The test canister at San Onofre Nuclear Generating Station had two “mock” defects, like pock marks on its outer skin. It was heated up to mimic the temperature of a real canister loaded with nuclear waste.
Then the repair robots — sort of like high-tech St. Bernards — were sent into the vault to find and fix them.
One robot carried inspection cameras. The other, a nozzle mounted on a movable arm. Using magnetic wheels to crawl around, they found the trouble spots and applied a metallic overlay of nickel, effectively sealing them, said Southern California Edison in a video posted in advance of its quarterly Community Engagement Panel meeting on Thursday, May 28.
This screenshot from a Southern California Edison video shows robots on a repair mission to fix a mock canister at San Onofre.“The demonstration performed at SONGS brought together state-of-the-art inspection and repair technologies to implement a repair of a potentially degraded canister installed in its storage vault,” Edison says in the video on the experiment. “SCE further demonstrated the process is deploy-able, reliable and capable of implementation on any canister installed at SONGS.”
Skeptics have long feared otherwise. Many canisters were scratched as they descended into their dry-storage vaults at San Onofre, and some fear those scratches will grow into cracks that undermine the canisters’ integrity as the years go by, ushering in what could be doomsday scenarios.
These critics have demanded that Edison keep a spent fuel pool on site to fix such damage, but Edison has said that approach is dated and unnecessary due to advances in technology. The demonstration of the robotic repair is meant to assuage those concerns, but many remain deeply distrustful of the company and are unlikely to be mollified.
This screenshot from a Southern California Edison video shows a sample that has been coated with nickel.Experts will be on hand at the community meeting to discuss “outlier” scenarios — “highly unlikely events” such as terrorism, sabotage and canister degradation over time, Edison said.
“We must prepare for the possibility that the spent fuel will be here for some time — maybe decades,” wrote David Victor, chair of the panel and co-director of UC San Diego’s Laboratory on International Law and Regulation. “In that context, the CEP has devoted at least one meeting per year to the topic of ‘defense‐in‐depth’ … to understand the layers of design, fabrication, monitoring, remediation/repair and other activities that, together, give confidence in the integrity and safety of” San Onofre’s dry storage systems.
“We have also been getting questions about what, even with robust defense‐in‐depth, are some of the worst things that might happen …? If they happen, what might be the consequences and responses?”
The Holtec Hi-Storm Umax dry storage system for spent fuel at San Onofre Nuclear Generating Station. (Courtesy Southern California Edison)The dry fuel storage systems at San Onofre are designed to withstand outlier scenarios, Edison said.
The San Onofre Community Engagement Panel is a group of locals advising Edison on the plant’s tear-down, and its meetings have been the site of many a fiery exchange.
This meeting will be online due to the COVID-19 pandemic, and will also include updates on San Onofre’s deconstruction, including what’s happening inside those containment domes; the results of monthly radiation monitoring; and an update on fuel transfer operations.
To date, 63 of 73 spent fuel canisters have been transferred from cooling pools to the Holtec dry storage system, and all waste will be out of the pools by summer. That’s a major milestone: Experts say dry storage is safer than pools because it’s passive, meaning it doesn’t require electricity or water to keep the fuel cool.
Edison also is working on a strategic plan to explore the possibility of moving spent fuel off the bluff over the Pacific, and expects to finish by the end of the year.
The meeting begins at 5:30 p.m. Thursday. A link to the video conference will be at songscommunity.com.
After decades, the heart of a nuclear reactor will finally leave San Onofre
Updated 5.24 p.m. 5/26 with latest canister numbers