Plant safety is a hot topic at the Davis-Besse Nuclear Station as two direct-current electrical systems were in “an unanalyzed condition that significantly degrades plant safety” for years, according to the Nuclear Regulatory Commission (NRC).
While the NRC said the two issues existed long before Japan’s Fukushima crisis, it did not see either as an imminent threat. It allowed the plant’s owner, FirstEnergy Corp., to continue operating the Oak Harbor, OH, nuclear plant at full power.
In its report, FirstEnergy said backup lift oil pump motors were not “environmentally qualified” with an emergency lighting panel inside the nuclear containment area.
“This could challenge the adequacy of electrical separation between the potentially grounded nonsafety related equipment and the safety related batteries [in the event of an accident],” the utility said.
FirstEnergy’s report to the NRC also said a ground fault in automatic transfer switches “could be transferred from one power source to the redundant source, potentially impacting the ability of both safety-related DC power sources to perform their required functions.” The plant’s license forbids that scenario, the report said.
The company just corrected the issues, said Jennifer Young, FirstEnergy spokesperson. She also said the utility has extensive backup systems in place.
David Lochbaum, nuclear safety engineer for the Cambridge, Mass.-based Union of Concerned Scientists and a former NRC trainer, said Davis-Besse’s wiring is just one of the electrical issues gaining prominence at the U.S.’ 104 nuclear plants in the aftermath of the Fukushima disaster, which began with a March 11 earthquake and tsunami. The systems then faced a large amount of electrical problems that rendered safety systems inoperable at multiple plants in Japan.
“Somehow, accidents make people smarter,” Lochbaum said, explaining Davis-Besse’s wiring irregularities likely have existed for decades.
FirstEnergy and the NRC said they are part of the plant’s design basis. Davis-Besse went online in 1977.
It is amazing, Lochbaum said, the first post-Fukushima look at Davis-Besse’s wiring configuration “magically vaporized all the clouds or curtains or whatever had been hiding this safety violation for all those decades.”
If the nonqualified electrical component had shorted out, an electrical fault could have disabled all of the safety equipment sharing that panel, he said.
“So workers opened a breaker, effectively removing the offending equipment from the supposedly protected panel,” Lochbaum said. “Now, workers and NRC inspectors look at AC and DC power problems in a new light. That new perspective is flushing out old problems.”
Scott Burnell, spokesman for the NRC’s headquarters in Rockville, Md., said Lochbaum is making too much of the post-Fukushima inspections.
The NRC has had a special task force examining lessons learned from the Japan disaster. It issued a 12-point set of recommendations on July 13, agreeing that America’s nuclear plants need to become safer, he said.