The chairman of the U.S. Nuclear Regulator Commission said Browns Ferry Nuclear Plant has performance challenges, but he is confident the facility is operating safely.

Intensive NRC inspections following a “red” finding at the plant prompted a visit Friday from Gregory Jaczko and U.S. Sen. Lamar Alexander, R-Tenn.,  who both toured the facility.

The plant is in the second phase of the three-part 95003 inspections, regarded as the most stringent oversight the NRC can offer. The red finding was issued earlier this year in response to a failed valve on the Unit 1 fire mitigation system.

“We evaluate all the plants in this country on a continuous basis, and if we ever see something that would prevent them from providing the ultimate level of safety, we (take action on the issue),” Jaczko said. “Browns Ferry is not in that category right now (though) we do have performance deficiencies.”

The first round of inspections, which concluded Monday, turned up several NRC concerns with testing procedure methods and equipment upkeep. The faulty valve, which failed last October, has since been replaced.

“The particular reason we’re doing the inspection is the valve … did not work appropriately,” Jaczko said. “They’ve showed me they’re replacing the motors powering other pumps and motors for pumps in other systems. … They have accepted our conclusions.”

Alexander, the ranking Republican on the Senate’s Appropriations Subcommittee on Energy and Water Development, said nuclear power plants represent the safest energy systems in America, and he shared Jaczko’s confidence in the stability of Browns Ferry.

“We’ve never had a death as a result of (a nuclear accident). Even at Three Mile Island, no one was even hurt,” he said. “The safety record for both our Navy and civilian reactors leads all forms of energy production.”

He said he appreciated the fact the NRC and the TVA “got on top” of the valve issue at Browns Ferry and created a special team of inspectors to address the problem. He added that the plant’s operating response to the spring tornadoes also assured him the plant was functioning correctly.

“(When) reactors lost their source of power, (the) reactors automatically shut down and generators came back up and worked as they should,” he said.

When asked if the NRC would re-examine the use of the General Electric Mark I boiling water reactors following the nuclear crisis in Fukushima, Japan, Jaczko said inspectors are studying the issue. The same reactors are used at Browns Ferry.

“We have initiated a comprehensive review to learn and apply the lessons learned from the (Fukushima) accidents, and some of those are specific to the boiling water reactors,” he said. “We are working very methodically to identify those issues that put those kind of plans in place for those modifications.”

Alexander added that nuclear reactor safety is “a matter of continuous improvement,” and said the NRC’s four resident inspectors at Browns Ferry continuously look for ways to improve safety.

“While these reactors are complex and there could be an accident, … there have been only four people hurt by radioactivity at Fukushima, but not substantially enough for long-term biological (effects),” he said. “I’m here to make sure the safety inspectors are doing their job, that they’re on the spot and very aggressive.”

In the wake of the April 27 tornadoes, residents and nuclear activists have questioned if Browns Ferry could withstand the force of an EF4 or EF5 tornado. The tornado that ripped through the Tanner community dealt a peripheral blow as it destroyed outlying transmission towers and took down the plant’s seven main transmission lines.

Concerns aired at NRC public meetings include the sheet metal structure housing the plant’s three reactors and exposed pools of water keeping spent fuel rods cool. Both Jaczko and Alexander, however, said they are confident the plant was built to withstand any catastrophic events, including a direct hit from a tornado.

“It is a very robust structure, and in the event of something like that, there are lots of systems that are there to ultimately protect the public,” Jaczko said.

Alexander said the plant’s redundancy safety and power systems offer the public an added layer of protection should a catastrophic storm hit the plant head-on. He said the plant is also examining ways to ensure a steady water flow from the Tennessee River to keep reactors cool in case of a total loss of power.

“(The plant’s) designed to deal with (catastrophic weather events) but they’re also looking at ways to deal with them even better,” he said. “It’s a matter of continuous improvement.”