Homecoming hope for thousands as Fukushima reaches ‘cold shutdown’

Japan’s prime minister announced yesterday that the country’s tsunami-damaged nuclear plant has achieved a stable state of “cold shutdown,” a crucial step toward the eventual lifting of evacuation orders and closing of the plant.

Prime minister Yoshihiko Noda’s announcement was intended to show that major progress has been made since the 11 March tsunami that sent three reactors at the Fukushima plant into meltdown in the worst nuclear crisis since Chernobyl in 1986. The tsunami knocked out vital cooling systems, leading to radiation leaks and forcing people to evacuate nearby areas. The crisis displaced some 100,000 people.

Mr Noda said yesterday: “Now that we have achieved stability in the reactors, a major concern for the nation has been resolved.”

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Radiation released from the plant has been substantially reduced, and additional safety measures installed at the plant ensure stability even in the event of another major disaster, he said.

The announcement is a key step towards a situation where evacuation zones around the plant can be revised. That would shift the focus from simply stabilising the facility to starting the arduous process of shutting it down.

The announcement marks the end of the second phase of the government’s lengthy roadmap to completely decommission the plant.

Officials can now start discussing whether to allow some evacuees to return to less- contaminated areas – although a 20km zone around the plant is expected to remain off-limits for years to come.

“We hope this will be a step towards allowing our residents to return home, but the road ahead is long and difficult,” Fukushima governor Yuhei Sato said.

A “cold shutdown” normally means a nuclear reactor’s coolant system is at atmospheric pressure and its reactor core is at a temperature below 100C, making it impossible for a chain reaction to take place. According to the plant’s operators, temperature gauges inside the reactors show the pressure vessel is at about 70C.

The government had pledged to achieve such status by the end of this year, but has also said it will take decades to dismantle the complex completely.

Experts say the plant, 230km north-east of Tokyo, remains vulnerable to problems and its surroundings are contaminated by radiation – and that closing the plant safely will take 30 or more years.

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The complex still faces numerous concerns, triggering criticism that yesterday’s announcement was based on a political decision rather than science.

Nobody knows exactly where and how the melted fuel ended up in each reactor, and the plant is struggling with the vast amount of radioactive water that has collected in the reactor basements and nearby storage areas.

Officials, including nuclear and environment minister Goshi Hosono, admitted the possibility of mechanical glitches, water leaks or other unexpected troubles down the road, but said ample protection was now in place to avert another disaster.

Tokyo Electric Power Company president Toshio Nishizawa apologised for the accident, and vowed to further stabilise the plant and reduce its radiation release until it is finally closed.

Akira Yamaguchi, a nuclear physicist at Osaka University, said the government’s definition of cold shutdown was disputable. “But what’s most important right now is that there aren’t any massive radiation leaks any more,” he said.

Putting longer-term issues aside, he warned that much of the back-up equipment installed at the plant since the crisis began was makeshift and may break down. He said winter cold could test their strength.

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