TEPCO to update maintenance plan for Fukushima Daiichi plant

16 September 2019

Tokyo Electric Power Company Holdings Inc. is set to formulate a new long-term maintenance and management plan for its Fukushima Daiichi nuclear power plant by the end of fiscal 2019 to prevent malfunctions and accidents, as eight and a half years have passed since the Great East Japan Earthquake and ensuing nuclear mishap there. During those years, facilities and equipment for decommissioning and handling of contaminated water have been built one after another on the plant premises. Aging buildings that have not been used since the accident, meanwhile, have been left uncared for and are deteriorating.

According to the utility, its long-term facility check plan, crafted before the disaster, was designed for normal operations. It no longer matches the current post-accident situation, and also does not go into detail about the plant's maintenance. The plan is not a long-term one for maintenance taking into considering the deterioration of aging facilities such as those for decontaminating water in the decommissioning work.

In January this year, a steel plate weighing about 22 kilograms fell from a height of about 76 meters from a scaffolding at the common exhaust stack for Nos. 3 and 4 reactor units of the Fukushima Daiichi plant. The incident, attributed to decrepitude, did not injure anyone, but there was a possibility it could have been much more serious. Against this backdrop, TEPCO judged it necessary to craft a long-term maintenance plan that will run through the completion of the decommissioning work, which is expected to take 30 to 40 years.

In order to draw up the plan, the company will pick out and make a list of facilities among all those on the plant's premises that may pose a risk of leaking radioactive substances if damaged, as well as instruments for monitoring stability inside reactor containment vessels, structures that may collapse and facilities near working passages. It plans to carry out measures, such as repairing and reinforcing of facilities and equipment, by prioritizing them according to the degree of their importance and danger.

In addition to checking the current condition of the facilities, the company plans to determine when repairs will be necessary by estimating their future deterioration caused by aging, weakening of concrete strength, and deterioration due to heat or radiation. It will also revise the measures and cycles of the current facility checks.

The utility plans to formulate a plan for each of its high-priority facilities by the end of fiscal 2019 on March 31, 2020. Measures for other facilities will be examined in fiscal 2020 or later. After formulating the plans, the company will update them, taking actual on-spot situations into consideration. It will also reduce risks by revising patrol and other monitoring methods as well as their frequency.

TEPCO says, "There are portions that cannot be said to be sufficient under the current maintenance situation. We would like to carry out decommissioning work safely and steadily through appropriate maintenance and management, taking into account deterioration by aging."

The central government's Nuclear Regulation Authority intends to keep watch on TEPCO to make sure measures are carried out under the upcoming new long-term maintenance plan

(Translated by Kyodo News)