U.S. nuclear plants hit by storm are stable: NRC

WASHINGTON (Reuters) - The U.S. nuclear safety regulator took a closer look at the ability for U.S. plants to withstand power blackouts on Thursday, a day after severe storms and tornadoes knocked out power to three nuclear reactors in Alabama.

The plants were stable and the safety systems performed as designed, said Gregory Jaczko, chairman of the Nuclear Regulatory Commission.

"All of the available diesel generators started and loaded, and ultimately, the core cooling systems are operating normally. In addition, the spent fuel cooling is currently in service. All these plants are stable," Jaczko said.

Jaczko spoke ahead of a briefing on the failed Fukushima Daiichi nuclear power plant in Japan, which was crippled when an earthquake and tsunami knocked out its power.

Commissioners are examining the rules and regulations designed to ensure U.S. plants can withstand blackouts as part of the U.S. response to the Japan disaster.

A top NRC official said Japanese officials are making progress on addressing safety and environmental issues at the plant.

The situation at Fukushima is not yet stable, said Bill Borchardt, NRC's executive director of operations. There were still many unanswered questions about the status of equipment at the plant, he said.

(Editing by Alden Bentley and Lisa Shumaker)