Decommissioning difficulties ahead

February 6, 2017

Editorial: Video shows difficulty in decommissioning Fukushima nuke plant

http://mainichi.jp/english/articles/20170206/p2a/00m/0na/023000c

Video footage of the inside of the No. 2 reactor at the Fukushima No. 1 Nuclear Power Plant has proved that it is more difficult than initially believed to decommission the tsunami-ravaged plant.

• 【Related】Radiation level at Fukushima reactor highest since 2011 disaster; grating hole found
• 【Related】Radiation in Fukushima reactor containment vessel at deadly level: TEPCO
• 【Related】Footage points to difficulty in removing possible melted fuel at Fukushima plant

The camera that was inserted into an area below the reactor's pressure vessel shows a deposited substance near a foothold in the area. The substance is highly likely to be melted nuclear fuel.

Nearly six years have passed since the March 2011 Great East Japan Earthquake and tsunami that triggered the nuclear crisis. The fact that the condition of the inside of the reactor has been confirmed represents a step forward. However, analysis conducted by Tokyo Electric Power Co. (TEPCO), the operator of the crippled power station, shows that the levels of radiation in the reactor building are so high that someone would die within less than a minute if they were exposed to radiation inside the facility. The footage shows that the deposited substances are scattered around in a wide area of the structure. TEPCO had planned to introduce a robot equipped with a camera into the reactor building possibly by the end of this month to fully probe the condition inside, but the footage has forced the utility to reconsider the plan.

If the situation is left as it is, the time required to decommission and dismantle the power station, which is believed to take 30 to 40 years, could be prolonged and the estimated costs of decommissioning the plant, which has already been revised upward from the initial 2 trillion yen to 8 trillion yen, could further rise. TEPCO is required to foot the costs of decommissioning the Fukushima plant, but the expenses will be passed on to consumers who pay electric power charges.

The government and TEPCO should fundamentally review their responses to the nuclear disaster, such as the development of technologies necessary to decommission the plant and ways to reduce decommissioning costs.

Meltdowns occurred in the cores of the No. 1 to 3 reactors at the Fukushima No. 1 Nuclear Power Plant in the accident. According to the road map toward decommissioning the plant, drawn up by the government and TEPCO, the utility is supposed to determine a method to remove melted fuel at one of the reactors by the end of fiscal 2018 and begin work within 2021.

To do so, it is necessary to ascertain where and how deposits of melted fuel are scattered, but this remains unclear.

TEPCO hit a snag at the beginning of the recent survey on the No. 2 reactor. Still, the condition of the reactor is far better than those of the No. 1 and 3 reactors -- which were badly damaged in hydrogen explosions, obstructing surveys of their interiors.

Reactor core meltdowns occurred in an accident at a nuclear plant on Three Mile Island in the United States in 1979. Work to remove melted fuel commenced six years after the outbreak of the disaster and was completed 11 years after the accident. Workers remotely controlled a device to remove melted fuel from the pressure vessel while filling the vessel with water to block radiation.

Work at the Fukushima plant is far more difficult than at the Three Mile power station because nuclear fuel has melted and leaked out of the pressure vessels of the No. 1 to 3 reactors. How and where the melted fuel will be stored has not been decided yet. The government and TEPCO should obtain knowledge both from Japan and overseas to develop technologies to store melted fuel.

In considering the road map toward decommissioning the plant, it should be kept in mind that the degree of progress in the work will affect the restoration of areas hit by the nuclear disaster and the prospects for evacuated residents to return to their homes. However, if an unreasonably tight schedule is created, it could increase the risks of worker accidents and exposure to radiation.

Although it is a difficult task, the government and TEPCO are required to ensure transparency and steadily overcome obstacles to decommission the crippled power station.