Nuclear plant emergency generators like those that failed in Japan following the March earthquake and tsunami also failed during tests at the Seabrook Station in New Hampshire and 32 other US plants in the past eight years, according to a report by US Representative Edward J. Markey’s office.
The report was issued yesterday by the Malden Democrat’s office as a federal task force vouched for the safety of the nation’s nuclear plants in the aftermath of the Japanese crisis, triggered in part by the failure of backup generators at one plant.
The Seabrook incident, according to the report, took place in August 2006, when the plant shut down because of “inoperable emergency diesel generators.’’ The generators were inoperable for one day.
Alan Griffith, a spokesman for NextEra, which owns Seabrook, said the problem occurred when one of two backup generators was taken down for routine maintenance and a voltage problem occurred at the other during a test. It was quickly repaired, but Nuclear Regulatory Commission rules require the plant to shut down if a certain number of generators are not operational.
Markey criticized the NRC for becoming too cozy with the industry it oversees and compromising safety. The report noted that NRC regulations do not require emergency diesel generators to be operational when there is no fuel in a nuclear reactor core — creating the possibility that in a power failure, spent fuel rods stored on site could be left without a functioning cooling system. In Japan, large amounts of radioactive material escaped from a spent-fuel pool at the Fukushima Daiichi plant after cooling systems failed. Japanese officials said yesterday that one of the reactors at that plant appears to be more damaged than originally thought.
“An examination of NRC regulations demonstrates that flawed assumptions and under-estimation of safety risks are currently an inherent part of the NRC regulatory program, due to a long history of decisions made by prior Commissions or by the NRC staff that have all too often acquiesced to industry requests for a weakening of safety standards,’’ the report said.
Markey, a nuclear opponent, hopes the report persuades the NRC not to issue license extensions for nuclear plants until it finishes reviews and upgrades its safety requirements. That appears unlikely to happen — since the Japan quake, the agency has approved a 20-year license renewal at Vermont Yankee and at three reactors at an Arizona plant.
But even as the task force gave safety assurances yesterday, its members said they are likely to recommend changes in rules to enhance safety and preparedness of US plants — and lower the level of risk. The group, made up of senior NRC staffers, said it will address a range of issues at nuclear plants, including their ability to cope with prolonged power outages caused by earthquakes, fires, or other catastrophes.
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Markey’s report homed in on backup generators whose failures rendered them inoperable for at least a day, noting there have been at least 69 reports of problems with emergency diesel generators during testing at 33 nuclear plants. A total of 48 reactors were affected. The failures included 19 that lasted over two weeks and six that lasted longer than a month, the report says.
Neil Sheehan, a NRC spokesman, said that the agency takes “the maintenance and testing of emergency diesel generators very seriously, as their lack of availability raises plant safety risk. The NRC has taken enforcement action against many plants for problems involving the generators. We also track issues associated with them through our Performance Indicators and inspections.’’
At Seabrook, Griffith stressed that there are three separate power lines that come into the plant and multiple levels of redundancy in case of power loss.
“These generators are not used to run the plant [day to day], they are for emergencies,’’ he said. “What is most important is that there are multilayered safety systems in place to ensure there is always sufficient power.’’
At the Globe’s request, the NRC searched its records for reports of other problems involving backup generators at New England plants. The agency said it found problems at both Seabrook and the Pilgrim Nuclear Station in Plymouth and there could be more. Most involved tests or inspections of the systems.
In 2001, a violation of “low to moderate safety significance’’ was given to Seabrook for not fixing degraded components related to emergency generation. And the plant got the same level of violation in November 2009 when it failed to assure suitable parts were chosen for a generator, which failed as a result.
Pilgrim, owned by Entergy, also received two citations, although for more minor issues. In 2005, it failed to develop adequate instructions to start a diesel generator if power was lost — during an actual loss of power to auxiliary equipment, a generator did not start. And in May 2009, it was cited by the agency for failing to ensure there was an adequate supply of air to generators, which resulted in one generator becoming inoperable during a test. Entergy fixed that problem right away, and a spokeswoman said yesterday that both issues were minor.
“In both instances, two other emergency diesel generators were available as backup power if needed during the short time frame the others were not operable, as well as other electric power sources,’’ spokeswoman Carol Wightman said.
Material from the Associated Press was used in this report.