Some good news for Japanese NPPs

13 September 2016

Kansai Electric Power Company on 8 September released a safety improvement plan to extend the operating periods of units 1 and 2 of Japan's Takahama NPP in Fukui prefecture beyond 40 years. Regulatory approval for operating the units for up to 60 years has already been granted. Under the stricter regulations which came into force in July 2013, Japanese reactors have a nominal operating period of 40 years which can be extended by a maximum of 20 years, provided they meet exacting safety requirements.

Takahama 1 and 2 (780MWe (net) pressurized water reactors) began operating in 1974 and 1975, and in June the Nuclear Regulation Authority (NRA) approved a 20-year operating extension, making them the first Japanese units to be granted a licence extension beyond 40 years under the new regulations. Kansai said work to improve fire protection would begin later in September and would be completed by August 2019. This will involve replacing fire-resistant cabling and the installation of fire protection sheeting, as well as installing additional fire detectors and fire extinguishing facilities. Work to install a new refuelling water tank, and construct a protective wall around it, will also begin in September for completion in August 2019.

Kansai will reinforce the existing concrete wall surrounding the two units’ containment vessels and will install a secondary dome on their containment buildings. This work will begin in February 2017, with completion scheduled for August 2019 at unit 1 and November 2019 at unit 2. The seawater intake facility at unit 2 will also be relocated, and excavation of a new tunnel into the bedrock will begin in May 2017, following by the installation of piping. A protective wall will be built around the new seawater intake facility, with work to be completed in March 2020. The central control panels of both units will also be replaced between April 2018 and August 2019.

Takahama 1 and 2 are the oldest of the seven reactors so far deemed to conform to the new safety standards. They have been offline for routine inspections since January 2011 and November 2011, and are currently undergoing the restart process. In April, NRA confirmed the units meet new safety regulations.  

Unit 3 at Takahama resumed operation on 29 January. Takahama 4 was restarted on 26 February, but was closed again three days later following an automatic shutdown due to a "main transformer/generator internal failure". An injunction imposed by a district court on 9 March has since kept both units offline.

Elsewhere in Japan, the Electric Power Development Co (J-Power) said on 9 September that it would postpone plans to start operating its Oma NPP under construction in Aomori Prefecture by two years until fiscal 2024 because NRA safety tests had taken longer than expected. The Oma NPP will be the world’s first reactor to run solely on plutonium-uranium mixed oxide fuel. This is the second delay since J-Power applied for the safety check in December 2014, with an initial plan aimed at starting operation in fiscal 2021. In September 2015, it rescheduled the restart for fiscal 2022 because of a prolonged NRA screening process after the company was asked to provide further explanations of the plans to build the plant. In the wake of the 2011 Fukushima disaster, the city of Hakodate in neighbouring Hokkaido in April 2014 sued J-Power and government, demanding a halt to construction.

Meanwhile, Kagoshima Governor Satoshi Mitazono indicated on 9 September that he may end his efforts to make Kyushu Electric Power Co immediately suspend the operation units 1 and 2 at the Sendai NPP after the Kyushu Electric President Michiaki Uriu president again rejected the request, arguing that the two units would soon be taken offline for regular maintenance inspections. “Thinking realistically, time is short before regular checkups,” Mitazono told reporters. Unit 1 is due to begin a two-month regular outage on 6 October and unit 2 on 6 December. Oct. 6 and from Dec. 16, respectively, during which the plant’s operation will be suspended.

Kyushu Electric said in writing that its rejection reflected the NRA’s opinion that there was no need to suspend operations of the plant in Satsumasendai. The utility has presented a plan to conduct special checks before the scheduled start of regular checks, to prepare additional vehicles to help evacuate residents living within 30 kilometres of the NPP in case of an accident, and to help remove fallen trees and other objects on evacuation roads when they are blocked after earthquakes and other disasters.

Currently, only three reactors are operating in Japan - the two Sendai reactors and unit 3 at Shikoku Electric Power Co’s Ikata plant in Ehime Prefecture. All reactors were closed in the wake of Fukushima. 



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