Edison acknowledges its problems with nuclear waste loading at San Onofre, but ready to move forward

Executives from Southern California Edison did a mea culpa with the Nuclear Regulatory Commission on Thursday, Jan. 24, acknowledging that its managers failed to recognize the complexity and risks inherent in moving more than 70 nuclear waste canisters from wet to dry storage at San Onofre last year.

Now that those problems have been addressed, Edison told the NRC, it’s ready to get back to business.

In a public meeting broadcast via webinar, Edison dissected events leading to — and actions resulting from — the Aug. 3 “near miss,” when a 50-ton canister filled with radioactive waste got stuck on a shield ring near the top of the 18-foot vault where it was to be entombed. The slings supporting the canister’s massive weight went slack, and it hung unsupported for close to an hour, in danger of dropping.

The canister may have scratches as a result of contact with that shield ring — but calculations suggest scratches are “no more than the thickness of a couple of sheets of paper, at the worst,” said Jerry Stephenson, engineering manager for Edison.

NRC staffers expressed concerns about the possible long-term impact of those scratches, and about how management could have failed to recognize the overall complexity and risks of the fuel-loading operation to begin with.

Edison froze fuel loading operations immediately after the incident, and the NRC sent a special inspection team in September to figure out what was happening. The NRC laid blame squarely at Edison’s feet in November, saying it “fell asleep at the switch” and concluding that the near-drop was the result of inadequate training, oversight and supervision.

Thursday’s meeting was a “predecisional enforcement conference,” meant to get Edison’s input before the NRC makes final decisions on violations and penalties.

Scratch concerns

“The scratch analysis is based on engineering judgment,” said the NRC’s Linda Howell. “According to information given to us by SCE, it’s not uncommon for canisters to come in contact with shield rings, even when well-aligned when lowered. What gives you confidence that the calculations you’ve done are really and truly representative of the canisters already downloaded? Is there any additional physical testing to make sure those and future canisters are within manufacturing tolerances?”

Stephenson said Edison’s calculations were very conservative, and that nothing has been done to mitigate scratches because “they are so minor in the first place.”

Both Doug Bauder and Tom Palmisano — Edison’s vice president of decommissioning and vice president of external engagement, respectively — piped in, saying that while contact with shield rings may have caused minor scratches to canisters already loaded into the Holtec Hi-Storm UMAX dry storage system, scratches don’t pose any short-term issues and will soon be evaluated.

An inspection-and-maintenance program for the canisters is being developed and a plan is due in 2020. That system may use mini-robots equipped with cameras that crawl down into the vaults and examine the canisters up close.

NRC staff members, however, still appeared concerned. “We may have additional questions regarding the scratch analysis,” Howell said.

Complexity of operation

In the past, fuel transfers at San Onofre involved five or 10 canisters, loaded over a relatively short period of time.

In this operation, however, Edison faced loading more than 70 canisters over a period of about two years, with a new system design. It hadn’t anticipated the turnover of experienced technicians and it didn’t keep a close enough eye on contractor Holtec, executives told the NRC.

But there was no drop, no breach of the canister, no release of radioactive material. And even if the canister had fallen, it would have remained intact and there would have been no radioactive release, its analysis found.

Edison detailed all the changes it has made to beef up training and oversight. Cameras — to be monitored by many eyes — will watch as the canisters descend into dry storage vaults. Alarms will go off if there’s a sudden, significant change in the weight supported by the canister-lowering machinery. Workers will be more rigorously trained at loading canisters into the system, and management will be more “intrusively engaged.”

Additional people have been hired, and executives have been on hand to oversee dry-runs in recent weeks, where the newly trained teams practiced loading empty canisters into the vaults.

“SCE is focused on demonstrating these improvements are effective and sustainable during upcoming NRC onsite inspections,” the company said in a statement after the meeting. “The safe transfer and storage of spent nuclear fuel remains our top priority. It is important to note this event never impacted the health and safety of employees or the public.”

About 400 people tuned in to the webinar, and some skeptics remained unsatisfied.

“Regulators consider allowing loading of highly radioactive nuclear fuel waste into Holtec thin-wallstorage canisters at San Onofre to resume despite warnings that the storage canisters are likelydamaged by the Holtec loading system,” said a statement by activist Donna Gilmore of SanOnofreSafety.org, who calls the entire Holtec system defective.

Forty-four canisters remain to be loaded, and it appears likely they also will be damaged. “Confirming the degree of damage seems impossible, however, because the canisters cannot be inspected — much less repaired — once they are loaded into the dry storage vault.”

The NRC’s final decision is expected within 45 days.