Japan fears nuclear plant sits atop active geological fault

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A nuclear plant in northwestern Japan may be sitting right on top of an active geological fault, the country's nuclear watchdog has said, raising the risk that the facility may never resume power generation for fear of an earthquake.

For the first time in more than 40 years, Japan faces the prospect of having no nuclear power within weeks, after last year's crisis at the Fukushima Daiichi nuclear plant crushed public trust in nuclear power and prevented the restart of reactors shut for regular maintenance checks.

The fault fracture zone under the No.1 and No.2 units of the 1,517-megawatt Tsuruga plant could be an active fault that could move jointly with a confirmed nearby active fault, the Nuclear and Industrial Safety Agency (NISA) found in a site survey on Tuesday, a spokesman for the plant's operator said.

The operator, unlisted Japan Atomic Power Co, denies the existence of an active fault right under the plant, citing its geological assessment, but the NISA has ordered an additional investigation following its findings, the spokesman said.

Nuclear power, long advertised as safe and cheap, provided almost 30 percent of Japan's electricity before the crisis, but now all but one of Japan's 54 reactors are off-line, mainly for maintenance. The last reactor will shut down on May 5.

Japan has rules against installing a nuclear plant on top of an active fault that has moved within the last 120,000 to 130,000 years, and the Tsuruga site could be declared unfit to host a nuclear plant.

The plant's 357-MW No.1 unit and the 1,160-MW No.2 unit have been shut since last year for planned maintenance.

Japan Atomic Power had previously aimed to add No.3 and No.4 units at the plant, with capacity of 1,538 MW each, by 2018, but the plan has stalled, reflecting public worries over nuclear power after the Fukushima plant was wrecked in the March 2011 earthquake and tsunami, triggering radiation leaks that caused mass evacuations and widespread contamination.

The restart of the No.1 unit, which began operation in 1970, has been uncertain in light of Japan's plans to limit the life of reactors to 40 years, and permit extensions only under stringent terms. The company had planned to scrap the Tsuruga No.1 unit in 2016.