Report Finds Japan Underestimated Tsunami Danger

TOKYO — Japan underestimated the danger of tsunamis and failed to prepare adequate backup systems at the Fukushima Daiichi nuclear plant, a team of inspectors from an international nuclear regulator said Wednesday in a critical report that was released as the Japanese prime minister prepared to face a no-confidence vote in Parliament.

In its preliminary report on the nuclear crisis, which echoed earlier criticisms of Japan’s inadequate safety measures, the team, from the International Atomic Energy Agency in Vienna, also called for stronger regulatory oversight. Steps should be taken, it said, to ensure that “regulatory independence and clarity of roles are preserved in all circumstances.”

This seemed to repeat a widely held criticism in Japan that collusive ties between regulators and industry led to weak oversight and a failure to ensure adequate safety levels at the plant.

The report did offer some praise, particularly to Japanese plant workers for braving dangerous conditions to try to bring the stricken plant under control. But it did not address some of the main criticisms of Japan’s handling of the crisis, including initially understating the extent of the damage, and slow decision-making that worsened the plant’s problems.

In contrast to its role as watchdog against proliferation of nuclear weapons in countries like Iran, the atomic agency operates narrowly in any civilian crisis, as an adviser that is invited in by the nation’s government to offer nonbinding recommendations on improving safety. 

Still, the report’s cautious criticisms gained attention in Japan, coming on the same day as opposition parties submitted a no-confidence motion against Prime Minister Naoto Kan.

While Mr. Kan is expected to survive the measure, which will probably be voted on in Parliament on Thursday, it has reinforced criticism here that he has been slow and indecisive in his response to the March 11 earthquake and tsunami, which left more than 24,000 people dead or missing. The motion has already proved politically bruising, as a small number of disgruntled members of his own Democratic Party, led by the fallen party kingmaker Ichiro Ozawa, have vowed to join the opposition in voting against Mr. Kan.

“What is most sought by the people is for us to work together to achieve reconstruction and resolve the nuclear crisis,” Mr. Kan said during the heated debate in which opposition leaders demanded his resignation. “I must respond to their needs, and that is my responsibility.”

The report on Wednesday followed a weeklong inspection by the multinational team. Most of the problems that it cited had already been well documented.

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The team said it visited three nuclear plants damaged by the earthquake and tsunami, including Fukushima Daiichi. It said it released the three-page preliminary report to provide quick feedback to the Japanese government as well as lessons to the global nuclear industry. It said it would release a longer version before a nuclear safety conference that starts June 20 in Vienna.

Goshi Hosono, an adviser to the prime minister who serves as Japan’s point man on nuclear issues, said Tokyo accepted the team’s findings. He also said Japan would review its nuclear regulatory framework.

The report spoke highly of Japan’s handling of the crisis once it happened, calling the efforts of workers to regain control of the crippled reactors “exemplary.”

The report also praised steps taken by Tokyo to protect the population from radiation, calling its evacuations of surrounding areas “impressive and extremely well organized.”

Its strongest criticism was aimed at the failure to build adequate protection against large waves for the plant, which sits on Japan’s tsunami-prone northeastern coastline. While the plant was designed to withstand waves of about 19 feet, the tsunami was as high as 46 feet, the report said.

“The tsunami reached areas deep within the units, causing the loss of all power sources except one emergency diesel generator,” the report said, adding that a blackout of the commercial power grid left the plant with “little hope of outside assistance.”

It also said the disaster exposed the lack of varied and redundant backup systems at the plant. The tsunami, which struck 46 minutes after the magnitude-9.0 earthquake, destroyed the emergency diesel generators at four of the plant’s six reactors. This left them with no other power source beyond batteries, which lasted only a few hours.

Once power was lost, critical functions like the cooling system shut down, as did the instruments that told workers what was happening inside the reactors. Three of the reactors quickly overheated, causing meltdowns that eventually led to explosions, which hurled large amounts of radioactive material into the air.

The single surviving diesel generator allowed workers to maintain the cooling systems for the No. 5 and No. 6 reactors, which did not melt down. The No. 4 reactor had already been safely shut down when the earthquake hit, but its cooling pool was damaged by the tsunami.

“The operators were faced with a catastrophic, unprecedented emergency scenario with no power, reactor control or instrumentation,” the report said. The tsunami also “severely affected communications systems both within and external to the site.”

“They had to work in darkness with almost no instrumentation and control systems,” the report said of plant workers.