Japan starts using MOX fuel

05 November 2009

Unit 3 of the Genkai nuclear power plant was scheduled to be restarted today having been partly loaded with mixed-oxide (MOX) fuel assemblies, owner Kyushu Electric Power Co announced. The move marks the first ever use of the fuel in Japan.


Genkai (Kyushu)
Genkai - The first Japanese plant to use MOX fuel (Image: Kyushu)
Kyushu began loading MOX fuel at Genkai 3 on 15 October. The operation had been slated to start on 3 October, but was delayed after an objection from the local parliament. The loading of the MOX fuel was completed on 18 October. The company replaced about one-third of the 193 fuel assemblies in Genkai 3 during the current scheduled refuelling outage, 16 of which comprise MOX fuel.


 Plant owner Kyushu Electric Power Company signed a contract with Mitsubishi Heavy Industries (MHI) in September 2006 for the supply of MOX fuel for Genkai unit 3 - a 1127 MWe pressurized water reactor that began operating in 1994. MHI then subcontracted the manufacture of the fuel to France's Areva, which made the fuel at its Melox plant. Genkai took delivery of the first 16 MOX assemblies in May this year and plans to increase the number in use to 48 of the total of 193 assemblies in the core. Production of a further 20 MOX assemblies began at the Melox plant in early June.


Extending operating lives


Kansai Electric Power Co is seeking to extend the operating life of Mihama 1, which has been in operation for 39 years.


The company has formulated a long-term maintenance strategy for the continued operation of the unit, Japan's second-oldest operating power reactor. It has submitted a request with the Ministry of Economy, Trade and Industry for permission to continue operating the 340 MWe pressurized water reactor beyond its original planned shut down in November 2010.


Under Japanese law, operators of nuclear power plants over 30 years old need to gain government permission every ten years in order to continue operating the plant. So far, only Japan's oldest operating unit - Japan Atomic Power Co's Tsuruga 1, which started up in March 1970 - has been given permission to operate begond 40 years. In September, approval came for the reactor to continue operating until 2016, six years beyond its originally scheduled shutdown, due to delays in the construction of two new units at the site.

About 5% of the content of MOX fuel is plutonium recovered from nuclear fuel already used in power-generating reactors. Recycling the material in this way increases the energy it produces by 12%, while if unfissioned uranium is also recovered and reused the figure increases to 22%. The process also allows the separation of the most highly radioactive fission products, meaning the volume of the most dangerous waste is reduced by over 60%.



This kind of recycling is to be the basis of Japan's future nuclear fuel cycle, so that the resource-poor but energy-hungry country can get the best value from imported uranium. Later steps are planned to include fast neutron reactors to use more plutonium and generate more fissionable fuel with nuclear power providing over 40% of electricity.


Up until 1998, Japan sent the bulk of its used fuel to plants in France and the UK for reprocessing and MOX fabrication. However, since 1999 it has been storing used fuel in anticipation of full-scale operation of its own reprocessing and MOX fabrication facilities.


Preparations are also under way by Shikoku Electric Power Co and Chubu Electric Power Co to introduce MOX fuel into their reactors in or after 2010.


In June, Japan's Federation of Electric Power Companies (Fepco) announced the country's plans for MOX fuel use had been revised. Fepco chairman Shosuke Mori said that, after reviewing the organisation's so-called 'Pluthermal' project in the light of national policy and the availability of the country's own reprocessing facilities, it had been decided to revise its goal of having 16-18 reactors using MOX fuel to fiscal 2015 instead of 2010.


According to a timetable released by Kyushu, Genkai unit 3 was set to be restarted and to reach criticality today. The reactor is scheduled to resume electricity production on 9 November. Power will then be gradually increased, with the unit expected to reach full capacity by 2 December. Performance during the restart using the MOX fuel is to be inspected by the Ministry of Economy, Trade and Industry. Kyushu said that the restart schedule could change as the inspection process progresses.