Tepco’s ID-card relapse threatened the restart of its idled nuclear fleet

In early 2021, Tepco reported to Japan’s Nuclear Regulation Authority that intruder-detection equipment at its seven-unit Kashiwazaki-Kariwa plant was malfunctioning — and that an ID card had been used by someone other than its holder. In April 2021 the NRA issued an administrative order prohibiting the company from moving nuclear fuel until improvements were confirmed by inspections. The order stood until December 2023. The plant’s two advanced reactors had been idle since 2011–12, and getting them running was worth an estimated ¥100 billion (about $706 million) in earnings a year.

The way back took four years. In March–April 2024 an IAEA team invited by Tepco found physical protection had been significantly strengthened since 2018 and urged the company to keep the gains from “declining again,” with plant superintendent Takeyuki Inagaki promising stronger prevention against internal threats. Tepco loaded fuel into unit 7 in April 2024 and began loading unit 6 in June 2025. Restart, finally, looked close.

Then the original sin returned. In August 2026 the NRA held an extraordinary meeting over a new case: an operator had used his own ID card to let a colleague out through the central control-room gate of units 6 and 7 — the same class of shortcut that froze the plant in 2021. The regulator assessed the impact on nuclear material protection as “low,” but the pattern was the finding.

On September 14, 2026, the plant’s standing third-party committee — the Improvement Measures Evaluation Committee, chaired by former Osaka High Public Prosecutors Superintendent Toshihiko Itami — met at the site and criticized Tepco in its public session: risk management was insufficient, and the problem could not be dismissed as individual misconduct. The committee exists precisely to judge whether countermeasures have taken hold; its verdict was that they have not.

The 2021 order froze fuel movements until December 2023; units 6 and 7 have been offline since 2011–12 and their restart was worth an estimated ¥100B ($706M) a year

The 2021–23 remediation certified equipment and procedures, but the access-discipline habit on the operations floor — badge sharing between trusted colleagues — survived underneath them.

Exit gates at the central control room ran on personal trust rather than procedure, making violations routine and invisible until one was caught.

The IAEA had named the exact risk in 2024: security gains decline unless internal-threat prevention is continuously reinforced.

The standing committee can document and criticize, but day-to-day incentives on the plant floor are set by management pressure, not committee reports.

Security culture decays the moment enforcement eases. Inspections can certify hardware while the behavior that caused the freeze survives underneath — only consequences hold a habit in place.

The NRA judged the 2026 incident’s impact on nuclear material protection to be low, and no new fuel-movement ban followed the September meeting. But the Improvement Measures Evaluation Committee continues its review, and its September 14 session put Tepco’s claim of a fixed security culture under open doubt: fuel sits loaded in both reactors, local consents are still pending, and every future restart hearing now has to answer for a control-room gate that was opened with the wrong badge.