Japanese nuclear generation dwindles

28 November 2011

With the shutdown of unit 2 at Kansai Electric Power Company's (Kepco's) Takahama nuclear power plant for a periodic inspection, less than 20% of Japan’s nuclear generating capacity is now in operation.


Kepco announced that Takahama 2 - an 826 MWe pressurized water reactor - was shut down for a regulatory-mandated periodic inspection on 25 November. The company said that the inspection was expected to take four months to complete, but it is not yet known when the reactor will be permitted to restart. In addition to government approval to restart, utilities must also get permission from local authorities. Public opposition to reactor restarts remains high in some areas.


In July, the Japanese government said that reactors would be subjected to stress tests to be conducted in two phases. Step one will be applied to those reactors which have been taken offline for periodic inspections to determine whether they could withstand large earthquakes and tsunamis. Under this step, utilities are required to examine the safety margin of important pieces of equipment in accordance with guidelines set by the country's Nuclear and Industrial Safety Agency (NISA) and Nuclear Safety Commission (NSC). Based on the results of these initial tests, the government is to decide whether a reactor shut for inspections can or cannot resume operation. However, although these tests have been completed at some reactors, no decision has yet been made on restarting any units.


Step two will involve a comprehensive safety assessment of all reactors and will be conducted to enhance the reliability of regular safety checks. These tests will be similar to the stress tests co-ordinated by the European Commission.


As of 28 November, just ten of Japan's 54 power reactors were in operation, according to data released by the Japan Atomic Industry Forum. This represents 9038 MWe, or 18%, of the country's total nuclear generating capacity of 48,960 MWe. Twenty seven units, with a combined generating capacity of 23,930 MWe are not operating as they have been shut for periodic inspection and have not been allowed to restart. A further 17 units, representing 15,990 MWe of capacity have been shut down due to the tsunami or at the government’s request.


According to data released by Japan's Federation of Electric Power Companies (FEPC), electricity generation by the country's ten power companies totalled 71.28 billion kilowatt-hours (kWh) in October - a 5.6% drop from the amount produced in October 2010. Nuclear electricity generation dropped 72.3%, year-on-year, to 6.73 billion kWh. The average capacity factor of Japan's fleet of reactors fell from 70.5% in October 2010 to just 19.5% in October 2011.


Kepco plans to shutdown two further reactors - Ohi unit 2 and Mihama unit 2 - next month for periodic inspections. Unit 3 at its Takahama plant will then be its only operating reactor out of its fleet of 11 units, but that reactor is scheduled to shut for inspections in February 2012.


Meanwhile, Kyushu Electric Power Company is set to take unit 1 of its Genkai plant offline for inspections on 1 December. The utility has also announced that the shutdown of unit 4 of the Genkai plant for a periodic inspection had been postponed slightly from mid-December to 25 December. At that time, all six of Kyushu’s reactors will be idle.


If no reactor restart approvals are given, all of Japan’s units could be out of operation by mid-2012.


Researched and written

by World Nuclear News