Answers to Questions About Decommissioning

The following is a Q&A with Tom Palmisano, Vice President, Decommissioning, and Chief Nuclear Officer, San Onofre Nuclear Generating Station.

Updated 3/8/18

Since Southern California Edison (SCE) announced in June 2013 it would permanently retire the San Onofre nuclear plant, significant progress has been made on preparations to decommission the plant. We sat down with Tom Palmisano, SCE's Vice President of Decommissioning and Chief Nuclear Officer, for an update on decommissioning.

Q: What is the status of San Onofre decommissioning?

A: Safety remains our highest priority as we take steps to decommission San Onofre. We have completed a significant number of submittals to the Nuclear Regulatory Commission (NRC), including a decommissioning plan, cost estimate, environmental report and fuel management plan. In addition, Southern California Edison (SCE) and the San Onofre co-owners announced three core principles that will guide the decommissioning process: safety, stewardship and engagement. We also want to make sure decommissioning proceeds in an inclusive and forward-thinking way, with input from a broad range of stakeholders. That is why we created a Community Engagement Panel to advise us on decommissioning. This panel holds public meetings at least quarterly in communities near San Onofre and encourages public involvement.

Q: How long will decommissioning take?


A: The NRC requires that nuclear plants be decommissioned within 60 years. We intend to dismantle and decommission San Onofre Units 2 and 3 near term. When we factor in up-front planning time, we expect decommissioning of San Onofre can be completed in approximately 20 years.

Q: Who pays for decommissioning and how much will it cost?

A: Decommissioning San Onofre is expected to cost $4.4 billion. The project is paid for with trust funds that were established early during the plant's operations. Based on forecasted escalation, the trust funds are fully funded. Customers contributed about one-third to the trust funds and the remaining two-thirds are earnings from investments overseen by a five-member board.

Q: What's next?

A: We are continuing preparations to ensure plant equipment is de-energized and ready for dismantlement work, which may begin by late 2017, subject to regulatory approvals.

Q: Are there state environmental reviews for decommissioning San Onofre in addition to the federal reviews?

A: The California State Lands Commission will serve as the lead agency for the California Environmental Quality Act (CEQA) review for San Onofre decommissioning. This process began in November 2015 and is expected to continue through 2018 including opportunities for public comment.

Q: What will happen to the used nuclear fuel at San Onofre?

A: We will continue to safely store used fuel on site, as we have for more than 30 years, following best industry practices and subject to ongoing NRC oversight. San Onofre's safe and secure storage uses a combination of technologies: enclosed, steel-lined concrete pools filled with water (spent fuel pools) and sealed stainless steel canisters housed in reinforced concrete structures (dry cask storage). The California Coastal Commission in 2015 approved a Coastal Development Permit that enables us to expand dry storage of used nuclear fuel at San Onofre. We intend to move all of the used nuclear fuel into dry cask storage by 2019. Storage in canisters is a key step as it also facilitates transfer of used nuclear fuel to an off-site storage facility. We maintain on-site security measures at San Onofre, as required by the NRC, to protect the health and safety of employees and the public.

Q: Will used nuclear fuel remain at the San Onofre site even after decommissioning is completed?

A: Interim storage at nuclear plants such as San Onofre is necessary because the federal government failed to fulfill its contractual obligations to open a permanent spent nuclear fuel repository. SCE, like other nuclear plant operators, successfully sued the federal government for this failure. SCE received $112 million from the federal government, and has refunded the majority of the amount to customers. In addition, SCE, the San Onofre Community Engagement Panel and a number of community stakeholders have aligned to support proposals to create interim storage facilities for used nuclear fuel in Texas and New Mexico.

Q: How much used nuclear fuel is stored at San Onofre?

A: The uranium pellets that were used to generate power are in sealed fuel rods that comprise a used fuel assembly. San Onofre has 2,668 fuel assemblies in spent fuel pools in Units 2 and 3 and about 800 Unit 2 and 3 assemblies in dry storage. In addition, there are about 400 Unit 1 used fuel assemblies in dry storage. Combined, that's a total of 1,609 metric tons of used nuclear fuel at San Onofre.

Q: How does the court ruling on the NRC's "Waste Confidence Rule" – now called "Continued Storage of Spent Nuclear Fuel Rule" -- affect San Onofre?

A: In August 2014, the NRC issued a final rule on continued spent fuel storage and terminated a two-year suspension on related licensing actions for nuclear plants. The NRC's new rule renames waste confidence "Continued Storage of Spent Nuclear Fuel Rule." The rule adopted by the NRC concludes that used nuclear fuel can be safely stored in dry casks for a short term defined as 60 years, for a long term defined as 100 years and for indefinite periods.

As a practical matter, we don't expect the ruling to affect San Onofre decommissioning as it primarily affects plants seeking to renew their operating license or new plants seeking an operating license. We believe the ruling affirms our plans to safely store used nuclear fuel at San Onofre until the federal government takes title to and removes the fuel from site, as required.

Q: Does San Onofre have high burn-up nuclear fuel and, if so, how does that affect the way you store this used fuel?

A: Like many other nuclear plants, San Onofre took advantage of improvements in fuel technologies that allow nuclear plants to extract more energy from the fuel by achieving higher burn-up levels. SCE is licensed to use this fuel and store it in the spent fuel pool, and our dry storage canisters are licensed separately to store high burn-up fuel. Once this fuel is removed from the reactor, it is stored in accordance with NRC regulations and in the same manner as San Onofre's other used fuel - initially in a steel-lined, concrete spent fuel pool and later in dry cask storage.

Q: Do you continue to have emergency preparedness plans in case there's a radiological problem at San Onofre?

A: The NRC approved a revised emergency plan for San Onofre in June 2015 that reflects the reduced risk at a permanently shutdown nuclear plant. Most potential accidents related to an operating plant are no longer possible at shutdown nuclear plants such as San Onofre where fuel has been removed from the reactor. However, the revised emergency plan maintains many of our prior operating emergency planning elements, including: around-the-clock, trained emergency personnel on site to address unanticipated events; radiological and environmental monitoring; drills and close coordination with off-site agencies.

Q: What happens to the land at San Onofre after the nuclear plant is dismantled?

A: SCE leases the San Onofre land from the Navy and will return to it the Navy once decommissioning is complete, subject to NRC approval. Once San Onofre's license has been terminated and the NRC has released the site for unrestricted use, the area can be used in any way permissible by federal, state and local laws.

Q: How can the public learn more about the latest developments regarding the decommissioning of San Onofre?

A: This website,, is the best resource for anyone seeking regular updates on San Onofre decommissioning. Our Community Engagement Panel holds quarterly meetings that are open to the public and materials discussed at those meetings, as well as videos of the CEP meetings, are available here. In addition, Southern California Edison offers public tours of San Onofre. Citizens may also sign up on our website for email updates regarding San Onofre.

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