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| Experts fear Japan reactor’s strength is failing — Findings triggered immediate concern — “I just don’t understand yet why the transition temperature is so high” says NISA panel expert | |
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| Tweet Topic Started: 29 Jul 2012, 12:47 AM (50 Views) | |
| skibboy | 29 Jul 2012, 12:47 AM Post #1 |
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Experts fear Japan reactor’s strength is failing — Findings triggered immediate concern — “I just don’t understand yet why the transition temperature is so high” says NISA panel expert NISA dismisses fears over failing Genkai reactor strength [...] During a meeting in Tokyo that heard experts’ opinions, NISA dismissed all concerns raised over the safety of the No. 1 reactor pressure vessel [at the Genkai nuclear plant in Saga Prefecture] and virtually slammed the door shut to further discussions on the matter. [...] The pressure vessel is the heart of a nuclear reactor. Because it is constantly bombarded by neutron irradiation from nuclear fuel, it eventually loses strength. [...] a metal sample taken out in 1993 showed 56 degrees. But a sample tested in 2009 registered 98 degrees, or 14 degrees above the projected value. The finding triggered immediate concern among experts. NISA has convened an expert panel on 18 occasions since November to determine if rapid cooling of the nuclear reactor in the event of an accident would destroy the pressure vessel. [...] neither Kyushu Electric nor NISA was able to offer a convincing explanation for the abnormal high transition temperature. “You can’t call (the pressure vessel) safe when the cause (of the sharp rise in the transition temperature) remains unknown,” said one expert during the meeting. [...] Hiromitsu Ino, member of NISA’s expert panel and a professor emeritus of metal materials science at the University of Tokyo “I just don’t understand yet why the transition temperature is so high” “I have doubts about the (pressure vessel’s) safety” “The No. 1 reactor should not be put back in operation” Check again in 2025 ‘or so’ NISA has no plans to hold more expert meetings on the issue before it compiles a formal report NISA ended up endorsing Kyushu Electric’s argument that the pressure vessel would not likely crack even if the reactor remained in operation for 60 years. The samples were inspected only by institutions with close ties to the power industry [...] A member of the expert panel proposed that test samples be provided to university-based researchers for more in-depth analysis. But Kyushu Electric and NISA dismissed the suggestion. Kyushu Electric took metal test samples out of the pressure vessel on four previous occasions, it has since discarded the samples extracted on the first and second tests. Another member called for additional tests of the samples that still lie in the nuclear reactor, but the proposal was rejected outright. “We will extract the next sample in 2025 or so,” a Kyushu Electric representative said. Published: July 28th, 2012 By ENENews
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3:16 PM Jul 11