The Japan Nuclear Regulatory Authority (NRA) has approved a report from the Tokyo Electric Power Company (Tepco) on the modernisation and strengthening of safety measures at Kashiwazaki-Kariwa 7 in Niigata Prefecture. This is seen as a step towards restart of the unit, although local consent will still be required.

The Kashiwazaki-Kariwa nuclear power plant was unaffected by the March 2011 earthquake and tsunami but its reactors were previously all offline for two to three years following the 2007 Niigata-Chuetsu earthquake, which caused damage to the site but not to the reactors. While the units were offline, work was carried out to improve the plant's earthquake resistance. However, like all other Japanese NPPs, the plant was closed after the Fukushima accident, pending further safety checks.

In September 2013, Tepco applied for NRA approval of its design and construction plan for Kashiwazaki-Kariwa 6 and 7, submitting information on safety upgrades across the site including at those units. Tepco submitted amendments to its plans in December 2018, July 2019, and in September and October this year.

Kashiwazaki-Kariwa 6 and 7 both 1356MWe Advanced Boiling Water Reactor (ABWR) units that began commercial operation in 1996 and 1997,  were the first Japanese boiling water reactors (BWRs) to be considered for restart.

In October 2017, NRA approved a draft report which concluded that the two units met the new safety standards but noted a number of safety measures that still needed to be taken. These include seismic reinforcements and the construction of a sea wall. It also lists measures to be taken to prevent a serious accident in the event of the loss of on-site power.

Tepco's plan for implementation of these additional safety measures at Kashiwazaki-Kariwa 7 has now been approved. The company plans to complete work to reinforce the safety of the unit in December and will then seek local government approval for restart.

Photo: Kashiwazaki-Kariwa nuclear power plant