Basic design of high-performance moderator vessel for JRR-3 cold neutron source, 1; Heat evaluation of moderator vessel

Nakamura, Takemi  ; Tokunaga, Sho; Kikuchi, Masanobu

To improve the performance of the JRR-3 cold neutron source, we are developing a high-performance moderator vessel made of A6061. When the helium refrigerator stops and the cooling capacity of the condenser is lost, the supply of liquid hydrogen to the moderator vessel stops, and the temperature of the moderator vessel heated by decay gamma rays increases. The maximum temperature of the vessel must not exceed 100 degrees, because A6061 in the temperature range of 100 degrees or higher has lower mechanical strength and is easy to cause creep. We calculated the heat generation of the high-performance moderator vessel and evaluated the soundness of the vessel by calculating the temporal change in temperature of the vessel after the helium refrigerator was stopped.