Basic principles on the safety evaluation of the HTGR hydrogen production system

Ohashi, Kazutaka*; Nishihara, Tetsuo ; Tazawa, Yujiro; Tachibana, Yukio ; Kunitomi, Kazuhiko 

As HTGR hydrogen production systems, such as HTTR-IS system or GTHTR300C currently being developed by Japan Atomic Energy Agency, consists of nuclear reactor and chemical plant, which are without a precedent in the world, safety design philosophy and regulatory framework should be newly developed. In this report, phenomena to be considered and events to be postulated in the safety evaluation of the HTGR hydrogen production systems were investigated and basic principles to establish acceptance criteria for the explosion and toxic gas release accidents were provided. Especially for the explosion accident, quantitative criteria to the reactor building are proposed with relating sample calculation results. It is necessary to treat abnormal events occurred in the hydrogen production system as external events to the nuclear plant in order to classify the hydrogen production system as no-nuclear facility and basic policy to meet such requirement was also provided.