Monthly Report

Tohoku EPCO halts Onagawa Unit 2 just days after restart due to calibration equipment problem

November 5, 2024
Onagawa Nuclear Power Plant
Onagawa Nuclear Power Plant’s Unit 2 was restarted on October 29, 2024. (Image: Tohoku EPCO)

On November 4, 2024, Tohoku Electric Power halted Onagawa Nuclear Power Plant’s Unit 2 due to an issue with a measuring device discovered the day before. The effect this will have on the timeline of the reactor’s return to commercial operation, which was planned for December 25, 2024, is unclear at this point.

The issue occurred when a device for calibrating a neutron measuring device inside the reactor stopped working while it was being placed into the reactor. After noticing the anomaly, Tohoku EPCO removed the device, placed it in a shielded container, and halted the reactor. It is currently investigating the cause of the issue.

According to the company’s statement, “This incident has not had any radioactive impact on the environment around the power plant”

The 825MW reactor was brought online on October 29, 2024, becoming the first active nuclear power plant in the Tohoku region, which suffered the heaviest damage during the 2011 Great East Japan Earthquake. It is not clear how much the unit’s return to commercial operation will be delayed due to the current halting.

“In order to restart operations (restart power generation), we will investigate the cause of this incident and will continue to prioritize safety while thoroughly addressing each and every process,” said Tohoku EPCO’s statement.

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