Estimation of pressure change based on hybrid control system in JSNS hydrogen loop

Hasegawa, Shoichi   ; Aso, Tomokazu ; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko*; Sakurayama, Hisashi; Kato, Takashi

In JSNS, supercritical hydrogen is adopted as a moderator material. A heat load of moderators is changed by fluctuation of nuclear heating due to pulsed proton beam. The maximum nuclear heating is estimated to be 3750W at 1MW proton beam. Therefore, a pressure control system should be required for the hydrogen system. A hybrid pressure control system, which consists of a heater and an accumulator, is prepared. The heater compensates a heat load of the nuclear heating, and the accumulator has a variable volume to absorb pressure fluctuation. The design of hybrid pressure control system required the estimation of hydrogen pressure behaves. An original computer code was developed to analyze such pressure behaviors in the various cases of nuclear heating change, for example proton beam on and off. Then the analysis result determined the capacity of the accumulator and the analysis indicated that the pressure change could be controlled within 0.15MPa by the designed hybrid control system.