Safety upgrade plan approved for Kashiwazaki-Kariwa unit

Tepco applied for NRA approval of its design and construction plan for Kashiwazaki-Kariwa units 6 and 7 in September 2013. It submitted information on safety upgrades across the site and at those two units.

Kashiwazaki-Kariwa 6 and 7 - 1356 MWe Advanced Boiling Water Reactor units that began commercial operation in 1996 and 1997, respectively - were the first Japanese boiling water reactors (BWRs) to be put forward for restart. The company subsequently submitted amendments to that plan in December 2018, July 2019, and in September and October this year.

In October 2017, the NRA approved a draft report that concluded units 6 and 7 met the country's new safety standards. The document mandated a number of safety measures to be taken at the site. These include seismic reinforcements and construction of a seawall. It also lists measures to be taken to prevent a serious accident in the event of the loss of on-site power. Under the new safety requirements, BWRs must be equipped with filtered venting systems.

The NRA has now approved Tepco's plan for the construction and implementation of these additional safety measures at unit 7 of the Kashiwazaki-Kariwa plant.

Tepco said: "Since applying for design and construction plan approval on 27 September, 2013, we have received various suggestions at review meetings, etc, in order to further improve the safety of the Kashiwazaki-Kariwa nuclear power station. We are proceeding with our efforts. We will continue to obtain approval for safety regulations, the remaining work for the completion of safety measures work, inspections before use, etc, but we will continue to make steady efforts to improve safety."

It plans to complete work to reinforce the safety of unit 7 in December.

Kashiwazaki-Kariwa was unaffected by the March 2011 earthquake and tsunami, which damaged Tepco's Fukushima Daiichi plant, although the plant's reactors were previously all offline for two to three years following the 2007 Niigata-Chuetsu earthquake, which caused damage to the site but did not damage the reactors themselves. While the units were offline, work was carried out to improve the plant's earthquake resistance.

Although it has completed work at the other idled units at Kashiwazaki-Kariwa, Tepco is concentrating its resources on units 6 and 7 while it deals with the clean-up at Fukushima Daiichi. Restarting those two units - which have been offline for periodic inspections since March 2012 and August 2011, respectively - would increase the company's earnings by an estimated JPY100 billion (USD950 million) per year.

Tepco also owns the Fukushima Daini plant. In July 2019, Tepco announced its official decision to decommission the four reactors there, which are close to the damaged Fukushima Daiichi plant.