(CN) – The Nuclear Regulatory Commission held a hearing Wednesday to discuss whether to implement penalties against Holtec International, the manufacturer of a faulty nuclear waste canister buried at the shuttered San Onofre Nuclear Generating Station.
The San Onofre Nuclear Generating Station, or SONGS, is located along the coast in San Clemente, California, 60 miles north of downtown San Diego. It closed in 2012 after radioactive reactor coolant leaked from an 11-month-old steam generator.
Last year, the decommissioning process to bury cooled, spent nuclear waste in stainless steel canisters on the beach next to the shuttered nuclear plant began – but the process did not unfold smoothly.
In March, workers inspecting a canister during a pre-loading inspection discovered a four-inch stainless steel pin, known as a shim standoff, loose on one of the Holtec canisters.
The company changed the design of its canisters in 2016 so that helium within the canister could circulate around the nuclear waste canister to keep it cool, which included the shim standoffs. Holtec considered the design change minor enough not to notify the NRC.
But the NRC found the lack of notification a violation of its rules.
At the public meeting live-streamed from NRC headquarters in Maryland Wednesday, Michael Layton, director of the Division of Spent Fuel Management for the NRC, said the commission “does not believe there is an imminent safety threat with the canisters that are currently loaded with the pins.”
Advocates for nuclear waste safety said the March incident, in addition to another from August in which an improperly loaded cask was emanating higher-than-expected radiation levels, indicates that Holtec is not properly handling the volatile nuclear waste.
The Occupational Safety and Health Administration industrial safety worker who blew the whistle on the August incident revealed that Holtec workers nearly dropped one of the loaded nuclear waste canisters 18 feet while lowering it into an enclosure after the canister got caught on an inner ring of the enclosure container.
The August incident prompted nuclear waste cannister transfers to be suspended pending an inspection by the NRC.
Wednesday’s hearing was Holtec’s last opportunity to share any pertinent information with the NRC about its canisters and its response to the breach last year before the NRC decides whether to implement penalties or corrective action.
Dr. Kris Singh, Holtec’s president and CEO, gave a lengthy presentation to NRC officials in which he insisted the faulty shim standoffs do not compromise the safety of the nuclear waste canisters and that the ones loaded with nuclear waste “can fulfill their intended function.”
Singh said only 1 of 88 shim standoffs used in nuclear waste canisters at SONGS failed, which he said “was not a widespread failure.”
“They are minuscule in their presence and, as it turns out, minuscule in their significance as well,” Singh said.
Holtec has checked 4,200 shim standoffs in its containers, finding 0.12 percent were broken, while 1.22 percent sustained a “slight bend,” according to Singh.
A test by Holtec assuming all the shim standoffs failed found the loaded nuclear waste canisters would still function according to regulatory limits, Singh added.
Despite noting the shim standoffs “play no role” in the safety function of the canisters, Singh said Holtec has made improvements to prevent damage of the nuclear waste equipment during handling and transport to the site, including abandoning the 2016 design changes that he said were implemented out of “technological greed” because they were easier to fabricate.
Throughout the hearing, Singh placed some of the blame on “industry inadequacies” in manufacturing and design.
“We did not foresee the problem – I readily admit to you, we did not see our limitation. This was definitely an eye opener for us; we have learned how to treat manufacturing evolutions more respectfully,” Singh said.
The NRC expects to release its final decision from the hearing within 30 to 60 days.