Southern California Edison has fixed safety concerns around how it transfers spent nuclear fuel from wet cooling ponds to dry cask storage, officials from the Nuclear Regulatory Commission said Monday.
Regulators had already given the utility the go-ahead to resume transfers two weeks ago and said they would explain why during a June 3 webinar open to the public.
The decision comes less than a year after fuel transfers stopped at San Onofre when a canister of radioactive spent fuel was suspended without support 18 feet above the ground for nearly an hour. It had caught on a ring within the storage vault.
In a public webinar, Linda Howell, deputy director in the Division of Nuclear Materials Safety at the NRC, said Edison’s corrective actions following the near accident were satisfactory.
"NRC noted that while certain weaknesses in the licensee's corrective actions were observed, with one exception, all corrective actions and observed weaknesses had been addressed as of [March 25th]," said Howell.
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That one concern was potential for scratching on the canisters while they were being lowered into their vaults. She said Edison had done extensive analysis on these scratches and whether they complied with standards from the American Society of Mechanical Engineers, and they checked out.
She says after an independent assessment, they believed the utility's conclusions on the structure of their canisters were "conservative" and reasonably reflective of "the anticipated scratch or wear from operational activities."
But, she said regulators will still be keeping an eye on what the utility does next.
"Once the licensee resumes fuel transfer operations, we will initiate unannounced inspections that will be performed frequently to observe the licensee’s implementation of their enhanced programs," said Howell.
In a statement following the webinar, officials from Southern California Edison said it will be several weeks before fuel transfers begin again.
“Now that the NRC has said fuel transfers can safely resume, Holtec crews are being remobilized and retrained and SCE has several weeks’ worth of internal reviews to perform before we are ready to announce a date for again moving spent nuclear fuel from wet to dry storage,” said Doug Bauder, SCE vice president and chief nuclear officer.
Howell said Edison will complete more training and equipment analysis before it resumes transfers.
