Fusion Science and Technology / Volume 48 / Number 1 / July 2005 / Pages 492-495
Technical Paper / Tritium Science and Technology - Containment, Safety, and Environment
Deterministic and probabilistic dose assessments for releases of tritium have been performed for the potential European ITER Site of Vandellós (Spain). Besides national regulatory models, internationally accepted computer codes such as NORMTRI (for normal conditions) and UFOTRI (for incidental/accidental conditions) were used for the calculations. The paper concentrates on releases of tritium in either HT or HTO form. Source terms from the ITER documentation (GSSR vol. IV and VII) have been used for the HT/HTO releases.
The data base of NORMTRI/UFOTRI was adapted to the national regulatory prescriptions. This comprised in particular ingestion habits and dose conversion factors. Important for the calculations was also the selection of meteorological, demographic, nutritional and agricultural data. Meteorological data over a period of one year was used for the probabilistic calculations. Deterministic scenarios were selected to be as close as possible to other studies performed in the frame of ITER. Results of the assessments were early and chronic doses which have been evaluated for the Most Exposed Individual at particular distance bands from the release point.
Of particular importance was the comparison between the regulatory and the advanced assessment models. Regulatory models for tritium are sometimes simplistic and are either too conservative or do not consider important processes which might lead to underestimation of the dose. This is for example the case with organically bound tritium which is often not considered in regulatory models but may dominate the dose from ingestion pathways. Therefore, this comparison provided the opportunity to evaluate the appropriateness of a national accepted tool. As the site of ITER was still to be defined, such a comparison was vital and might be also necessary for any other site to assure public confidence in the licensing procedure.