Japan lifted a tsunami warning Tuesday after a magnitude 7.4 earthquake caused a cooling system to fail for about 90 minutes at the Fukushima-Daini Nuclear Power Plant, bringing back memories of the 2011 disaster in Japan that sent ripples through the global nuclear industry.
Plant owner Tokyo Electric Power Co. (TEPCO) said on Twitter that the cooling-water function for Fukushima-Daini unit 3 spent fuel pool stopped at 6:10 a.m. local time, just after an earthquake off the coast of the Fukushima prefecture, about 150 miles north of Tokyo. The cooling system resumed operation at 7:47 a.m., with the company reporting no abnormalities, injuries, or radiation level changes.
Fukushima-Daini is about 7.5 miles south of the Fukushima-Daiichi Nuclear Power Plant. Both were impacted by a magnitude 9.0 earthquake in 2011 that triggered a 15-meter tsunami wave and killed more than 20,000 people. However, it was Fukushima-Daiichi that suffered catastrophic failure when a prolonged loss of power and cooling capabilities triggered a triple core meltdown and three hydrogen blasts, releasing massive amounts of radioactivity into the air and ocean.
The Japan Meteorological Agency had issued tsunami advisories and warnings for the Fukushima, Miyagi, Iwate, and Ibaraki prefectures, all of which have since been lifted. According to Japan’s public broadcaster NHK, the agency underestimated the size of waves caused by the earthquake Tuesday. The agency warned of one-meter waves and ordered evacuations for both Fukushima and Miyagi. A 1.4-meter tsunami was observed at Sendai Port in Miyagi shortly after 8 a.m., according to NHK.
According to CNN, several tsunami waves were recorded, including one about 22 kilometers off the coast of Iwaki City; another at Port of Soma; and at least one more at Port of Onahama.
NHK said that TEPCO will study whether it responded appropriately to the cooling system failure. The broadcaster reported that TEPCO didn’t inform news media of the failure until two hours after it happened, and that it believes the system’s water pumps stopped working after agitated water in the pool activated an alert system.
