Overflow of water of Spent Fuel Storage Pool at Spent Fuel Receiving and Storage Building, Rokkasho Reprocessing Plant (RRP)

At 11:15 pm on December 8, 2025, an earthquake with a seismic intensity of 5-lower* occurred at Rokkasho village.

At 2:34 am on December 9, we confirmed that more than 100 liters of pool water overflowed at the Spent Fuel Receiving and Storage Building of RRP, due to the earthquake.

We started collecting the overflowed pool water at 5:13 am and removed approximately 650 liters by 9:30 am and confirmed that there was no contamination on the floor. The collected pool water will be treated as radioactive waste at the Liquid Waste Treatment Facility.

The overflowed pool water remained on the floor of the Spent Fuel Transferring area and Fuel Storage area of the Spent Fuel Receiving and Storage Building, and did not flow out of the controlled area. The water level of the pool is within the normal range after the earthquake. Exhaust stack radioactivity monitor and monitoring posts readings did not increase, and there were no external effects or safety problems caused by radioactive substances.

We have confirmed that there were no injuries and that there were no effects on the other facilities.

*Earthquake with a magnitude of 7.5 (Epicenter: eastern coast of Aomori Prefecture)