Automation of temperature control system for the capsule irradiation of JRR-3

Ushijima, Hiroki; Okada, Yuji ; Mitsui, Kento ; Nakamura, Takemi  ; Inoue, Shuichi 

We are renewing the aging equipment of JRR-3 to irradiate capsules with temperature control. The conventional equipment had to be manually adjusted whenever the capsule temperature fluctuates according to the position change of control rod. Hence, the goal of this renewal is to automate the capsule temperature control from before reactor startup to after shutdown. The new system uses vacuum control and heater control. We performed cold tests to check the performance of the equipment. It was found that the device performed satisfactorily by varying the mock capsule to several temperatures. In addition, reactor power values are captured by the new system. The target temperature in conventional equipment was maintained by feedback of changes in capsule temperature. On the other hand, the new equipment starts in conjunction with the reactor power before the capsule temperature changes, so that we expect improved accuracy in temperature maintenance.