WASHINGTON -- Nuclear Regulatory Commission staffers are rejecting the concerns of lawmakers, state officials and watchdog groups who say nuclear waste tightly packed in spent-fuel pools at U.S. power plants is vulnerable to terrorist attacks.
In recent months, lawmakers and activists have been pushing NRC officials to address concerns that the spent-fuel pools -- many of which are currently filled beyond their originally intended capacity -- are at risk of causing a catastrophic fire. If an act of terrorism or nature caused water in the pools to drain, a fire could ensue and radiation could be dispersed throughout the surrounding area, they say.
The critics have urged the commission to require plant operators to move spent fuel rods into dry cask storage as soon as the rods complete a necessary five-year cooling-off period in the pools.
In a memo made public on Monday, NRC staff concludes, however, “that the expedited transfer of spent fuel to dry cask storage would provide only a minor or limited safety benefit … and that its expected implementation costs would not be warranted.”
The Nov. 12 document recommends “that additional studies and further regulatory analyses of this issue not be pursued,” and that the issue -- one of several that the commission is reviewing in light of the Fukushima disaster in Japan -- “be closed.”
The five-member, presidentially appointed commission has yet to act on the staff memo, which members of the Senate Environment and Public Works Committee are expected to scrutinize during a Capitol Hill hearing on Thursday. The five commissioners will testify at the hearing, to be chaired by Senator Barbara Boxer (D-Calif.).
The memo released this week relies in part on a study that NRC staff conducted this year regarding the impacts a major earthquake could have on aging U.S. reactors built using the same General Electric design as the Fukushima plant. Lawmakers, state officials and watchdog groups have argued that the study of the so-called “Mark I” design is flawed.
Senator Edward Markey (D-Mass.) in a Sept. 17 letter called the study “biased, inaccurate and at odds with the conclusions of other scientific experts -- including those expressed in a peer-reviewed article that was co-authored” by current NRC Chairwoman Allison Macfarlane in 2003 and a separate study completed by the National Academy of Sciences in 2004.
Markey said that at Mark I and similar Mark II reactors, “spent fuel pools are located at the top reactor building and thus are particularly vulnerable to terrorist attacks or natural hazards.” He raised concerns that the Pilgrim Nuclear Generating Station in Massachusetts “was originally licensed to hold about 880 spent fuel assemblies in its spent fuel pool, but currently holds about 4,000.”
According to Markey, “the more densely these fuel assemblies are packed into a spent fuel pool” the more likely it is they “could spontaneously ignite and … release massive quantities of radiation into the environment.”
The Massachusetts senator charges that rather than study the issue “anew,” NRC staff was charged with confirming the agency’s past conclusion that spent fuel pools are safe. “In other words, the NRC had already reached its conclusion before the study was ever begun,” Markey said.
In the senator’s view, the study considered only the likelihood of a severe earthquake and not a terrorist attack. It also weighed only the possibility of total water loss in spent fuel pools and not partial loss, his letter said. The assessment additionally “failed to model the possibility that a hydrogen explosion like those that occurred at Fukushima could generate debris in the spent fuel pool that impeded cooling,” Markey wrote.
Moreover, the new study did not properly address the benefits of switching from currently used “high-density” spent fuel configurations to the “low-density” approach that critics are advocating, Markey argued. NRC staff simply compared a scenario in which a high-density spent fuel rack was less full than one that was filled to capacity, he said, arguing that the study instead should have compared the current scenario to one in which low-density racks are used, Markey said.
Critics argue that low-density racks -- which were used in U.S. reactors prior to NRC approving the high-density versions -- improve the flow of water between spent fuel rods and improve the overall safety of the pools. In an August critique of the NRC study, Gordon Thompson, an engineer and senior research scientist at Clark University, backed this view.
“NRC misuses the phrase ‘low density' in order to create a false impression of the study’s scope,” Thompson said. “This pretense reflects pre-determined conclusions based on a ‘feeling.’”
Thompson’s critique was submitted to NRC staff by Diane Curran, a lawyer who represented several watchdog groups in successful litigation against the commission regarding its so-called “waste confidence” rule.
The suit, filed with several state governments, prompted a federal court finding that the commission had determined it was confident reactor waste would eventually be safely disposed in an underground repository without considering the prospect of spent fuel pool fires in the interim. It also failed to adequately consider the Obama administration’s cancelation of the Yucca Mountain repository project in Nevada, the court said.
Mary Lampert of the Massachusetts-based watchdog group Pilgrim Watch told Global Security Newswire that critics would continue to press the commission on the spent fuel pool issue as it revises the waste-confidence rule in response to the court ruling. The commission is accepting public comment on the new draft rule through Dec. 20 and will keep all reactor licensing decisions on hold until the new rule is finalized.
NRC staff, in an October response to critics, defended the study, including the complaint that the review was limited to the prospect of severe earthquakes. The study “focused on an earthquake because it is the event shown by past studies to dominate spent fuel pool risk,” the NRC response states. Following the September 2001 terrorist attacks on New York and Washington, NRC staff completed separate, classified studies on the prospect of terrorism attacks, according to the agency.
In addition, in the Nov. 12 memo, NRC staff contended that it had addressed the critics concerns by using “conservative assumptions” in its analysis.
The nuclear power industry, meanwhile, has praised the NRC study and defended the safety of spent fuel pools.
“The storage pools at Fukushima survived the fourth-largest earthquake in recorded history, hydrogen explosions that blew the roofs of three of the reactor buildings and the debris resulting from those explosions,” Steven Kraft, senior technical adviser for the Nuclear Energy Institute said in an Oct. 9 statement. “All accounts from Japan tell us that the fuel in those pools survived with minimal if any damage.”