Tepco shares slump 10% after regulator slams breaches at nuclear station

By Aaron Sheldrick and Ritsuko Shimizu

TOKYO (Reuters) - Shares of Tokyo Electric Power (Tepco) fell the most in eight years on Wednesday after Japan's atomic regulator found safety breaches at its Kashiwazaki Kariwa station and a government minister said the plant will not restart soon.

Tepco shares had surged in recent months on hopes it would be able to restart Kashiwazaki Kariwa, the world's biggest nuclear power station, after years of trying to convince regulators and local residents it had learnt the lessons of the Fukushima disaster 10n years ago.

Regulators used their most serious evaluation - known as a red evaluation - of Tepco's breaches that included failure to protect nuclear materials.

Also, Tepco's security missteps led to an unauthorized staff member accessing sensitive areas of Kashiwazaki Kariwa last year.

Economy, Trade and Industry Minister Hiroshi Kajiyama told reporters on Tuesday he takes the breaches "seriously" and made it clear that Tepco would not be able to restart the station anytime soon.

"Naturally, we are not at a stage where operations can be resumed," Kajiyama said.

The company took the regulator's findings "very seriously", a Tepco spokesman said.

"Unfortunately, we have experienced a rash of nuclear material protection-related incidents at the Kashiwazaki Kariwa nuclear power station since the unauthorized use of an ID card last year," he said.

President Tomoaki Kobayakawa was summoned to parliament on Wednesday to respond to questions on the issue , the Tepco spokesman said.

Tepco estimates it can save 90 billion yen ($825 million) in fuel costs by getting reactors Nos 6 and 7 restarted. The 1,356 megawatt units have been offline since at least 2012 and are the only ones at the station that have received basic licenses to operate.

Only four reactors are operating in Japan and only nine have been given all the restart approvals necessary under new regulations imposed following Fukushima.

Tepco shares closed 10.2% lower, the biggest daily decline since July 2013, at 354 yen, having risen in recent weeks as hopes built the company would be able to restart a reactor at the mammoth station.

GRAPHIC: Japan nuclear operator shares: https://fingfx.thomsonreuters.com/gfx/ce/dgkpledngvb/Capture.PNG

Toyoshi Fuketa, the chairman of Japan's Nuclear Regulation Authority, said even if the necessary further inspections were carried out quickly they would take more than one year.

The regulator on Wednesday decided to halt its internal processes needed for Tepco to load uranium fuel rods into the station's No.7 reactor, Kyodo reported.

In a preview of the Fukushima disaster a decade ago, an earthquake damaged the Kashiwazaki Kariwa plant in 2007, causing radiation leaks and building mistrust among local communities that need to sign off on any restart.

($1 = 109.1300 yen)

(Reporting by Aaron Sheldrick and Ritsuko Shimizu; Additional reporting by Yuka Obayashi; Editing by Kim Coghill)