The failures, which the panel said worsened the extent of the disaster, were outlined in a 500-page interim report detailing Japan’s response to the calamitous events that unfolded at the Fukushima plant after the March 11 earthquake and tsunami knocked out all of the site’s power.

Three of the plant’s six reactors overheated and their fuel melted down, and hydrogen explosions blew the tops off three reactor buildings, leading to a major leak of radiation at levels not seen since Chernobyl in 1986.

The panel attacked the use of the term “soteigai,” or “unforeseen,” that plant and government officials used both to describe the unprecedented scale of the disaster and to explain why they were unable to stop it. Running a nuclear power plant inherently required officials to foresee the unforeseen, said the panel’s chairman, Yotaro Hatamura, a professor emeritus in engineering at the University of Tokyo.

“There was a lot of talk of soteigai, but that only bred perceptions among the public that officials were shirking their responsibilities,” Mr. Hatamura said.

According to the report, a final version of which is due by mid-2012, the authorities grossly underestimated the risks tsunamis posed to the plant. The charges echoed previous criticism made by nuclear critics and acknowledged by the operator of the plant, Tokyo Electric Power.

Tokyo Electric had assumed that no wave would reach more than about 20 feet. The tsunami hit at more than twice that height.

Officials of Japan’s nuclear regulator present at the plant during the quake quickly left the site, and when ordered to return by the government, they proved of little help to workers racing to restore power and find water to cool temperatures at the plant, the report said.

Also, the workers left at Fukushima Daiichi had not been trained to handle multiple failures, and lacked a clear manual to follow, the report said. A communications breakdown meant that workers at the plant had no clear sense of what was happening.

In particular, an erroneous assumption that an emergency cooling system was working led to hours of delay in finding alternative ways to draw cooling water to the plant, the report said. All the while, the system was not working, and the uranium fuel rods at the cores were starting to melt.

And devastatingly, the government failed to make use of data on the radioactive plumes released from the plant to warn local towns and direct evacuations, the report said. The failure allowed entire communities to be exposed to harmful radiation, the report said.

“Authorities failed to think of the disaster response from the perspective of victims,” Mr. Hatamura said.

But the interim report seems to leave ultimate responsibility for the disaster ambiguous. Even if workers had realized that the emergency cooling system was not working, they might not have been able to prevent the meltdowns.

The panel limited itself to suggesting that a quicker response might have mitigated the core damage and lessened the release of radiation into the environment.

“The aim of this panel is not to demand responsibility,” Mr. Hatamura said. He also said the panel’s findings should not affect debate on the safety of Japan’s four dozen other nuclear reactors.

Taro Umemura contributed reporting.

Article source: http://www.nytimes.com/2011/12/27/world/asia/report-condemns-japans-response-to-nuclear-accident.html?partner=rss&emc=rss