Reply #30: Tepco detected sharp rise in radiation in reactor 1 immediately after temblor struck [View All]

http://www.bloomberg.com/news/2011-05-19/fukushima-may-have-leaked-radiation-before-quake.html

Japan’s Fukushima Reactor May Have Leaked Radiation Before Tsunami Struck
By Yuji Okada, Tsuyoshi Inajima and Shunichi Ozasa - Thu May 19 10:21:12 GMT 2011

A radiation alarm went off at Tokyo Electric Power Co.’s Fukushima nuclear power plant before the tsunami hit on March 11, suggesting that contrary to earlier assumptions the reactors were damaged by the earthquake that spawned the wall of water.

A monitoring post on the perimeter of the plant about 1.5 kilometers (1 mile) from the No. 1 reactor went off at 3:29 p.m., minutes before the station was overwhelmed by the tsunami that knocked out backup power that kept reactor cooling systems running, according to documents supplied by the company. The monitor was set to go off at high levels of radiation, an official said.

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Officials at the company, known as Tepco, had earlier said the plant stood up to the magnitude-9 quake and was crippled by the tsunami that followed, causing the world’s worst nuclear crisis since Chernobyl in 1986. The early radiation alarm has implications for other reactors in Japan, one of the most earthquake prone countries in the world, because safety upgrades ordered by the government since March 11 have focused on the threat from tsunamis.

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Tepco this week released thousands of pages of documents that highlight the chaos in the early hours of the disaster as workers frantically tried to prevent meltdowns in three of six reactors at Fukushima. They included pictures of whiteboards with scribbled notes of times and events.

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http://search.japantimes.co.jp/cgi-bin/nn20110516a3.html

Monday, May 16, 2011

Tepco detected sharp rise in radiation in reactor 1 immediately after temblor struck
Quake 'hurt reactors before tsunami'
Kyodo

High radiation readings taken in the No. 1 reactor building the night of March 11 suggest it was the quake rather than the loss of cooling that critically damaged the Fukushima No. 1 power plant, a utility source said Saturday.

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Workers entered the No. 1 reactor building during the night to assess the damage only to hear their dosimeter alarms go off a few seconds later, sources at Tokyo Electric Power Co. said. Since they thought the building was filled with highly radioactive steam, the workers decided to evacuate.

Based on the dosimeter readings, the radiation level was about 300 millisieverts per hour, the source said, suggesting that a large amount of radioactive material had already been released from the core.

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The Nuclear and Industrial Safety Agency has so far said the reactor withstood the shaking and that the unexpectedly large tsunami caused a station blackout, which led to explosions.

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