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Plan mooted to submerge reactor at Fukushima nuclear plant

Yomiuri Shimbun file photo
The Fukushima No. 1 nuclear power plant is seen on March 17.

The Nuclear Damage Compensation and Decommissioning Facilitation Corp. (NDF) is considering the feasibility of a submersion method for the removal of radioactive debris at Tokyo Electric Power Company Holdings Inc.’s Fukushima No.1 nuclear power plant.

The plan involves using a tank-like structure to encapsulate a reactor building and filling the structure with water to remove debris. As water acts as a shield against radiation, the method would be expected to improve the safety levels of decommissioning work. However, the feasibility of the plan is uncertain given the unprecedented scale and high costs.

NDF, a state-backed organization that provides technical proposals to the government and TEPCO, has compiled a decommissioning strategy every year since 2015. The plan to submerge the reactor will be included in its 2022 strategy report.

Meltdowns occurred in reactors Nos. 1-3 in the nuclear accident triggered by the 2011 earthquake and tsunami that devastated areas across northeastern Japan.

The plan being considered involves submerging the No. 3 reactor building as its containment vessel has the highest water level.

Until recently, TEPCO and NDF had considered filling the containment vessels with water to remove the radioactive debris, but the vessels were damaged in the nuclear accident, and radiation levels around them are so high that it would be difficult to conduct repairs.