Decommissioning of Fukushima Nuclear Power Plant: Devise Ways to Proceed with Extremely Difficult Work

Editorial

15:53 JST, March 13, 2024

Thirteen years have passed since the accident at the Fukushima No. 1 nuclear power plant of Tokyo Electric Power Company Holdings, Inc. Decommissioning work has not progressed as expected. The government and TEPCO have no choice but to overcome the challenges one by one to break the impasse.

The Fukushima plant lost its power source in the tsunami triggered by the 2011 Great East Japan Earthquake, resulting in the meltdown of the cores of the Nos. 1-3 reactors. Even today, debris of melted nuclear fuel remains untouched in the reactor cores.

The decommissioning of the reactors is targeted for completion in 2041 to 2051. However, due to high radiation levels and the inability of humans to access the site, the details regarding the interiors of the reactors cannot be ascertained, and the method for removing the debris has not yet been determined as well.

The government’s Nuclear Damage Compensation and Decommissioning Facilitation Corporation (NDF) recently compiled a report on the removal of the debris. TEPCO will now begin to consider specific methods based on the policy outlined in the report.

The removal of the debris is the main part of the decommissioning work. The NDF’s report this time can be said to be the first step toward the difficult work that is about to begin.

Currently, a promising idea is to remove the debris exposed in the air using robotic arms or other equipment. If this proves difficult, another way would be to remove the debris by hardening it with cement-based materials.

Because water has the property of shielding radiation, one idea considered was to submerge the entire reactor, thus allowing workers to approach the site. However, as it would be difficult to submerge the entire reactor, the idea was determined to be unfeasible at the current stage.

The only way to proceed is to work with methods that are considered to be feasible at the present time. It is hoped that efforts will also continue to enhance technical capabilities and develop new methods in the future.

One example of the post-accident decommissioning of a nuclear power plant involves the Three Mile Island (TMI) nuclear power plant in the United States that experienced a reactor core meltdown in 1979. The work to remove melted fuel has almost been completed, and the prospect for decommissioning looks good.

In contrast, it is estimated that there are 880 tons of debris at the Fukushima plant, nearly seven times the amount at the TMI plant. Not a single gram of debris has been removed yet, and the degree of difficulty of the work is far higher.

The removal of debris on a trial basis from the Fukushima plant is expected to begin by around October this year. First of all, it is important to make this a success.

Treated water that has been purified from contaminated water has so far been stored in tanks on the premises of the nuclear power plant. The discharge of the treated water into the ocean has begun, and the decommissioning is gradually progressing in some respects.

Once the full-scale removal of the debris begins, it is inevitable that the work will run into even greater obstacles. There will be times in the future when things do not go according to plan. It is essential to be flexible in dealing with the issue and not cling to the original plan.

(From The Yomiuri Shimbun, March 13, 2024)