Source Term Analysis of Tritium in HTR-10

The Very High Temperature Reactor (VHTR) is one of the six proposed Generation IV reactor concepts. The HTR-10, a 10 MW high temperature gas-cooled reactor was a helium cooled, graphite-moderated, and thermal neutron spectrum reactor. Since tritium (H-3) has an effect on the environment and public radiation dose, it has received more and more attention in the environmental impact assessment of nuclear facilities. Recently, several experiments on source terms in HTR-10 have been run, of which preliminary measurements indicated H-3 was an important nuclide in the primary loop of HTR-10. The production mechanism, distribution characteristic, reduction route, and release type of total H-3 in HTR-10 were analyzed and discussed in this technical note. A theoretical model was established to calculate the total activity of H-3 in the reactor core and activity concentration of H-3 in the primary loop of HTR-10. This model indicated that the majority of total H-3 was produced by ternary fission reactions and H-3 in the primary helium was mainly generated from activation reactions of impurities in the reactor core. The research results can provide useful information for the experimental measurement of H-3 in HTR-10, and promote the study of H-3 in high temperature gas-cooled reactors (HTGRs).