ROCKVILLE, Maryland (AP) -- Inspectors have found problems with equipment, training and procedures at some U.S. nuclear reactors, but none serious enough to undermine confidence in the plants' continued safe operation, federal regulators said Thursday.
The problems identified during inspections over the past two months did not pose a significant safety risk and have been corrected, the Nuclear Regulatory Commission said.
The comments came as a task force of senior NRC staffers briefed the five-member panel on a safety review of U.S. nuclear reactors being conducted in response to the nuclear crisis in Japan.
"As we stand today, the task force has not identified any issue we think would undermine our confidence in the continued safety and emergency planning of nuclear plants in this country," said Charles Miller, who oversees environmental management programs for the NRC and is leading the review.
Marty Virgilio, the NRC's deputy executive director, cited problems with equipment and procedures intended to cope with extreme events such as natural disasters or terrorist attacks, rather than issues involving design flaws. He did not say where the problems were found.
An agency spokesman said that problems were identified at less than one-third of the 104 U.S. nuclear reactors.
The problems included emergency pumps that were missing or did not work, or equipment that was stored in areas that could be vulnerable to earthquakes or floods, said Eliot Brenner, an NRC spokesman.
"None of the observations posed a significant safety issue," Virgilio told the commission Thursday. "At this point in time it's our understanding that whatever has been found has been corrected."
The disclosure of the inspection findings followed a bulletin issued Wednesday by the nuclear agency ordering U.S. plants to show they had the proper equipment and staff to respond to a terrorist attack or other extreme event, such as a fire or flood.
The demand for information from plant operators is one of several actions the NRC is taking in response to the Japan crisis and is separate from a 90-day safety review being conducted by the NRC task force. The agency also has ordered resident inspectors to step up spot checks of the 65 U.S. nuclear power plants -- an action that identified the problems disclosed on Thursday.
Meanwhile, federal regulators ordered an in-depth inspection this week at an Alabama nuclear plant after deciding the failure of an emergency cooling system there could have been a serious safety problem.
The NRC issued a rare "red finding," its most severe citation, against the Tennessee Valley Authority, which runs the Browns Ferry nuclear power plant near Athens, Alabama. Regulators said a stuck valve could have caused an emergency cooling system to fail.
In a progress report Thursday, the NRC task force said it probably would recommend changing federal rules to upgrade safety and preparedness.
The group of senior NRC employees said it will address a range of issues, including the ability of plants to deal with prolonged power outages caused by earthquakes, floods, fires or other catastrophic events.
NRC chairman Gregory Jaczko has questioned whether U.S. reactors are prepared for the type of days-long power outage that struck a nuclear power plant in Japan following the March 11 earthquake and tsunami.
The agency has mandated that U.S. plants need only cope without power for four hours to eight hours. After that time, the policy assumes some electrical power would be restored, either from the power grid or emergency diesel generators that are required at all plants.
The task force did not make a recommendation on "station blackouts," but Miller said it probably would address the issue in a 90-day report due in July.
The group also will look at ways to prevent long-term damage to the core reactors and spent fuel pools in the event of a long-term blackout, said Miller, who briefed the five-member commission.
The NRC set up the panel in late March, saying it was important to apply lessons learned from Japan. The task force is conducting two reviews, a 90-day report due in July and a long-term analysis due in January.
Rep. Edward Markey, a longtime opponent of nuclear power, released a separate report highlighting what he called inadequacies at the NRC that could affect oversight of U.S. plants.
Markey said emergency diesel generators have failed repeatedly at dozens of plants in recent years. At least 69 incidents of diesel generator failures have been reported at 33 nuclear plants in the past eight years, he said.
NRC regulations do not require emergency diesel generators to operate when there is no fuel in a nuclear reactor core, even though that could leave spent fuel pools without any back-up cooling system in case power is lost, the report said. In Japan, large amounts of radioactive material escaped from a spent fuel pool at the stricken Fukushima Dai-ichi nuclear plant after cooling systems failed.
Markey's report said the NRC should do more to prevent hydrogen explosions at nuclear reactors and spent fuel pools, and should update seismic safety requirements for nuclear reactors. The Fukushima plant experienced several hydrogen explosions after the earthquake and tsunami.