Reference material: Japan’s Separated Plutonium Inventory (as of 31 Dec. 2017)
Japan’s stockpiles of separated plutonium stored in France dropped by 731kg in 2017 due to MOX fuel transported from France to Kansai Electric Power Company’s Takahama plant during that year. The stockpiles stored in Britain, on the other hand, increased after the country announced that 393kg of separated plutonium had been allocated to Japan.
Although reprocessing of Japan’s spent nuclear fuel has already been completed at the British reprocessing plant, Britain says that the plutonium allocation rose due to calculations concerning amounts of nuclear materials stipulated in the contract. Plutonium separation and allocation were delayed at the Sellafield reprocessing plant in Britain due to an accident in 2005, in which there was a leak of high-level radioactive materials. It is expected that Britain will announce transfer of the remaining 600kg of plutonium to Japan sometime next year, 2019.