Tepco to Restart Kashiwazaki-Kariwa Unit 6 Feb 9 After Alarm

Tokyo Electric Power Company confirmed plans to restart Unit 6 of the Kashiwazaki-Kariwa nuclear power plant on Feb 9 after aborting a January startup when an alarm tripped during control-rod withdrawal operations. Tepco’s investigation found the alarm was triggered by an inverter fault-detection function added in 2023, which flagged a delay in current rise on one motor lead that was within normal operating range. Because the function is not required for safety, Tepco disabled that detection setting and adjusted its restart procedures.

Tepco will carry out stepwise checks of each control-rod drive motor as the unit is brought back online. The company intends to raise reactor pressure gradually, resume generation and transmission on Feb 16, and conduct a temporary shutdown for inspections around Feb 20. Final confirmation with Japan’s Nuclear Regulation Authority will follow, with commercial operation targeted on March 18, 2026.

The technical sequence matters because control-rod drive motors are fundamental to reactor shutdown and reactivity control. The alarm related to current rise on a motor lead rather than an outright equipment fault, and Tepco judged the inverter’s detection setting to be a nuisance trip rather than a safety issue. Operators will therefore validate each drive motor in sequence, a conservative approach that puts equipment checks and regulatory confirmation before full commercial load.

Kashiwazaki-Kariwa is a seven-unit site with several reactors taken offline after the 2011 Fukushima events. Unit 6 is one of the reactors that has been through extensive restart preparation, including fuel management and local government approvals. Returning Unit 6 to service will supply additional baseload power to the regional grid and is expected to have measurable economic impact on Niigata prefecture through increased output and associated employment and tax receipts.

For community members and local energy stakeholders, the schedule sets concrete milestones to watch: physical restart operations on Feb 9, generation restart on Feb 16, an inspection pause around Feb 20, and the target for commercial operation on March 18. Verify Tepco updates and Nuclear Regulation Authority confirmations for any schedule changes or additional inspections. The technical fix and stepwise motor checks reduce the immediate risk of another unplanned halt, but the sequence of inspections and regulatory sign-off means the return to full commercial service will still depend on successful verification at each stage.