Experiments and validation analyses of HTTR on loss of forced cooling under 30% reactor power

Takamatsu, Kuniyoshi  ; Tochio, Daisuke ; Nakagawa, Shigeaki  ; Takada, Shoji; Yan, X. ; Sawa, Kazuhiro; Sakaba, Nariaki ; Kunitomi, Kazuhiko 

In a safety demonstration test involving a loss of both reactor reactivity control and core cooling, HTGRs such as the HTTR, which is the only HTGR in Japan, demonstrate that the reactor power would stabilize spontaneously. In the test at an initial power of 30%, when the insertion of all control rods was disabled and all gas circulators were tripped to reduce the coolant flow rate to zero, a reactor transient was initiated and examined. The results confirmed that the reactor power would decrease immediately and become effectively zero.