JAPAN | Gov’t nuclear panel noted but downplayed risk of power loss at plants

Posted on July 14, 2011


JAPAN | MAINICHI | 14 July 2011

In this March 12, 2011 image made from video from NTV Japan via APTN, smoke rises from Unit 1 of the Fukushima No. 1 Nuclear Power Plant in Okuma, Fukushima Prefecture. (AP Photo/NTV Japan via APTN)

TOKYO (Kyodo) — Experts in a government commission overseeing the safety of nuclear power generation noted in the early 1990s the possibility of fatal damage to nuclear power plants resulting from loss of all alternating-current sources for long periods, as in the case of the Fukushima Daiichi plant, but played down the risk in view of Japan’s advanced power source technology, commission sources said Wednesday.

A panel of five experts in the Nuclear Safety Commission of Japan held 12 meetings between October 1991 and June 1993 to study cases related to the loss of power sources at nuclear power plants at home and abroad, according to the commission.

Representatives from Tokyo Electric Power Co. and Kansai Electric Power Co. participated in the study project.

In June 1993, the expert panel compiled a 96-page report warning that the loss of power sources for long periods could have grave consequences such as damage to reactor cores, the sources said.

The panel noted that measures to prevent such power losses were taken into account for the safety of nuclear power generation in the United States and France.

But given the absence of cases in Japan and the nation’s advanced power source technology supposedly minimizing the possibility of an atomic power plant losing all alternating-current sources and making it likely it could quickly restore them, the panel concluded in the report that the chances of reactors falling into a fatal situation were low.

In this March 11, 2011 file photo released by Tokyo Electric Power Co., waves of tsunami come toward tanks of heavy oil for the Unit 5 of the Fukushima Dai-ichi nuclear complex in Okuma, Fukushima Prefecture, northeastern Japan. (AP Photo/Tokyo Electric Power Co.)

The panel added that the possible loss of power sources for long period did not need to be taken into consideration for the safety design of nuclear power plants in Japan.

Shigeharu Kato, a senior official at the Cabinet Office who serves at the commission secretariat, said the report will be discussed at a subcommittee meeting in the commission on Friday.

Hit by the magnitude-9.0 earthquake and ensuing tsunami on March 11, Tokyo Electric’s six-reactor nuclear complex in the northeastern Japan prefecture of Fukushima lost nearly all its power sources, leading the cooling functions of the reactors and spent nuclear fuel pools at the Nos. 1 to 4 units to fail.

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