The plan, which has been revised for the first time since 2017, included an outlook for future revenue and expenditures, assuming that the Kashiwazaki Kariwa-7 reactor would be restarted in October 2022 at the earliest and Kashiwazaki Kariwa-6 in April 2024. It also said that one out of the remaining reactors, Units 1 to 5, would be restarted in 2028.
The revised cost benefit of restarting a reactor was estimated to be about 50 billion yen ($450m) per unit to reflect changes in fuel prices and other factors. This was down from 90 billion yen in the previous plan.
In April, Tepco said it would accept sanctions imposed by regulators over a lack of anti-terrorism measures at Kashiwazaki Kariwa-7, a step that would prevent the restart of the facility for at least a year.
Tepco made the announcement in response to a decision by the Nuclear Regulation Authority (NRA) in late March to ban it from moving any nuclear materials at Kashiwazaki Kariwa-7. The measure means steps to restart the plant have been on hold.
Regulators found malfunctioning anti-terrorism equipment and inadequate protection of nuclear materials at multiple locations at the plant from at least 2018.
NRA chairman Toyoshi Fuketa said Tepco has since restored the safety functions, but the problems were deemed serious and systematic.
In January 2021, Tepco said upgrades to safety measures to comply with new regulatory requirements introduced after the March 2011 Fukushima-Daiichi accident had been completed at Kashiwazaki Kariwa-7. Fukushima-Daiichi is also owned and operated by Tepco.
The company said work included the construction of a 15-metre-high seawall to protect the unit from tsunamis and the installation of flood barrier walls and panels to protect the reactor building.
The seven-unit Kashiwazaki Kariwa facility was not affected by the earthquake and tsunami which damaged Fukushima-Daiichi nuclear station in March 2011. The station’s reactors were all offline at the time following a 2007 earthquake which damaged the site but did not damage the reactors themselves.
While the units were offline, work was carried out to improve the facility’s earthquake resistance. However, like all other Japanese nuclear plants, Kashiwazaki Kariwa was closed after the Fukushima-Daiichi accident, pending further safety checks.
Tepco said in June 2020 it was concentrating its resources on restarting the newer Units 6 and 7 at Kashiwazaki Kariwa while it also dealt with the cleanup at Fukushima-Daiichi. Units 6 and 7 originally began commercial operation in 1996 and 1997 respectively.
In October 2017, the NRA approved a draft report that found that Units 6 and 7 complied with the country’s new safety standards, with a number of additional recommendations, including the seawall and flood barrier.
Tepco president Tomoaki Kobayakawa said at a press conference that the understanding of local residents would be a prerequisite for restarting nuclear power plants.
The Nuclear Damage Compensation and Decommissioning Facilitation Corporation, which oversees Tepco, will continue to monitor the company’s efforts to reform its management, aiming to re-examine the nature of the government's involvement after three years.