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Tom Palmisano
Tom Palmisano

By Tom Palmisano, Southern California Edison’s vice president of decommissioning and chief nuclear officer

I write to offer your readers important facts regarding the continued safe storage of used nuclear fuel at San Onofre nuclear plant, and to correct errors on this topic in a letter to the editor published in the April 1 edition of the San Clemente Times.
San Onofre nuclear plant stores one-third of its used nuclear fuel in licensed, regulated dry cask storage canisters. We plan to transfer the remaining two-thirds, currently in steel-lined concrete pools, to dry storage by 2019. Similar storage systems have been safely used for 30 years in the United States, and the Electric Power Research Institute (EPRI) projects it would take a minimum of 80 years before canisters like those at San Onofre might experience a crack.
The April 1 letter incorrectly interpreted a 2015 Sandia National Labs study, which reviewed and compared previously performed experimental “accelerated” corrosion rates, using conditions impossible to achieve in the natural environment of existing dry storage canisters.
The Nuclear Regulatory Commission (NRC) has reviewed the Sandia report, and noted the Sandia work included experimental corrosion studies intended to provide a basis to mitigate stress corrosion cracking on a new standardized canister. The study concluded that stress corrosion cracking may be possible within 150 years, the authors’ proposed regulatory lifetime of the new canister. The report does not conclude that corrosion could occur in very short time intervals in real-world conditions, as asserted in the letter to SC Times.
The dry storage canisters at San Onofre are initially licensed for 20-year periods by the NRC, which inspects the design, manufacture and use of dry casks to ensure adherence to safety and security requirements. The NRC conducts safety reviews prior to re-licensing canisters for 20- to 40-year periods.
Used nuclear fuel must be in canisters before it can be transferred from San Onofre to an off-site location, as proposed by numerous community and elected leaders. As long as fuel remains at San Onofre, Southern California Edison (SCE), majority owner of the plant, will continue to safely store and monitor it in accordance with NRC regulations. In addition, SCE will partner with the EPRI to apply leading-edge cask inspection techniques at San Onofre.
The California Coastal Commission appropriately approved, with conditions, SCE’s Coastal Development Permit to expand dry storage at San Onofre, based on issues within the commission’s jurisdiction.

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comments (6)

  • 10 / 20 a 150 years is all BS this is a 10 thousand year problem

    talk about job security ! how does the military deal with it ?

  • Was Edison being conservative when you approved the computer modeling done on the steam generators that failed at San Onofre? What if you are wrong again when it comes to safe storage containers? Do you have a realistic plan to implement if canisters begin leaking before they can be relocated, or do you excuse yourself by claiming it is too unlikely to take into consideration? These are serious questions that need to be answered. We can’t afford to make mistakes with so much at stake. Please don’t assume everything will go as planned. We know from several examples, especially from this industry, that they don’t.

    Here are some other factors for readers to consider…

    • oh but sce is to big to fail /////might not be corrosion but thermodynamics that will cause movement and fatigue and the canister will fail but not in these liers life time ..unless something like a big giant wave or a plane a meteor or a terrorist accelerate the process

    • @ Gary Headrick

      Were you being truthful when you claimed the Steam Generator tube leak at San Onofre almost resulted in an accident worse than Fukushima? How about the bogus claims you made to news gal Vikki Vargas? Or the picture of you attempting to hoodwink the public into believing the Units 2 & 3 sea wall isn’t the stated 30 feet when the picture of you was at Unit 1, the wrong unit?

      These are serious questions that need to be answered before anyone in the public should listen to your baloney.
      Before questioning others’ integrity, gain some yourself.

  • Tom,
    The majority of U.S. thin canisters have been in use less than 10 years as this chart with DOE inventory data shows.

    You cannot and have never inspected even the surface of these canisters so you have no idea if they have any cracks, let alone how far the cracks have penetrated the wall of the thin canisters. The Holtec canister CEO, Dr. Singh states even if you could find a crack, even a microscopic through wall crack will release millions of curies of radiation into the environment and it’s not feasible to repair cracks, even if you could find them. So it is misleading to say you can “monitor” these canisters. Monitoring is not inspecting. Your intermittent radiation monitoring will only alert you after it starts leaking radiation. Temperature or radiation monitoring is not going to solve the problem when one of these canisters leaks. You have no NRC approved plan in place to deal with a failed canister.

    Regarding the “within 150 years”. “Within” means 1 day to 149.99 years, so this is a fairly useless statement, but serves the purpose of being misleading.

    The NRC’s aging management plan is inadequate. It only requires inspection of one canister at the plant and only after 25 years in service with the hope that the nuclear industry will figure out how to inspect them. You also have no way to know what’s happening on the inside. Japan found that the aluminum baskets they use to hold the fuel assemblies may fail in 60 years. Since the thin canisters are welded shut, you have no way to inspect the condition of the fuel or the aluminum baskets.

    The Koeberg nuclear plant had a similar component to canisters (a waste water tank) leak in 17 years. The NRC considers this comparable to the thin spent fuel canisters. This was not a “hot container” and the Sandia Lab reports shows there is a correlation between heat and increased rate of crack growth. It’s common knowledge in the material engineering field that hotter stainless steel will cause cracks to grow faster. Just how fast is what is in dispute here.

    The EPRI report you referenced ignored the Koeberg data, ignored their own Diablo Canyon data that showed temperature on a 2-year old canister was in the range for salts to melt onto the canister. Salts were also found at Diablo and we have plenty of salt at San Onofre. That EPRI report also ignored the fact that at San Onofre we have frequent fog, on-shore winds and surf — just like the Koeberg environment. EPRI is a utility funded “research” institute, so I’m not surprised they cherry-picked the data to fit the desired conclusion.

    I wouldn’t buy a car that couldn’t be inspected, maintained, repaired, and had no warning system prior to failure. You’re taking all our families for a ride with these canisters and you know there are better options. Your reasoning that Areva didn’t bid the thick casks doesn’t hold water. Your bid specifications didn’t require the system be inspectable, maintainable, repairable and have an early warning system prior to a radiation release, so of course you received bids for inferior products. You know the thick casks could be procured in plenty of time to move the fuel out of the pool. It’s not like the fuel is going anywhere anytime soon. You still don’t have an NRC approves system. The Holtec system was approved as an underground system with 1/2″ thick canisters. Instead, you want to install it half underground, just stopping above the water table. There is no drain this system, so air vents will collect water and other particles. You have not addressed this issue. If this system is so great, why does the vendor only warrant it for 10 years for the infrastructure?

    And you haven’t mentioned the NRC doesn’t allow even partial cracks for transport. Or the fact if you use the 37-fuel assembly canisters, it will require up to 45 years before it’s cool enough to meet Dept of Transportation safety requirements.

    And you never mention the Coastal Commission special conditions that require you to be able to inspect, repair, maintain and transport this system, but only after 20 years. Or that you’re required to move these to higher ground if needed for coastal erosion, yet you have no funds allocated to do this in your decommissioning plan to the CPUC.

  • Here is a list of all dry storage canisters and casks in U.S., listed by State as of 6/30/2013. Information from the Department of Energy as reported by utilities.

    Here is an updated chart that more clearly showing how most canisters have been in use less than 10 years and provides some additional information.

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