The Japanese authorities were trying to cope early this morning with a massive nuclear accident at a uranium processing plant which released large amounts of radioactive material into the environment. Local government officials said the operation to try to stop a possible nuclear chain reaction was progressing slowly.
Early today, a team of experts tried to drain cooling water from the tank to stop the reaction, said a plant official, but a public television report said the effort had failed. Officials were now considering partly destroying some of the pipes to complete the job, it said.
Nuclear experts will check monitors at the site again at 9 a.m. local time to determine whether the self-sustaining chain of nuclear fission has ended.
The incident exposed 55 people to high levels of radiation and three workers were airlifted to hospital. Two of the workers - Mr Hisashi Ouchi (35), and Mr Masato Shinohara (39), - were "barely conscious." They responded to questions but their blood pressure was low. The third injured man, Mr Yutaka Yokokawa (54), walked into hospital and was treated in a normal ward, but doctors later said he was also in a serious condition.
The accident, which happened at a plant in Tokaimura - some 75 miles north-east of Tokyo - was officially described as a "criticality incident" meaning that a nuclear chain reaction had begun and was self-sustaining. The uranium had gone into spontaneous fission, the reaction that occurs during a nuclear explosion.
"There is a strong possibility that abnormal reactions are continuing inside even now," Chief Cabinet Secretary Hiromu Nonaka said early today. "The situation is one our country has never experienced."
Radiation levels 15,000 times above normal were being recorded 1 1/2 miles from the plant. Tokaimura has a population of some 34,000 people and is the centre for 15 nuclear-related facilities. A total of 310,000 people live within a 10km radius of the site and were being urged to remain indoors. Fifty families in the immediate vicinity were evacuated.
This morning the Japanese cabinet was in emergency session and it seems almost certain that a wider evacuation will have to be ordered. Local farmers were told not to harvest crops amid fears that a large area could become unusable as happened around the Chernobyl plant in the Ukraine.
Early today, heavy rain was keeping radiation levels high. "The level of radiation is resisting any decline and the number of neutrons is increasing," said Mr Setsuo Onodera, a nuclear affairs official, at Tokaimura town office near the accident scene.
The unprecedented peacetime emergency was caused by an explosion which blew open a hole in the production building's roof, allowing radioactive gases and dust to escape.
It happened when two workers pumped too much uranium-nitric acid solution into a tank. A spokesman for the company said: "Workers were mixing uranium powders with nitric acid to make a uranium solution. But they pumped too much uranium solution into the tank, causing the nuclear reaction. The operation involved 16kg of uranium." The tank had maximum capacity for 2.4kg.
The extent of the nuclear pollution caused by the accident could be gauged by the fact that measurements of 3.1 millisieverts per hour were taken a mile and a half from the plant. This is equivalent to receiving a typical entire year's dose of natural and man-made radioactivity in a single hour. The maximum annual allowable radiation dose from man-made sources alone is just one milisievert.
