The Nuclear Regulatory Commission will hold another inspection of the San Onofre power stations and a public meeting before announcing whether Southern California Edison will be allowed to resume moving spent nuclear fuel at the defunct plant.
The NRC held a three-hour webinar Thursday to hear Edison’s proposed corrective actions, after a near-miss accident halted radioactive waste transfers last year.
A stainless steel canister loaded with more than 50 tons of spent nuclear fuel was suspended without supports for almost an hour when operators failed to notice it had not downloaded properly into a concrete storage bunker.
Edison officials told the NRC that the utility has conducted extensive evaluations and put effective corrective actions in place. The company has hired more oversight staff, beefed up training and installed extra cameras to monitor loading operations.
"Management failed to recognize the complexity and risks associated with a long-duration fuel transfer campaign, while using a relatively new system design," Edison stated as a root cause.
Chief Nuclear Officer Doug Bauder told the NRC panel that an analysis showed the canisters were designed to withstand a drop of up to 25 feet. He said the analysis had been reviewed by Edison, the maker of the canisters Holtec International and an independent third party.
Linda Howell, deputy director of the NRC’s Division of Nuclear Materials Safety, asked what the utility company’s contingency plan is, should a canister be damaged in an accidental fall. After a long pause, Bauder said the operation would stop, and because potential damage would be to fuel held within the container, there would be no threat to employees or the public. He said the company would have plenty of time to develop a strategy to deal with the situation.
Howell said that when inspectors come to the plant to see if corrective actions are adequate, they will ask the company about contingency plans in case of a canister fall.
NRC staff questioned Edison officials about the risk that scratches to the canisters while downloading could lead to cracks. Edison engineer Jerry Stephenson said the scratches were evaluated in great detail and determined to be no more than two sheets of paper thick. When asked how the utility can be sure the analysis will be adequate to ensure the canisters' integrity in the long term, Bauder said the utility’s aging management process would look into that.
Critics of Edison's handling of the fuel transfer said the storage design is faulty and that correcting procedures, oversight and training will not solve safety problems.
“It is important to note these Holtec engineering design problems cannot be fixed with training and procedures,” retired Adm. Len Hering said. “The Holtec HI-STORM UMAX system is seriously flawed and the NRC should be held responsible for not citing Holtec accordingly.”
Scott Morris of the NRC’s Region 1V, said the agency will rule within 45 days on the seriousness of the violations that led up to the near-miss accident. He said the NRC will send inspectors to San Onofre to do a follow-up examination to see if Southern California Edison is ready to resume transferring the spent fuel.
Morris concluded that operations would not resume before another public meeting to announce the results of the follow-up inspection.
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