordinates: Normalised concentration=Whole body conc *Mature mass T*RMR – non-dimensional time = time * mature RMR Despite these shortcomings, the results presented above are less uncertain than for many other radionuclides and can provide useful results for biota radioprotection.
Extension to birds - application to broiler Transfer factor for tritium in broiler 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 3 H and 14 C in birds.
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 1980 s 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 (Mc. Cubbin 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 3 H into particulate matter (via bacterial uptake / physico-chemical sorption) and the subsequent transfer to the foodchain (Mc. Cubbin 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
AQUAtic TRITium - an update (see Dynamic model for tritium transfer in aquatic food chain, A. Melintescu, D. Galeriu, submitted to Radiat. Environ. Biophys. ) • We introduced the direct uptake of DOT in the dynamic eqs. for autotrophes (phytoplankton, benthic algae) and consumers (invertebrates, fishes): 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 -1 fw day-1) Simplification of Michaelis Menten equation in practical application The growth rate μ depends on nutrients, light and temperature The coefficients a and b depends on SAR and OBT loss rate K 05 (reflects processes when only HTO is primary source) Cf depends on prey preference and availability K 05 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 m 3 s-1,
In practice, an incident with tritium loss in Danube River can occur any time and it will 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 (m 3 s-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. 4 a b 0. 5 kg of a mixture of carp and zander 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).
DOT- The Cardiff case 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
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 OBT retention, an age-dependent biokinetic model for dietary intakes of OBT should be developed. 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 metabolic model. Derivation of parameters and application of the model to the general public and to workers D. Galeriu and A. Melintescu JOURNAL OF RADIOLOGICAL PROTECTION 30 (2010) 445– 468 (31/08/2010) Extension of Reassessment of tritium dose coefficients for general public A. Melintescu, D. Galeriu, H. Takeda Radiation Protection Dosimetry, 127 (1 -4): 153 -157, 2007 Energy Metabolism and Human Dosimetry of Tritium D Galeriu, H Takeda, A. Melintescu, A Trivedi Fusion Science and Technology, Vol. 48, Number 1 – July/August 2005, P. 795 -798
Flowchart of model for humans Organ-specific metabolic rates (SMR) for adults in basal state 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
ROLE OF BRAIN Glucose utilization (metabolic rate) for cortex region at various human ages Reconstruction of basal metabolic rate
TESTS with human experimental data; HTO intake (left), OBT intake (right) NO other model was tested with OBT experimental data
Integrated concentrations for model compartments (Bq d kg-1 fw) after a single unit intake 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. 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 Tritium concentration (Bq kg-1 fw) after 3000 days of continuous HTO intake (1 k. Bq d-1) 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
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) 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 15 years 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 w. T; E – non uniform distribution to be compared with ICRP Moderate increase, but infant a factor 2 Use bioassay Total T and OBT in urine after HTO or OBT intake SATISFIES THE RECENT REQUIREMENTS Dynamics of OBT in blood plasma and red blood cells OBT after an OBT intake of 1000 Bq
CONCLUSIONS “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? ) TODAY CHALENGES: NIGHT FORMATION OF OBT IN CROPS HARMONIZATION FOR CONCEPTUAL MODEL PREGNANT WOMEN AND FOETUS OPERATIONAL MODEL DESIGN - GENERAL CONCEPT Welcoming China, USA, Russia Budget! Acknowledgments - huge list
Thank you for your attention!