Top government spokesman Osamu Fujimura said in a news conference that the matter will be reported to the IAEA soon, but did not say how much nuclear material was involved.
The chief Cabinet secretary said an investigation last year of records led to the discovery of nuclear substances that were unaccounted for in waste at the Japan Atomic Energy Agency's Oarai Research and Development Center in Ibaraki Prefecture.
The Ministry of Education, Culture, Sports, Science and Technology then conducted a probe in August of nuclear energy facilities subject to the IAEA's safeguard program and also found nuclear substances unaccounted for in facilities other than the agency's.
"Based on investigation so far, most nuclear substances have been properly managed as waste, and from that perspective, there is no problem in safety management," Fujimura said. Read More