Japan Nuclear Fuel Ltd. (JNFL) announced it restarted operations to produce enriched uranium on March 9th, 2012 at the Rokkasho Uranium Enrichment Plant. In December 2010, JNFL had suspended enrichment using older centrifugal separators at the plant. Since 1993 there has been US$ 20 billion invested in the project, nearly triple the original cost estimate. The Rokkasho plant is the successor to a smaller reprocessing plant located in Tōkai, Ibaraki.
“Separative work”—the amount of separation done by an enrichment process— is expressed in units which are so calculated as to be proportional to the total input (energy / machine operation time) and to the mass processed. The same amount of separative work will require different amounts of energy depending on the efficiency of the separation technology. Separative work is measured in Separative work units SWU
Active testing had already been underway at the Rokkasho Reprocessing Plant, but was suspended due to continuing problems with the vitrification furnace for high-level radioactive waste (HLW).
Existing centrifuges in its uranium enrichment business have a total capacity of 1,050-ton SWU/year. JNFL has been carrying out work in two installments to update the 75-ton-SWU/year capacity at RE-2A since March 2010, and the latest action is for the first half (37.5-ton SWU/year). The operation itself will be implemented in two steps.
In Step 1, uranium hexafluoride (UF6) gas generated at the conversion tank will be fed intermittently to the updated centrifuge and exhausted, bypassing the old centrifuge.
In Step 2, uranium gas will be fed intermittently to a cascade system (multiple centrifugal separators linked for efficiency), also done repeatedly to attempt to remove impurities.
JNFL will now work on the second installment (constituting the second half of RE-2A, at another 37.5 tons-SWU per year), aiming to start operation in December of this year. Thereafter, over the course of a decade, it will achieve an enrichment capacity of 1,500 tons-SWU per year.
Since the 1970s local opposition to plans to operate Japan’s first large commercial plutonium plant at Rokkasho have focused on the threat of a large-scale release of radioactivity. During the 1990s anti-nuclear groups in Japan released studies showing the risks of routine operation of the Rokkasho Reprocessing Plant. The facility in full operation is designed to separate as much as 8 tons of plutonium each year from spent reactor fuel from Japan’s domestic nuclear reactors. As of 2006 Japan owned approximately 45 tons of separated plutonium.
At a December 27th press conference, JNFL President Yoshihiko Kawai stressed that construction of the MOX Fuel Plant (JMOX) would be resumed this spring. Referring to ongoing discussions on energy policy, he also underscored the need to get the understanding of Aomori Prefecture residents and hear their views on the nuclear fuel cycle business. Another challenge, he said, was getting international recognition of the right of countries without nuclear weapons to reprocess nuclear fuel.