The powerful earthquake that rocked the Tohoku region Tuesday morning temporarily stopped the critical cooling system for a spent fuel pool at the Fukushima No. 2 nuclear plant for about 100 minutes, Tokyo Electric Power Company Holdings Inc. said.
The cooling system was automatically shut down at 6:10 a.m. at the pool for the No. 3 reactor after sensors detected changes in the water level of a tank that pumps cooling water into the pool, which is home to 2,360 still-hot spent fuel assemblies and 184 unused ones.
Tepco spokesman Kenichi Nakakuki said the quake likely shook up the water inside the tank, triggering the automatic shutoff.