Nuclear regulators raise severity level

Associated Press

TOKYO

Workers at Japan’s tsunami-stricken nuclear power complex discovered a small fire near a reactor building Tuesday, but it was extinguished quickly, the plant’s operator said.

The setback was a further sign that the crisis at the plant has not abated, and came amid reports that Japanese nuclear regulators were raising the severity of the accident to the highest level, 7, on par with the Chernobyl disaster in 1986.

Tokyo Electric Power Co., which operates the disabled Fukushima Dai-ichi nuclear power plant, said the fire at a box that contains batteries in a building near the No. 4 reactor was discovered about 6:38 a.m. Tuesday and was put out seven minutes later.

It wasn’t clear whether the fire was related to a magnitude-6.3 earthquake that shook the Tokyo area this morning. The cause of the fire is being investigated.

“The fire was extinguished immediately. It has no impact on Unit 4’s cooling operations for the spent fuel rods,” said TEPCO spokesman Naoki Tsunoda.

The plant was damaged in a massive tsunami March 11 that knocked out cooling systems and backup diesel generators, leading to explosions at three reactors and a fire at a fourth that was undergoing regular maintenance and was empty of fuel.

The magnitude-9.0 earthquake that caused the tsunami immediately stopped the three reactors, but overheated cores and a lack of cooling functions led to further damage.

Engineers have been able to pump water into the damaged reactors to cool them down, but leaks have resulted in the pooling of tons of contaminated, radioactive water that has prevented workers from conducting further repairs.

Aftershocks on Monday briefly cut power to backup pumps, halting the injection of cooling water for about 50 minutes before power was restored.