1. EMRAS II, Theme 3 WG tritium Develop Dynamic Tritium Model Tentative Working Group Leader: Dan Galeriu Assisted by S.L. Chouhan and P. Guetat Canada-France-Romania (CFR)

2. Aim and Objectives To develop a standard conceptual dynamic model for tritium dose assessment for acute releases to atmosphere and water bodies To focus on only starting the new model from the given air or water concentrations (HT or HTO) and the duration of the exposure To agree on common sub-models, based on understanding of the processes and agreed key parameters (interdisciplinary approach) 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

3. Justifications for an Improved Model Licensing and accident preparedness specific for utilities with large tritium inventory and tritium transport Uncertainties in the existing models are high. Models must incorporate new knowledge for credibility OBT (organically bound tritium) models need improvements (e.g. night time release are not well understood) Processes for tritium transfer and conversion under precipitation conditions need better understanding The dynamics of OBT and 14C concentrations were generally poorly reproduced in scenarios involving short-term releases EMRAS I-TRITIUM &14C

4. Interested Participants Romania ( IFIN-HH, SNN) >2 Canada (AECL, CNSC, Health Canada, COG) 4 France (CEA, EDF, IRSN, ?) >4 Slovakia (VUJE Inc) 1 Czech Republic (NRPI) 1 Mongolia (Nuclear Research Centre) 1 Germany (KFK, to be confirmed) >1 W Raskob need financing Ukraine (NIIEP) 1 More participants are welcome (Hopefully more participant may join the next meeting) Questionnaire on our needs will be spread ITER: to be requested; Japan Russia and USA

5. Immediate Provisional Working Plan (up to the next meeting) To check if TRS-364 can be partially used (do an example calculations for an acute release using a routine release model) To make available the existing models (i.e. ETMOD, UFOTRI, OURSON, RODOS and GAZAXI) to understand a way forward To establish a tritium modelling knowledge base (seek EMRAS-II website to host web page) To compile tritium experimental datasets (especially for transfer from air/soil/water to plants) To define the framework for linking from operational model (e.g. atmospheric dispersion model and site specific data) to the new conceptual tritium model Identify financial support Tentative WG meeting, September France

6. Long Term Provisional Working Plan To update the documentation in RODOS research for the new tritium model To use current research regarding animals model to construct a simple but robust new tritium model To collect data for constructing new plant model To gain knowledge from other experts (i.e. life scientists) regarding photosynthesis and water cycle in plants To optimize existing soil plant transfer model for tritium

7. End Result A new document covering acute release tritium model (Jan 2012)

8. NO steady state model can be adapted, as uptake and loss rate differs strongly - HTO visa OBT and environmental factor are depending on site conditions Pasture contamination Veal, just weaned at Accident time, on pasture until Age 300 d, clean food after until Sacrifice (500 kg) OBT predominate in meat

9. Using knowledge on Plant growth processes Testing with C experiments experiment simulation We can fix some Processes influencing T transfer and OBT formation Simplification latter, considering robustness in final dose and cost-benefit

10. No production near exclusion zone (except wine grapes) Town near- few local production Not flat terrain Building effect Moderate capacity for Improved ATM and meteorological sensors Operational model is site specific Framework will be given with specification on lost in dose assessment robustness

11. Potential participants now in VIC are kindly asked to complete their contact forms and to disseminate our intentions and needs of help We are only at the begin and future depends ON YOUR INVOVMENT AND POWER OF PERSUASION AT HOME