TOKYO -- Under pressure from plant management, nuclear plant workers skipped critical safety steps in order to increase the production of uranium fuel, resulting in an accident that ranks as the worst in this country's atomic energy history, according to a Japanese news report yesterday.
The report, carried by Asahi Shimbun, the country's most influential newspaper, and attributed to police investigators, contradicts assertions by officials of JCO Co., a subsidiary of Sumitomo Metal Mining Co. and the operator of the plant, that they had not encouraged the use of production shortcuts.
As a regional police force announced a large-scale investigation into an accident that critically injured three of the workers who were handling the uranium and exposed 52 other people to radiation, the report seemed to indicate that there would be a shift in the probe. The first reports had seemed to blame negligence by the workers rather than a more systematic, company-driven violation of procedures.
Police have indicated that they will pursue criminal charges against plant operators. And the chairman of Japan's Nuclear Safety Commission, Kazuo Sato, announced on national television yesterday that his agency would investigate whether there was "lax supervision by the central government."
According to Asahi Shimbun, police investigators said that "there seemed to be a complication within the company that forced the employees to hasten the production of nuclear fuel" at the Tokaimura plant. Under normal circumstances, the factory produces 0.77 tons of purified, highly enriched uranium trioxide powder a day.
If borne out, this report adds devastating detail to a picture of a plant out of control. When the accident occurred Thursday, the workers were not only pouring uranium fuel from steel buckets with their hands, rather than with the measuring machines ordinarily used, but were using more than three times the appropriate concentration of the radioactive material.
The workers are also known to have mixed more than 35 pounds of uranium fuel into a nitric acid solution, rather than the 5.2 pounds indicated under the factory's normal technique. It was this excess of uranium that triggered a chain reaction involving the fission of deadly nuclear materials.
The newspaper Yomiuri Shimbun reported yesterday that plant officials had said that the accident occurred after procedures had been ignored for a second consecutive day, suggesting a broader pattern of procedural infractions.
The president of Sumitomo Metal was quoted by the newspaper Mainichi Shimbun on Saturday as saying, "We never told JCO to increase fuel production."
Similarly, officials of JCO, the plant operator, said that the accident was a result of the "lack of sufficient expertise" of workers. They have denied telling workers to use shortcuts to increase production. But company officials have acknowledged that the plant has recently faced intense foreign competition, notably from Siemens AG of Germany, to supply fuel to Japan's nuclear power plants.
At the time of the accident, the Tokaimura plant was producing fuel for Japan's controversial Joyo experimental fast-breeder nuclear reactor.
Despite accidents, technical setbacks and international expressions of concern about safety and nuclear proliferation, Japan has been pursuing development of fast-breeder technology for three decades.
The fast-breeder reactors, a sort of unproven nuclear Holy Grail abandoned for cost and safety reasons by most advanced industrial nations, offer the promise of producing more plutonium than they consume, through processes that convert uranium fuel into fissionable plutonium.
Plutonium is the raw material used in most nuclear weapons. Even though Japan has forsworn nuclear weapons, its neighbors -- many of which were victims of its military expansionism -- have often expressed opposition to its handling of plutonium technology that lends itself to weapons-building.
The Tokaimura plant, which was completed in 1973 and began commercial operations nine years later, is the second Japanese uranium-reprocessing plant intended to supply fast-breeder reactors to suffer a serious accident. The other plant, in the same town, suffered a fire and explosion in 1997 that contaminated 35 workers with radiation.
Pub Date: 10/04/99