Study on the safety system in the High Temperature Gas Cooled Reactor (Contract research)

Nishihara, Tetsuo ; Muto, Yasushi; Uchida, Shoji*; Yoshioka, Naoki*

JAERI has conducted the feasibility study of the HTGR gas turbine system from 1996 to 2000 sponsored by MEXT. This report concludes the safety criteria and rationalization of the safety items in the HTGR system.With respect to the safety criteria, the same value for the LWR is selected as the limit of radiation exposure. Probability of the design basis event (DBE) and beyond design basis event (BDBE) is set lower than those for the LWR to get higher safety margin. Adequate initial events and mitigation system are selected to consider the event sequence. The concept of the probability analysis is applied to identify DBEs and BDBEs. It is found that some safety items can be rationalized in consideration of the safety features of the HTGR. Finally, the safety class and design category of the items in the HGTR-GT are classified.