(June 3, 1994) Under heavy criticism from a U.S.-based group, Japanese officials reluctantly admitted on May 10, that the Tokai-Mura reprocessing plant had found 154 pounds of plutonium previously not accounted for (see related story WISE NC 412.4085).
(413.4094) WISE Amsterdam - Officials at the Science and Technology Agency, which oversees the nation's nuclear programs, confirmed the nuclear material had accumulated as dust inside 17 glove boxes in the fuel production line.
"We never expected so much plutonium would remain stuck in the production line," said Hironori Nakano, a spokesman for the government-funded Power Reactor and Nuclear Fuel Development Corp., which operates the plant.
Activists against nuclear proliferation said the discrepancy raised serious doubts about the safeguards enforced at Japanese nuclear plants, and raised the possibility of terrorists obtaining material to make nuclear weapons. The Washington based Nuclear Control Institute says the material is "presently unaccounted for". But Japanese officials insist the whereabouts of the Pu is known and that volumes of Pu residue were verified by IAEA inspectors in April, during a routine monthly inspection.
"The discrepancy is so big that we have to doubt Japan's nuclear controls," said Jinzaburo Takagi, a nuclear physicist who heads the anti-nuclear Citizens' Nuclear Information Center in Tokyo. "North Korea is attacked for its suspected possession of lesser amounts of plutonium," he said. "Why can Japan get away with this'?"
Officials admitted they had known about the problem since 1988 and that accumulation of the extra plutonium had soared in the last year. They did not report the discrepancy in their records of the total amount of plutonium at the plant until the Nuclear Control Institute raised the question.
The NCI obtained information about the 70 kilograms of unaccounted-for plutonium from the International Atomic Energy Agency.
Ikukawa, of the science agency, said the plant already had begun replacing some of the 17 glove boxes, used to process powdered plutonium, with im-proved ones. Replacing one box costs tens of millions of dollars, he said. "We never intended to hide the discrepancy," said another agency official. Asai said the amount of extra plutonium "hold up" inside the boxes could not be predicted because of a lack of previous experience. Official error margin of the assessment system, developed to measure the amount of Pu "hold up" in the glove boxes is 10%, hut some engineers said it could be as high as 15%. Initially each glove boxe was expected to hold up 1.5 kg Pu, but in three of the 17 boxes 43 kg plutonium is found. The boxes measure 3 to 5 meters wide, I to 2 meters long and about 3 meters high.
Sources:
- Nucleonics Week, 12 May, 1994
- Greenbase, 10 May 1994.
Contact: Citizen's Nuclear Information Centre, 302 Daini Take Bldg. 1-59-14 Higashi-nakano, nakano-ku, Tokyo 164, Japan. Tel: +81 3 5330 9520; Fax: +81 3 5330 9530