As officials conceded that radiation levels had risen inside one damaged reactor at the Fukushima Daiichi power station, there were fears of a leak with reports that the authorities were planning to release radioactive vapour to ease pressure on the reactor.
Troops trained to deal with nuclear, biological and chemical disasters were deployed to the plant, while US Air Force planes were dispatched to deliver coolant to try to control a rise in the temperature of the facility's nuclear rods.
An eighth of the world's nuclear power reactors are in Japan, and yesterday three plants were reported to have received some damage after the 8.9 earthquake ravaged parts of the country.
A fifth of the country's nuclear power-generating capacity was closed down. The most serious problem was at the Fukushima No 1 reactor; a fire broke out at another plant and a third was said to be leaking water.
Yesterday almost 3,000 residents in Onahama City were ordered to evacuate as Tokyo Electric Power Co (Tepco) confirmed that pressure inside a reactor at Fukushima had risen after a cooling system was knocked out by the earthquake. By late yesterday, radiation levels were increasing within the turbine building and the pressure had risen to 1.5 times its designed capacity. The company said it had been trying to restore its emergency power system so it could reverse the falling water levels inside the reactors and avert the exposure of nuclear fuel rods.
Last night Japan's nuclear safety agency said it was going to release vapour with a radioactive element to ease the pressure but insisted it would not affect humans or the environment.
Everyone within a two-mile radius of the plant, 170 miles north-east of Tokyo, was told to leave the area after a state of emergency was declared at a nuclear power plant for the first time in Japan. Japan's chief cabinet secretary Yukio Edano insisted that the alert was a matter of precaution.
Experts said there could be radiation leakage if water levels in the reactor fell and the temperature of the nuclear rods rose, but warned against panic.
“Even if fuel rods are exposed, it does not mean they would start melting right away,” Tomoko Murakami, leader of the nuclear energy group at Japan's Institute of Energy Economics told Reuters. “Even if fuel rods melt and the pressure inside the reactor builds up, radiation would not leak as long as the reactor container functions well.”
COMMENT RULES: Comments that are judged to be defamatory, abusive or in bad taste are not acceptable and contributors who consistently fall below certain criteria will be permanently blacklisted. The moderator will not enter into debate with individual contributors and the moderator’s decision is final. It is Belfast Telegraph policy to close comments on court cases, tribunals and active legal investigations. We may also close comments on articles which are being targeted for abuse. Problems with commenting? firstname.lastname@example.org