Walls at old reactor found substandard

Kyodo News

The Japan Atomic Energy Agency announced Saturday it has found that concrete walls in a key building at the defunct Fugen nuclear reactor plant in Fukui Prefecture do not meet design standards at 25 of the 34 locations examined.

“We strictly oversaw the execution of construction and it is difficult to believe such a result came out,” an agency official said, adding that the agency will have the strength of the walls checked again.

“The accuracy of the measurements is in question,” the official said.

The agency subcontracted a company to conduct the examination of the auxiliary building that houses the central control room and emergency reactor core cooling facilities.

The building is adjacent to the unit containing the reactor.

The contracted firm does not specialize in inspections, the agency said. A specialist company is expected to conduct the next round of tests.

An official at the Ministry of Economy, Trade and Industry, which is in charge of nuclear policy, said there are no problems with the strength of concrete walls at other nuclear plants.

“We inspected the strength of concrete at 12 old nuclear plants shortly before they had reached 30 years of operations, and examination results and data on documents all matched,” said Hisanori Nei, director of METI’s nuclear power inspection division.

He said METI instructed the agency to report promptly how it arrived at the latest measurements at the Fugen plant.

Located in the city of Tsuruga, Fugen was a new type of reactor developed independently by Japan. Unlike a regular reactor that uses enriched uranium for fuel, Fugen was designed to be capable of running on various kinds of fuel, such as natural uranium and plutonium-uranium mixed oxide fuel.

It reached criticality in 1978. The government in 1995 dropped a plan to build a successor reactor because of high operation costs. Fugen was shut down in 2003 and work is under way to dismantle it.

According to the agency, an inspection to examine wear after nearly 25 years of operations was conducted on walls by removing cylindrical columns with a 10-cm diameter at 34 locations.

The strength of the concrete was lower than the 22.06 newtons, a standard measurement, required by the building’s design at 25 spots. At least at one location, the strength measured 10.6 newtons.