Japanese reactor cleared for extended operation

05 July 2010

Japanese utility Kansai Electric Power Co (Kepco) has received regulatory approval to operate unit 1 of its Mihama nuclear power plant beyond its originally planned 40-year lifespan. The company also said that it will begin considering replacing the reactor with a new one. 


On 28 June, the Nuclear and Industrial Safety Agency (Nisa) - a unit of the Ministry of Economy, Trade and Industry (Meti) - approved Kepco's long-term policy on maintenance and management at Mihama 1 beyond 40 years.


Kepco submitted its application to extend the operating life of the unit to Meti in November 2009. This included a technical assessment of ageing at the unit and an evaluation of the use of life-extending technologies at the plant, including establishing a long-term policy on maintenance and management. Although Kepco's application was based on an assessment to operate the unit for a further 20 years, the company said that it intends to continue running the reactor for a maximum of ten more years.


In considering its approval of the unit's extended operation, Nisa also took into consideration plant management's assessment of ageing at the reactor after 30 years of operation and the operational performance since then.


Kepco also said it would initiate a study into the possibility of constructing a new reactor at the Mihama site in Fukui prefecture to replace unit 1 when it eventually shuts down.


The 340 MWe pressurised water reactor (PWR) began operating in 1970 and will complete its 40th year of operation in November 2010. Two other PWRs are in operation at Mihama: a 470 MWe capacity unit and a 780 MWe reactor, which started up in July 1972 and December 1976, respectively.


So far, only one other nuclear power reactor in Japan has been authorized to operate beyond 40 years. In September 2009, Meti gave approval to Japan Atomic Power Co (Japco) to continue operating its Tsuruga 1 unit until 2016, six years beyond its originally scheduled shutdown. The extension was due to delays in the construction of two new units at the site.


Researched and written 

by World Nuclear News