Japan's Nuclear Regulation Authority (NRA) on 24 March decided to effectively prevent Tokyo Electric Power Company Holdings (Tepco) from restarting its Kashiwazaki-Kariwa NPP in Niigata Prefecture following the discovery of serious safety flaws. NRA decided at its meeting to ban Tepco from transporting nuclear fuel to the plant or loading it into the reactors. A final decision will be made after Tepco is given an opportunity to provide an explanation. The restrictions will remain in effect until Tepco's response to the incident is "in a situation where self-sustained improvement is expected," according to NRA.
Earlier in March, the Kashiwazaki-Kariwa plant was found to have been vulnerable to unauthorised entry at 15 locations since March 2020 because of defective intruder detection systems and backups. NRA provisionally rated the security breaches to be at the worst level in terms of safety and severity - the first time it has given such an assessment.
"We have yet to thoroughly confirm whether measures to protect nuclear material at Kashiwazaki-Kariwa are sufficient. If we ban the transport of nuclear fuel, the protection of such material will be enhanced," NRA Chairman Toyoshi Fuketa said at the meeting. Other commissioners at the meeting agreed with the ban. The commissioners also considered other disciplinary actions including revoking Tepco's licence to operate the complex or ordering the halt of plant operations for up to a year.
This is the second time NRA has issued a corrective order based on violation of the law regulating nuclear source material, nuclear fuel material and reactors. In 2013, it effectively banned the restart of the Monju prototype fast-breeder reactor after its operator was found to have failed to inspect nearly 10,000 devices at the reactor in Fukui Prefecture.
Tepco had wanted to resume operation of the Kashiwazaki-Kariwa plant to reduce its dependence on costly fossil fuel imports for non-nuclear thermal power generation. It is also facing huge compensation payments and other costs stemming from the 2011 Fukushima Daiichi accident. The seven-unit Kashiwazaki-Kariwa complex was one of the world's largest NPPs with a combined output capacity of 8, 210MWe when it was fully operational. Units 6&7 cleared safety screenings by the NRA in 2017, paving the way for the resumption of operations. However, in addition to the latest security issues, safety upgrades have not yet been completed at unit 7, and fuel loading, originally scheduled for March and April, had already been revised to "undecided”.
