Outline and implementation status of decommissioning plan of JRR-4

Ishikuro, Yasuhiro ; Nemoto, Tsutomu; Oyama, Koji

JRR-4 had been shifted to decommissioning phase in December 2017 after we received the approval of the decommissioning plan of JRR-4 on June 2017 and the approval of the change of the safety regulations related to it. Decommissioning works are divided two phases and proceeded according to its plan. In the first phase, we perform reactor shutdown, fuel removal and maintenance management, and in the second phase, the dismantling works. JRR-4 was initially installed for the purpose of shielding experiments of the nuclear ship Mutsu, reached its first criticality in 1965, and had been operated for about 45 years until Dec. 2010. However, in consideration of the expenses required for the new regulatory standards implemented after the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Plant accident and aging degradation, the decommissioning of JRR-4 was determined according to the JAEA reform plan in Sep. 2013. This report describes the outline of the decommissioning plan of JRR-4 and the status of its implementation.