With Japan's damaged Fukushima Daiichi nuclear plant spreading trace amounts of radioactivity around the globe, senators on Capitol Hill quizzed nuclear experts Tuesday to find out what lessons from the Japanese nuclear crisis might help safeguard the US reactor fleet.
While nuclear-industry proponents sought to assure the senators that the US reactors are safe, industry critics emphasized that improvements are needed in the areas of spent-fuel storage, emergency backup power, and evacuation procedures.
Officials from the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC) detailed how their agencies had supplied Japan with robots to probe radioactive areas of the Fukushima plant, technical advice from a team of about 40 experts, and 17,000 pounds of equipment.
But what the senators really wanted to know was whether the DOE and NRC had drawn any early conclusions and were taking steps to prevent such a crisis from occurring in the United States. Repeatedly, they were told that those answers would be forthcoming only after the NRC concluded a 90-day review of US reactors – but that US reactors, which had benefitted from continuous upgrades, were safe.
“Are you fully confident that once we've reviewed all of that ... you will be in a position to evaluate whether – if the exact same set of environmental conditions that occurred there were presented here in US – whether or not we would be able to withstand it without a meltdown or release that occurred there?” asked Sen. Mike Lee (R) of Utah.
“In general, yes sir,” responded Peter Lyons, the DOE’s acting assistant secretary for the Office of Nuclear Energy, who proceeded to detail the kinds of assessments nuclear plants undergo to be prepared for a natural disaster.
'Defense in depth'
“We can say with confidence that US nuclear plants continue to operate safely,” Bill Borchardt, executive director for operations at the NRC, told the commission earlier, noting that that confidence was based on a “defense in depth” that included multiple physical barriers to radiation leakage at every reactor and diverse emergency systems.
Senators, however, soon began probing arcane safety issues that had emerged in the press in recent weeks, including the number of hours of battery backup power US nuclear plants are required to have in the event of a station blackout – and the safety of spent-fuel pools at US reactors that have the same design as Japan's stricken reactor.
That General Electric Mark 1 Boiling Water Reactor design – 28 of the nation's 104 reactors are of that type – has spent-fuel pools that sit in the upper part of the reactor building, near the top of the reactors, so cranes can easily load and unload fuel.
Unlike the reactor vessels with their thick steel-and-concrete shells, those pools in the upper reaches of reactor buildings are the weakest part of a plant's “defense in depth” strategy for keeping high radioactivity from reaching the environment, nuclear industry critics say. If breached, the spent-fuel pools at a plant can pose as large, or even larger, threat depending on how much fuel is in them and the age of the fuel.
Improvements for spent-fuel pools
“I understand that the same design is employed at almost a quarter of our plants here in the US,” said Sen. Mark Udall (D) of Colorado. “It seems like this is a design flaw. I'm surprised we haven't addressed it previously. But what are we doing now and what can do to address it in the months and years ahead?”
The NRC’s Dr. Borchardt replied that spent-fuel pools in that particular reactor design had been beefed up in the US to include additional “procedures and pieces of equipment” to keep the spent-fuel pool full of water – including backup power systems.
“Using the best information we had available at the time, both [dry cask and spent-fuel pool] storage systems were deemed to be safe,” added the DOE’s Dr. Lyons, who noted he was at the NRC when those systems were approved. “I look forward to the [90-day] review that will be conducted by the NRC.... I do not have concerns today based on the NRC studies to date.”
Clearly skeptical and dissatisfied with such assurances, Sen. Al Franken (D) of Minnesota questioned Borchardt on how he could be sure that the US knew its nuclear plants were safe if it didn't know the Japanese regulatory system – and where it fouled up.
Uncharacteristically stepping to Borchardt's defense, David Lochbaum, director of the Nuclear Power Project for the Union of Concerned Scientists, said the NRC surely had many experts who knew the Japanese system in detail and could analyze it for mistakes.
Transfer to 'dry cask' storage
But he hammered the NRC's willingness to permit nuclear utilities to hold most of the nation's spent fuel in pools rather than “dry cask” storage.
“All US reactors have more irradiated fuel in spent-fuel pools than in the reactor core,” he said. Yet those critical pools are “cooled by fewer and less reliable systems than are provided for the reactor core.”
Two simple measures, he said, would better manage the risk: accelerate the transfer of spent fuel from pools to dry cask storage. Second, upgrade guidelines for how to address an emergency for spent-fuel pool problems.
A nuclear engineer who worked for many years in nuclear power plants, including those with the same design as the Fukushima plant, Mr. Lochbaum told Sen. Lisa Murkowski (R) of Alaska that there were no technical reasons why such “dry cask” storage could not be done right away.
“Having more irradiated fuel that is less well protected and less well defended is an undue hazard,” he added.
Battery backup power
But perhaps the key takeaway from Japan's nuclear disaster, according to Tuesday’s testimony, was the need to have more battery backup power – especially for nuclear reactors far away from help.
As at Fukushima, US reactors are designed for a station blackout of only a short duration, Lochbaum said. A total of 11 reactors have enough battery backup power to deal with an 8-hour station blackout – just as the reactors in Japan were. But 93 reactors in the US are designed to cope for only four hours.
“I cannot emphasize enough that the lesson from Japan applied to all US reactors, not just boiling water reactors like those affected at Fukushima,” he said. “None are immune to station blackout problems. All must be made less vulnerable.”
Finally, Senator Franken asked about the adequacy of US evacuation plans, given the uneven response in Japan.
“If you take a 50-mile radius around some our reactors you have tens of millions of people,” he said. “Do we have adequate evacuate plans?”
“We think we have the gold standard for emergency planning,” said Anthony Pietrangelo, chief nuclear officer for the Nuclear Energy Institute, a Washington trade organization representing the nuclear power industry.
Franken then posed the question to Lochbaum.
“I think our plans are as good as those of Japan on March 10,” Lochbaum said. “We would be equally in dire straits.... We have great plans on paper. If you put them into practice I think it would show we're going to come up short – just like they were.”