Intercomparison of the tritium concentration prediction models

The most of tritium released from the nuclear power plants to environment is HTO as a vapour, which is entered to the plants by primarily photosynthesis. Some of the HTO entered plants can be incorporated into organic compounds and tritium atoms exchange with labile hydrogen atoms attached to oxygen, nitrogen, sulpher compounds to form OBT. However, most of tritium entered plants is tissue free water tritium(TFWT), which is easily removable from the live stocks. To assess the ingestion dose contributed from tritium, TFWT and OBT concentration in plants and animal should be evaluated. In this study, tritium concentrations predicted by several models are compared and OBT/TFWT ratio is calculated for each plants and animals. As the result of evaluation, rice has more OBT than TFWT, however, lettuce has less OBT than TFWT. Comparison with several models shows that USNRC 1.109 has the least concentration and specific activity model has the greatest. The predicted tritium concentration is ranged from 0.6 times to 1.5 times of average concentration in plants and from 0.2 times to 1.9 times of average concentration in porks