The U.S. Nuclear Regulatory Commission (NRC) stared over the engineers’ shoulders of Southern California Edison and Holtec International International as they studied the effects of scratches on eight fuel canisters at the San Onofre Nuclear Generating Station (SONGS).
This was part of the NRC’s review of Southern California Edison’s (SCE) and Holtec’s remedial work stemming from the Aug. 3. loading mishap at SONGS involving a 100,000-ton canister getting hung up on a shield ring while being inserted into a dry storage hole. That resulted in safety straps going slack, eliminating a major safety feature designed to prevent the canister of used nuclear fuel from falling 18 feet.
Spent nuclear movement at SONGS has been suspended for the past nine months as SCE and Holtec fixed procedural and training problems. Two weeks ago, the NRC gave approval for Holtec and SCE to resume movement when they are ready. But the two are still working on internal reviews prior to restarting movement.
At a Monday webinar on the NRC’s decision, Linda Howell, acting director of the NRC’s Region 4 division of nuclear material safety, speculated that the two might take a few weeks to finish their own internal work.
The question has arisen the past few months of whether people should worry about abrasions and scratches that have shown up on the canisters from moving and inserting them. Eight inserted canisters were analyzed. Howell said NRC inspectors were “standing side-by side” with Holtec and SCE experts during the data collection on seven of those canisters.
Also, the NRC double-checked the contractors’ calculations, concluding Holtec’s ’conclusion of no problems was “conservative.”
In response to questions submitted to the webinar, Howell said the casks have a 40-year design life. “There is ample evidence these would be safe for 50 years and beyond,” she said.
A comment emailed to the webinar criticized the NRC for having only a 40-year design life for the containers and not having a plan in place for dealing with breaches.
Howell said a breach is unlikely. If a breach occurs the contractor would be responsible for coming up with a plan to deal with the incident, with Howell speculating that a damaged canister would be likely put into an overpack.
