A fault running under reactor 2 at the Tsuruga plant in Fukui Prefecture is active, a Nuclear Regulation Authority panel said Wednesday, effectively killing any chance the reactor will be reactivated.
The report by the panel of five experts, including NRA Commissioner Kunihiko Shimazaki, is the first issued on its investigation into active faults at the Tsuruga plant, and deals a heavy blow to its operator, Japan Atomic Power Co.
The NRA will discuss what to do about the Tsuruga reactor at its regular meeting scheduled for next Wednesday.
The panel determined that the fault, a zone of pebbles and sediment called D-1, could shift at the same time as two others: one known as K and the other an active major fault called Urazoko.
The K fault, which appears to have moved within the past 130,000 years, is therefore considered technically active. The report also finds that the D-1 fault is part of this “structure,” and thus is active as well. The active Urazoko fault is located about 200 to 300 meters from the reactor buildings.
Japan Atomic Power has claimed the K fault is inactive based on its analysis of volcanic ash, which it says shows there has been no recent movement. The panel rejected this claim as untrustworthy.
“The panel thinks that the D-1 fault is an active fault, which needs to be taken into consideration in earthquake-resistance planning,” the report said.
Meanwhile, the Tsuruga plant’s reactor 1, which has been in operation for 43 years, is likely to be decommissioned. New safety rules to be implemented in July ban in principle reactors 40 years or older.
Consequently, Japan Atomic Power, which is funded by regional utilities, will have a hard time getting permission to restart its reactors at Tsuruga.
However, if it provides new evidence that the fault is inactive, the NRA may retract its decision, the panel said.
“When new knowledge is found to (prove that the fault is inactive), it is possible that we will review this (evaluation) if necessary,” the report said.
Reactors and equipment critical to safety cannot be built directly over active faults.
Only a week after the panel members inspected the site in December they expressed the opinion that D-1 was probably active.
No go for Monju
The Nuclear Regulation Authority said Wednesday it will effectively prohibit the trouble-plagued Monju prototype fast-breeder nuclear reactor from restarting, at least until its operator remedies its safety management.
“The Japan Atomic Energy Agency cannot sufficiently secure the safety of Monju,” the NRA said in a document, referring to JAEA’s delayed checks on a wide range of Monju’s equipment, reported last November, and subsequent blunders. “We see deterioration in its safety culture.”
Under the order to keep the reactor idled, expected to be issued later this month after necessary procedures are taken, JAEA will be barred from engaging in preparatory work for resuming Monju operations until it overhauls its maintenance and management system for the facility.
A senior NRA official said the order will likely be in place at least until around January because JAEA is not expected to finish the equipment inspections by that time.
Monju, work on which started in 1983, has remained offline for most of the past 20 years because of various problems.
The facility had been expected to play a key role in the country’s nuclear fuel recycling effort.
The reactor first achieved criticality in 1994 but was shut down by a serious sodium coolant leak and fire in 1995 that the operator tried to cover up.
Monju was briefly restarted in May 2010 but, before reaching full output, was halted again when fuel-loading equipment fell into the reactor vessel that August.
Last November, JAEA said it skipped necessary procedures when it delayed planned inspections on nearly 10,000 Monju components, including equipment deemed important for safety.
A JAEA report on the lax checks submitted in January also contained errors.
It has been reported that total costs for the Monju project have run to ¥1 trillion.
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