Siting evaluation of High Temperature Engineering Test Reactor

It is necessary to evaluate hypothetical accident to judge the appropriateness of reactor siting condition. Hypothetical accident is postulated assuming the occurrence of an accident which is unlikely to occur from a technical standpoint. The safety characteristics and/or advantages of the HTGRs are (1) slow response to core heatup events and (2) high temperature that fuel can sustain before the initiation of fission product release. A double-ended rupture of coaxial double pipe of the primary cooling system was selected as the hypothetical accident of the HTTR. Since the HTTR is a HTGR, the core temperature changes slowly and no instantaneous failure of coated fuel particles occur. Therefore, time-dependent release model was newly introduced to calculate the release amount of core contained fission products during the accident. From the result based on the analytical model developed here, appropriateness of siting condition of the HTTR was confirmed