Holtec International, the company making canisters to contain highly radioactive nuclear waste at San Onofre, has escaped fines related to the surprise redesign of those vessels, which caught officials at Southern California Edison and the Nuclear Regulatory Commission off guard.

Part of the reason: San Onofre’s spent fuel is not so hot.

An investigation revealed that Holtec altered the canister design — adding pins to the canister bottoms to facilitate the flow of cooling gas — without permission from the NRC. Holtec considered the change too minor to require NRC scrutiny; the commission disagreed.

“The failure to establish adequate design control measures and obtain NRC approval prior to modifying multi-purpose canisters with four-inch, stainless steel stand-off pins, was deemed potentially safety significant,” the NRC said in its final decision on the matter, released last week.

“Holtec’s design review process for the change did not adequately consider all potential impacts that could adversely affect the safety-related functions. …. The stand-off pins are essential to the function of the fuel basket to maintain support and ensure that the shims remain in place to allow helium to adequately circulate around the fuel assemblies within the canister.”

But the NRC essentially said no harm, no foul.

The waste loaded into four Holtec canisters with the new, unapproved design at the shuttered San Onofre Nuclear Generating Station had been cooling in spent fuel pools for years, and, thus, is not as hot as what the canisters were designed to withstand. That means that even if pins broke — impeding gas flow inside the canister — it wouldn’t pose a safety problem.

However, if the canisters had been loaded with hotter fuel, the failure of multiple pins “could have compromised the heat transfer characteristics,” increasing temperatures inside the canister beyond allowable limits and potentially damaging insulation material, the NRC said.

Holtec had two violations, the NRC said: failure to establish adequate design control measures of components important to safety, and failure to perform evaluations before making changes.

A base civil penalty of $36,250 was considered and rejected due to Holtec’s “prompt and comprehensive” corrective actions, which included the elimination of the pin design; a “lessons learned assessment;” and revised engineering protocols.

That outraged some critics. “The failure by the NRC to fine Holtec for breaking the law shows that it isn’t serious about protecting the public’s safety,” said Charles Langley, executive director of Public Watchdogs, in a statement.

Joy Russell, Holtec’s senior vice president of business development and communications, said the NRC has confirmed the safety of the canisters with the pin design and that the canisters “would continue to be in a safe condition during the entire licensed period of storage” and “did not result in an actual significant safety concern.”

“The loaded canisters do not and never have posed any risk to public health and safety,” Russell said in a statement. “Holtec accepts the violations and … the NRC has determined that Holtec’s violations resulted in having moderate to low safety significance concern. Holtec remains committed to safety in all we do and will continue to work with the NRC.”

Updated 4.30.2019 with statement from Holtec

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