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MOX Fuel Assemblies for Japan’s Ohma N-Plant

Ohma-J-PowerThe Japan Electric Power Development Co Ltd (J-Power) has signed an agreement with Global Nuclear Fuel Japan (GNF-J) for the supply of mixed-oxide (MOX) fuel assemblies for use in the Ohma nuclear power plant in Aomori Prefecture, Japan.

GNF-J has outsourced the manufacture of the MOX fuel assemblies to Areva’s Melox subsidiary which will fabricate the fuel at Melox’s plant in southern France, using Japanese plutonium recovered during the reprocessing of used fuel at Areva’s La Hague plant.

Construction of the 1383 MWe Advanced Boiling Water Reactor (ABWR) at Ohma began in May 2008. The loading of the MOX fuel is scheduled to start in December 2013, ahead of the plant’s planned start-up in November 2014.

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.

MOX consists of a mix of uranium and plutonium oxides, recovered from used nuclear fuel. More than 30 power reactors in Belgium, France, Germany and Switzerland use MOX fuel, typically as one-third of their cores. Some units can use up to 50 percent MOX and some modern designs could use 100 percent MOX.