The Preliminary analysis of the loss of primary coolant flow test in the HTTR

Nakagawa, Shigeaki  ; Takamatsu, Kuniyoshi  ; Goto, Minoru  ; Takeda, Tetsuaki*; Nakao, Yasuyuki*

Loss of primary coolant flow test is under planning by using the HTTR to demonstrate the inherent safety features during the accident condition such as the depressurization accident which is selected as the severest accident in the HTGR. All the gas circulators are tripped in the test and the position of all control rods keeps its initial one. Because the core temperature increases just after the loss of coolant flow, the reactor power decreases according to coolant flow decrease due to negative reactivity feedback effect and the reactor becomes subcritical. The reactor performance after becoming subcritical during the loss of coolant flow is subject to a reactivity balance of core temperature and xenon concentration changes. The loss of primary coolant flow test in the HTTR simulates the depressurization accident and the data obtained from the test is useful for the validation and improvement of the calculation code applied to the safety analysis in the future HTGR.