Canister storage at San Onofre
Dry canister storage at the San Onofre Nuclear Generating Station. Courtesy Southern California Edison

An opinion column posted Sept. 7 contains many errors of fact and omission regarding the safety of the decommissioning process at the San Onofre Nuclear Generating Station that must be addressed. The column focused on the safety of the canisters used to store spent nuclear fuel.

A statement regarding Cesium-137 and the Chernobyl accident ignores how it is released during an operating reactor accident. SONGS is no longer operating, of course. The cesium must be at an elevated temperature to form a plume that can travel offsite. SONGS’ fuel has cooled to the point at which the Cesium-137 is not hot enough to form a plume. In fact, Cesium-137 is not volatile at dry storage temperatures, so it remains encased in a ceramic fuel pellet.

If a spent nuclear fuel canister were to begin “degrading,” the risk of a release that would affect the health or safety of the public is vanishingly small. Even with a through-wall crack, the ceramic spent fuel pellets are still well-contained in sealed zirconium-alloy fuel rods. The robust shielding of the overall system remains as well. A microscopic crack would not release high levels of radiation any more than a small crack in your oven’s window would heat your home by hundreds of degrees.

The fact that the Nuclear Regulatory Commission has yet to evaluate nor approve a canister repair method does not mean the agency can’t or won’t in the future. In this area, Southern California Edison is leading the industry. Spent nuclear fuel has been stored safely for 35 years in the United States without the need for repair. The only canisters ever needing to be returned to a spent fuel pool were bolted-lid casks advocated in the Sept. 7 column. Those thick-wall casks have mechanical seals, not welds, and those O-ring seals may need to be replaced. In the United States, 93% of the canisters used today are the welded-lid, stainless steel canisters used at SONGS.

The column called the dry fuel storage canisters “inferior,” but offered no factual evidence to support the claim. The Department of Energy encouraged the industry to develop welded-lid, multipurpose canisters for storage and transportation, and the industry responded with systems that have, thus far, a zero failure rate.

The 2019 report from the Nuclear Waste Transportation Review Board was also mischaracterized in the column. The SONGS Community Engagement Panel hosted a NWTRB representative at its November 2019, meeting. The representative specifically said the NWTRB did not suggest spent fuel from nuclear plants, including SONGS, would need to be repackaged. Currently, more than 80% of the spent nuclear fuel at SONGS is eligible for transportation, if a federally licensed site was available for relocation.

Regarding canister lifespan, the warranty is 10 years on the Holtec system and 25 years on the canisters. But the design life is 60 years and the service life, or how long the canister can perform its safety function, is 100 years or more. Those are key numbers omitted in the column.

The “16-years” through-wall crack fallacy stems from an error in a presentation six years ago referring to a water tank at South Africa’s Koeberg Nuclear Plant. A recent report by the Electric Power Research Institute corrected the original error. The NRC has weighed in on this issue, explaining that in a marine climate like California, a through-wall crack in a canister would take 80 years to occur, if no action were taken to mitigate it.

Calling for a “hot cell” and reloading fuel into thick-wall casks is not a well-reasoned recommendation. No dry storage canister has ever released radioactive material to the environment, and there’s no indication canister failure is even remotely imminent. Reloading 3,885 fuel assemblies from dry storage canisters to thick-wall casks would only introduce additional risk with no obvious benefit.

Spent nuclear fuel is stored safely in the United States. Where attention needs to focus is on finding long-term storage or disposal solutions. We are now more than 20 years past the date when the DOE was to begin picking up spent fuel from nuclear sites around the country. If we want the fuel moved once and for all out of Southern California, we need advocates for federal action, armed with facts.

John Dobken
Public Information Officer
San Onofre Nuclear Generating Station

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