Delay in retrieving nuclear debris: Take practical, realistic steps toward decommissioning

Editorial

16:06 JST, August 10, 2025

Given the difficult road ahead toward decommissioning the Fukushima No. 1 nuclear power plant, revising the plan at this point seems to be a realistic decision.

Operator Tokyo Electric Power Company Holdings, Inc. has announced that it has significantly delayed the start of the full-scale retrieval of melted nuclear fuel from the plant, originally scheduled for the early 2030s, to between 2037 and 2040.

The retrieval of the debris is the most difficult task in the entire decommissioning process. The total amount of debris is estimated to be 880 tons for the Nos. 1, 2 and 3 reactors at the plant, but only about 1 gram was retrieved during two trial attempts last year and this year.

It has been highlighted once again that safely retrieving debris amid high radiation levels is quite challenging.

In addition, in order to begin the major task of retrieving the debris, it will be necessary to remove adjacent buildings to secure space to work and then, a structure to serve as a work platform must also be constructed above the reactor building. A considerable amount of preparation time will inevitably be required.

TEPCO has set a target of completing the decommissioning by 2051, but once it is believed that the retrieval work can be carried out, it will be necessary to review the plan. The current plan was established amid the confusion following the 2011 Great East Japan Earthquake that triggered the meltdown, and it is only natural for it to be updated as work progresses.

Meanwhile, TEPCO has decided on specific methods for retrieving the debris. Robotic arms or other devices will be inserted into the containment vessel of the No. 3 reactor from above or from the side, and debris will be retrieved by injecting filler material to solidify it as necessary. At this point, this method appears to be the most feasible.

Last year, the Nuclear Damage Compensation and Decommissioning Facilitation Corporation, a specialized government agency, proposed three different methods, including flooding the entire reactor building. However, enclosing the entire reactor with a new structure and filling it with water was deemed to be difficult, and the submersion method was not adopted.

Since water, which is highly effective in blocking radiation, cannot be used, work must be carried out with greater caution in order to minimize the amount of radiation that workers are exposed to.

The analysis of debris extracted on a trial basis revealed that it was more fragile than expected and could be broken by human force. It may be possible to combine existing technologies such as high-pressure water jets and lasers to cut and suction the debris.

TEPCO has recorded an extraordinary loss of ¥903 billion based on the new plan. The total cost of decommissioning is estimated at ¥8 trillion, but there is a possibility that this figure will increase further.

The outlook for restarting TEPCO’s Kashiwazaki-Kariwa nuclear power plant in Niigata Prefecture remains uncertain, and TEPCO is facing a difficult business environment. The company is encouraged to manage its operations with a sense of urgency to fulfill its responsibility for decommissioning the Fukushima plant.

(From The Yomiuri Shimbun, Aug. 10, 2025)