Upgrades to safety measures to comply with new regulatory requirements were completed yesterday at unit 7 of the Kashiwazaki-Kariwa nuclear power plant in Niigata prefecture, Tokyo Electric Power Company (Tepco) has announced. Although the utility has already received regulatory approval to restart the reactor, it must still obtain local consent.

Tepco applied for Nuclear Regulatory Authority (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 2020.

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 approved Tepco's safety measures for Kashiwazaki-Kariwa unit 7 on 14 October last year.

Tepco announced today that work to reinforce the safety of that unit has now been completed. These include the construction of a 15-metre high seawall to protect the unit from tsunamis, as well as the installation of flood barrier walls and panels to protect the reactor building.

"Going forward, Tepco will continue to conduct strict inspections to confirm safety and engage in voluntary safety measure renovations aimed at further improving safety," the company said. "Furthermore, we will take advantage of various opportunities to explain the details of the safety measure renovations that were implemented at the Kashiwazaki-Kariwa nuclear power station, as well as the status of inspections and future schedules, etc, to not only parties concerned, but also the residents of Niigata Prefecture. We shall also leverage these opportunities to listen to the opinions of prefectural residents and reflect those opinions in Tepco initiatives."

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.

Researched and written by World Nuclear News