J-Power has announced that the start-up of its Ohma nuclear power plant, currently under construction in Aomori prefecture, northern Japan, has been put back by two-and-a-half years.
|How the Ohma plant could eventually look (Image: J-Power)
Start of construction of the 1383 MWe (gross) Advanced Boiling Water Reactor (ABWR) was originally due in August 2007, but was delayed until May 2008 by more stringent seismic criteria. Commercial operation had previously been expected to begin in March 2012.
However, J-Power has said that "after review of construction plans and schedules, J-Power has set the start of operation of its Ohma nuclear power plant for November 2014." The company did not give a reason for the latest postponement. It said it would inform the Ministry of Economy, Trade and Industry (METI) of the change in revised construction plan, as required by the Nuclear Reactor Regulation Law.
J-Power plans to use all mixed oxide (MOX) uranium and plutonium nuclear fuel in the reactor core of Ohma, which necessitates some design variation from the ABWR standard. Amendments for the different reactive and thermal properties of MOX fuel include a higher-capacity liquid control injection system; additional safety valves to release steam; control rods with enhanced neutron absorption; and automatic fuel inspection devices to reduce radiation exposure to workers.
Apart from the Fugen experimental Advanced Thermal Reactor (ATR), Ohma would be the first Japanese reactor built to run solely on MOX fuel incorporating recycled plutonium. It will be able to consume a quarter of all domestically-produced MOX fuel and hence make a major contribution to Japan's "pluthermal" policy of recycling plutonium recovered from used fuel.
Currently, MOX fuel is produced for Japanese nuclear operators in France and the UK. In future, Japan Nuclear Fuel Ltd (JNFL) will operate a used nuclear fuel reprocessing and recycling complex at Rokkasho which will enable this to be done domestically. The Rokkasho facility is due to start operation this month, following a 28-month test phase plus some delay at the end of 13 years construction. J-Power said that Ohma operating with a full MOX core would use 25% of Rokkasho's annual output.