Japanese engineers, exhausted after a 50-hour struggle to avert full meltdown at some of the country’s nuclear power plants, resorted yesterday to pumping seawater into a series of perilously overheated reactors in a desperate effort to bring them under control.
The strategy, which may continue for days, comes amid warnings that even the operators at some of the afflicted plants may be unable to gauge how the situation is developing from minute to minute.
The decision to pump seawater mixed with boron into two reactors after cooling system failures at the Fukushima plant, where an explosion on Saturday ripped the roof off part of the complex, was described by nuclear industry experts as being “definitely in the last-ditch category”.
The decision was taken as it emerged that more than 160 people in the area around the plant were in hospital for suspected radiation exposure. In case of further contamination, the Government scrambled to move more than 180,000 people from a 12-mile (20km) exclusion zone.
While the World Health Organisation said that the public health risk from the damaged plants remained fairly low, embassies of several countries, including France, advised their citizens to consider leaving Tokyo for a few days because of the risk that the nuclear crisis might deepen and the wind carry a “radioactive cloud” towards the capital.
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The escalating scale of the crisis sparked international calls for reviews of the global nuclear power industry. Austria’s Environment Minister urged Europe to conduct a “stress test” of its nuclear power plants, and Joe Lieberman, the chairman of the US Homeland Security Committee, said that America should “put the brakes on” building new nuclear plants.
The deterioration of the situation in Fukushima came as the International Atomic Energy Agency declared a state of emergency — the lowest on its sliding scale — at the Onagawa nuclear plant 75 miles to the north after raised levels of radiation were detected, although the plant’s operators claimed that this was because radioactive material had been carried by wind from Fukushima after Saturday’s hydrogen explosion.
A further emergency was declared at Japan’s Tokai No 2 nuclear power plant, 75 miles from Tokyo, after a cooling system failed. But officials said an additional pump was working and was cooling the reactor.
Atomic energy experts described the seawater ploy as both unprecedented and a clear sign that Japan’s battle to win back control over its nuclear plants was far from complete.
Peter Bradford, who served on the US Nuclear Regulatory Commission at the time of the 1979 Three Mile Island disaster in Pennsylvania, said it was still not clear whether the seawater injection strategy was part of existing emergency planning or whether Japanese technicians were improvising.
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Drawing on his experience of the partial meltdown at Three Mile Island, Professor Bradford warned that there could be discrepancies between what the Tokyo Electric Power Company was telling the public and what was actually going on at the plant, most likely because even its engineers did not have full information.
“In hindsight [more than a year after Three Mile Island] we realised that what we knew on day three — in other words where the Japanese are today — turned out to be very different from what had actually occurred in many different ways. One of the issues, which remains uncertain to this day, was how much radiation was released and the significance of those releases,” he said.
Last night, Japanese authorities said a complete meltdown — where all temperature control is lost by engineers, risking the large-scale release of radioactive material into the environment — at Fukushima was unlikely.
However, that assurance offered little comfort as Japanese television relayed worsening news throughout the day. Yukio Edano, the Chief Cabinet Secretary, warned that an explosion of similar ferocity to the one that blew the roof off the building housing Fukushima’s No 1 reactor was a possibility.
Katsuhiko Ishibashi, one of Japan’s foremost seismologists, told The Times that the idea that nuclear plants were well prepared was a “total myth”.
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He said: “When the guidelines for nuclear power plant quake preparations were revised in 2006, I begged the Government to include stipulations about preparing for the aftershocks, but it just refused and preferred to assume that if a plant made it past the initial jolt it would be fine.”