On September 30, 1999, a self-sustaining nuclear accident occurred at a nuclear fuel processing plant in Tokaimura, Ibaraki Prefecture. The shock felt in Japan also reverberated around the globe, for it had been 15 years since the world's last criticality accident. Even several month after the disaster, the accident continues to be a source of grave concern. The cause of the accident is already known, and the problems encountered by the central and local government in reacting to Japan's first criticality accident are evident. However, many questions remain unanswered.

On the international scale used to measure nuclear accidents, which ranks them in severity from 0 to 7, the Tokaimura accident was rated as level 4, according to the Science and Technology Agency. By comparison, the 1986 accident at Chernobyl in the former Soviet Union rated as a level 7, and the 1979 accident at Three Mile Island in the United States ranked as a level 5. Tokaimura was therefore less serious than either of those. However, in reaction to the Chernobyl accident, nuclear safety techniques had supposedly been advancing rapidly. In this context the fact that a nuclear accident could reach critical mass in an industrialized nation came as a grave shock to nuclear experts, not only in Japan but around the world.

Was Human Error to Blame?
Employees of JCO, the company that operates the plant, did not follow the procedures outlined in the plant's instruction manual, and this is what caused the accident. At the plant, enriched uranium is combined with nitric acid to make uranium dioxide. JCO had made an unauthorized, corner-cutting manual in order to reduce costs, but workers at the plant did not even follow this manual and were unlawfully cutting even more corners. This is the basic reason why the criticality accident occurred. However, the background to the accident was that JCO faced fierce competition from nuclear fuel produced overseas. With such a strong element of human error, some hard questions are being asked about the company's operating philosophy.

Dealing with the Accident
The countermeasures taken after the accident by the central government and the local Ibaraki prefectural administration were certainly not swift enough to cope with the severity of the situation. Why? First, hardly anyone believed that a criticality accident could occur in Japan. Second, communication from the Science and Technology Agency to the Cabinet Office for National Security Affairs and Crisis Management was far too slow. Third, there was not a single nuclear power specialist present to advise the cabinet office members, making it difficult for them to take quick, well-informed decisions. Even in the Ibaraki prefectural government, which was supposed to oversee the Tokaimura plant, the prevailing attitude was that such an accident simply could not happen.

The central government did, however, respond speedily to international concern about the accident by welcoming investigation teams from the International Atomic Energy Agency and the U.S. Department of Energy to ensure that a full and transparent investigation of the accident was carried out.

In trying to learn from this accident, the government as well as local administrations that oversee nuclear facilities are working on systems that would produce swifter action and better decision making in the event of future accidents. As soon as the accident occurred on September 30, the Science and Technology Agency posted updates on its Website in both Japanese and English. There have been calls for the contents of such postings to be more detailed and open in the future, and indeed the agency itself is planning moves in that direction.

The Victims
Sixty-nine people were diagnosed as having been exposed to radiation, three of them workers at the JCO plant. On December 21 one of the workers, who had sustained critical injuries, died of multiple organ failure. The remaining victims are still receiving treatment. There are also many residents near the plant who are worried about just how much radiation they were exposed to.

Consumers are unsure of the safety of produce from the land and waters around Tokaimura, leading to a drop in demand and a fall in prices that has hurt producers. Preliminary findings suggest that producers of dried sweet potato have suffered losses of about 700 million yen (6.7 million dollars at 105 yen to the dollar), and makers of products from young sardines have lost around 600 million yen (5.7 million dollars), although not all affected producers have submitted figures for their losses. The local tourist industry has also been hit hard as visitors stay away. Compensation claims are expected to take quite some time to process, but to meet the immediate needs of those who suffered losses, JCO has agreed with the Ibaraki prefectural government to pay half the claimed damages as a temporary measure by the end of 1999.

Edited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.

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