Major fault line found running under nuclear reactor west of Tokyo

December 11, 2012 – TOKYO - A fault running directly underneath the Unit 2 reactor of the Tsuruga plant, operated by Japan Atomic Power Co. and located about 330 kilometers (200 miles) west of Tokyo, “could be an active one,” the panel said in a meeting to review an on-site investigation carried out Dec. 1-2 into faults within the plant’s premises. The government’s top spokesman, Chief Cabinet Secretary Osamu Fujimura, stressed, however, that steps need to be taken before any final decision. “We shouldn’t make any predictions at this stage,” he said. For one, the panel’s assessment needs to be reviewed by the new regulator, the Nuclear Regulatory Commission, and it isn’t known when the commission will meet. Still, NRC Chairman Shunichi Tanaka said the commission won’t be able to consider a request to restart the plant as long as there is a possibility the fault is active. Japan Atomic Power submitted an open letter to the NRC Tuesday asking for clarification of the experts’ views, which it said “are not fully explained and lack scientific basis.” If the commission determines there is an active fault under the unit, the company won’t be allowed to restart it, and might have to decommission it. Japan Atomic Power said the conclusion of the panel was “totally unacceptable.” The company added that “we will conduct additional surveys and prove our position with objective data.” A shutdown isn’t a foregone conclusion, experts say. “All the panel is saying is that the fault could be an active one. That means they are arguing that it is equally possible that the fault is inactive,” said Hiroaki Koide, a nuclear-reactor engineer at Kyoto University. “I suspect there is still a good chance of the reactor getting restarted in the future.” Opened in 1970, the Tsuruga plant is one of the oldest in Japan. The major fault line, the Urazoko fault, was found in 2008 to be running 250 meters (825 feet) from the two reactor buildings. Several smaller faults extending from the main Urazoko fault run directly under Unit 2’s reactor. Despite the discovery of the Urazoko fault, Japan Atomic Power continued to operate the plant, saying the smaller faults wouldn’t move in tandem with the bigger one. Some geologists have argued that the land could shift along these faults if a major earthquake triggers movement along the Urazoko fault. The March 2011 disaster at the Fukushima Daiichi nuclear plant raised fresh concerns, and the regulator has since been reviewing the safety of all of Japan’s 50 reactors. Currently, only two reactors are operating in the country, and those also are under investigation because of concerns over fault lines. The suspension of nuclear reactors has resulted in a sharp decline in Japan’s power-generating capacity. On the northern main island of Hokkaido, the government is calling for voluntary power conservation amid rising demand due to winter weather. Supply concerns are expected to re-emerge when demand peaks again in summer. -WSJ

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