Fire alarm triggered for sixth time in August at Japan's Fukushima Daiichi Nuclear Power Station; fire department confirms no fire occurred

At approximately 3:54 a.m. on August 21, a fire alarm was triggered on the first floor of the access control building at the Fukushima Daiichi Nuclear Power Station. Tokyo Electric Power Company (TEPCO) stated that no open flames or smoke were found near the site; shortly after 5:00 a.m., the fire department confirmed that the alarm was not caused by a fire. Readings from radiation monitoring stations around the plant also showed no significant fluctuations.

This was the sixth fire alarm at the Fukushima Daiichi Nuclear Power Station since the beginning of August. Previously, the maintenance building for Units 5 and 6 triggered a fire alarm on August 8; the emergency diesel generator room for the high-pressure core spray system of Unit 6 triggered a fire alarm on August 12; the main administration building triggered a fire alarm on August 13; the stairwell on the southwest side of the turbine building for Unit 5 triggered a fire alarm on August 15; and the basement of the turbine building for Unit 5 triggered a fire alarm on August 18.

Following each of the above incidents, the fire department confirmed within hours that no fire had occurred, and readings from surrounding radiation monitoring stations showed no notable changes.

TEPCO previously stated that the frequent triggering of fire alarms in recent days may be related to smoke detectors misinterpreting high humidity as smoke. The company said that high-humidity conditions brought by approaching typhoons and rainfall may be one of the factors inducing the alarms. The company plans to send the relevant detectors to the manufacturer for further investigation into the cause of the triggers.