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Restart of Sendai 1


The Sendai 1 reactor in Japan restarted on 11 August 2015 and re-entered commercial operation in early September 2015. 

Sendai 1 is a pressurized water reactor (PWR) sited on the southwest coast of Kyushu, the third largest island of Japan. It is owned and operated by the Kyushu Electric Power Company.

Sendai 1 has a net electrical capacity of 846 MW, and prior to 2011 produced an average of 6157 GWh (gigawatt hours) of electricity each year. This is enough to meet the electricity needs of 784,000 people in Japan. When operating Sendai 1 avoids the emission of more than six million tonnes of carbon dioxide each year, compared to coal-fired generation.

The shutdown of nuclear generation is costing Japan ¥3.6 trillion ($30 billion) each year to pay for imported fossil fuel being used to substitute for the idled nuclear reactors.(1)

Gaining Approval for Restart

Many of Japan's nuclear reactors were unaffected by the tsunami and earthquake of 11 March 2011 and continued to operate until they reached their next scheduled shut down. All of Japan's 43 operable reactors nuclear reactors are now idled, and the majority have not operated for over three years. Sendai 1 was shut down as scheduled for its periodic inspection in May 2011.

In October 2012 the Nuclear Regulation Authority (NRA), which had taken over from the Nuclear & Industrial Safety Agency (NISA) and NSC, announced that nuclear power plant restart reviews would comprise both a safety assessment by NRA and the briefing of affected local governments by the operators. The assessment would be based on guidelines formulated by NRA in July 2013 after public consultation.

On 28 October 2014, the municipal government of Satsumasendai - which hosts the Sendai plant - and the city's mayor gave its approval for the units' restart.

Apart from local government consent, NRA procedures include review and approval of the detailed design, followed by a plant inspection, as well as a separate assessment and approval of the operating management system. Only when the plant and its operators pass all these requirements can restart occur.

Kyushu Electric Power Company submitted a joint application to the NRA in July 2013 for the necessary permissions to restart both units after completing all NRA requirements.

The NRA approved Kyushu Electric Power Company's proposals for changes to the reactor in September 2014. That approval - which meant the NRA considered the reactor, and the plant as a whole, to be safe for operation - represented by far the major part of the licensing process. Approval of the company's plan for unit 1 was given on 18 March 2015.

Restart Process

Fuel loading for the Sendai 1 reactor was begun on 7 July 2015. Following on from this Kyushu Electric will be carrying out a series of tests to ensure the reactor is ready to restart operations.

The reactor restarted on August 11, and restarted generating electricity on August 14.  The electricity power output of the unit was then gradually increased to full power before a final regulatory inspection.(2) Return to normal operations occurred in early September. 

Japan's Future Electricity Generation Strategy

The Ministry of Economy, Trade and Industry (METI) proposes decreasing Japan's reliance on fossil fuels for electricity generation, to reduce greenhouse gas emissions and reliance on fuel imports.

This is in accordance with its S+3E policy of safety, energy security, economic efficiency and environmental conservation.

Under this strategy the Japanese generation mix will reduce the share of fossil fuels (coal, gas, oil) from 88% at present to 55-58% by 2030. Nuclear generation will supply 20-22%, hydropower around 9% and other renewables (wind, solar, biomass) around 14%.

(1) http://www.jaif.or.jp/en/new-energy-white-paper-describes-effects-of-increased-energy-costs/

(2) http://www.jaif.or.jp/en/restarting-the-sendai-1-nuclear-power-plant/


Related information

Japan: Nuclear Power

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