Seven years after the San Onofre Nuclear Generating Station officially went offline, the eight-year process of physically dismantling the plant and knocking down the domes that have loomed over the landscape of Camp Pendleton for four decades is about to begin.

The plant’s operator, Southern California Edison, has mailed notices to about 12,000 residents in a five-mile radius of the plant that initial work will start no earlier than Feb. 22. The first jobs include erecting staging areas and temporary trailers in the plant’s parking lots and removing materials containing asbestos in the Units 2 and 3 domes.

By the time work is complete, all that will remain will be two dry storage facilities housing canisters of used-up nuclear fuel from the days when the plant still produced electricity, a security building with personnel to look over the waste enclosed in casks, a seawall 28 to 30 feet high, a walkway connecting two beaches north and south of the plant and a switch-yard with power lines.

The substation without transformers stays put because it houses electricity infrastructure that provides a key interconnection for the region’s power grid.


Southern California Edison officials say they will expand rail capabilities on the site to reduce the use of trucks around the project in the hopes of reducing traffic congestion.

“To the extent possible, we’ll schedule and perform our work to minimize any inconveniences to you and your neighbors,” Doug Bauder, the chief nuclear officer at SONGS, said in the notice sent earlier this week.

The twin domes, rising 200 feet between Interstate 5 and the Pacific, are expected to come down in mid- to late 2025.


Away from the plant’s immediate footprint, the project will also get rid of offshore buoys and anchors and partially remove the large pipes that sucked in and then discharged ocean water in order to cool the plant.

The costs for the dismantlement will come from $4.4 billion in existing decommissioning trust funds. The money has been collected from the plant’s customers and invested in dedicated trusts. According to Edison, customers have contributed about one-third of the trust funds while the remaining two-thirds has come from returns on investments made by the company.

Getting rid of the pools

The work comes after Southern California Edison, or SCE, received approval to proceed last year from the State Lands Commission and then from the California Coastal Commission.


But the decisions were not without controversy. A number of critics of SCE’s management of the plant argued against granting the permits. One of their major concerns centered on the demolition of two spent fuel pools where used-up nuclear waste goes to be cooled.

Electrical cables brought into the Unit 2 containment dome at the San Onofre Nuclear Generating Station in preparation for efforts to begin dismantling the plant. (Photo from Southern California Edison)

While fuel inside a nuclear reactor typically loses its efficiency after about four to six years, it is still thermally hot and emits a great deal of radiation. To keep the fuel cool, nuclear plant operators place the used-up waste in a metal rack and lower it into a deep pool of water , typically for at least five years. Once cooled, the fuel is often transferred to a dry storage facility.

The Nuclear Regulatory Commission does not require operators to maintain the pools but many local environmental groups and critics of the plant say the wet storage option should remain.


The San Clemente-based Surfrider Foundation wants SCE to keep at least one spent fuel pool in place, or at least have a “readily deployable on-site repair device at the ready, in case a canister is damaged and needs to be retrieved.

“If canister integrity gets compromised in this coastal and corrosive environment, there needs to be a mechanism to repackage or repair it,” Mandy Sackett, Surfrider’s California policy coordinator, said in an email.

SCE officials say sending a damaged canister back to a pool poses more risks in terms of increased radiation dose to workers, potential radiation releases or damage to fuel rods than repairing the canister by using a metallic overlay or putting the canister into a licensed cask that can be transported.

“It would also be difficult to dismantle some of the structures and fully decommission the site if we had to maintain a working spent fuel pool,” SCE spokesman John Dobken told the Union-Tribune last fall.

In an agreement with the Coastal Commission, SCE has pledged to develop an inspection and maintenance plan for the canisters holding used-up fuel that goes into what is called a “dry storage” facility at the plant. The company will also pay for an independent, third party to review the plan, which will be forwarded to the commission’s staff.

By this July, the Coastal Commission is expected to consider a recommendation reached by its staff about whether to approve the plan. SCE cannot begin removing the spent fuel pools until then.



Dismantling the pools is anticipated to start late next year and continue for several more before work is completely finished.


The water will be cleaned, sampled and, according to SCE’s Dobken, “once we ensure it meets our strict regulatory requirements, it will be released to the ocean through conduits that carry it 1.1 miles offshore, 50 feet below the surface.” Dobken said the radioactivity of the water will be “at very low levels that meet strict regulatory guidelines when released.”

What happens to rest of the stuff?

As for the tons of steel and concrete that made up the plant, they will be shipped to various facilities in the West and buried.

Low-level radioactive waste will move via rail to a disposal site in the desert near Clive, Utah, and higher-level waste will be sent by rail or truck to a private storage facility in West Texas. Non-radiological waste will be trucked to a land fill in La Paz County, Arizona.


The U.S. Nuclear Regulatory Commission’s oversight includes the decommissioning of commercial nuclear power plants and the agency will perform periodic inspections of San Onofre’s dismantlement. The State Lands Commission will also conduct inspections.

Dismantlement of the plant will be carried out by a general contractor selected in December 2016 — a joint venture of AECOM and Energy Solutions called SONGS Decommissioning Solutions.

While the plant has not been producing electricity for the past eight years, transfers of used-up fuel from the “wet storage” pools to a newly constructed “dry storage” facility at the plant continue. The first seven months of the dismantling will run at the same time that 50-ton canisters loaded with the waste are slowly moved using heavy equipment and eventually lowered into their respective storage cavities.

So far, 47 canisters have taken the trip to the north side of the plant, with 26 more coming. SCE officials expect to complete all the transfers by late this summer.

Dobken said until the transfers are completed, dismantlement work will focus on areas away from where the waste is being moved.

Transfers were suspended for nearly a year after a 50-ton canister filled with fuel assemblies came to rest on a metal flange, 18 feet from the floor of a storage cavity for about 45 minutes to an hour in August 2018. The canister, left unsupported by the rigging and lifting equipment intended to shoulder its weight, was eventually lowered without falling.


News of the incident came to light after an industrial safety worker disclosed details at a public meeting six days later and prompted a special inspection by the NRC.

Pre-dismantlement work at the San Onofre Nuclear Generating Station. (Photo by Southern California Edison)

The regulator concluded that SCE failed “to establish a rigorous process to ensure adequate procedures, training and oversight guidance” and fined the company $116,000 in March of 2019.

Vowing to avoid another “near-miss,” SCE officials instituted a series of more robust measures to transfer waste at the site.


But the incident — along with the leak in a steam generator tube in 2012 that led to the closing of the plant — has led some to question how effectively SCE can conduct the decommissioning project. And the fact that the canisters will almost certainly remain after the project is scheduled to be completed is cold comfort.

“My skepticism runs deep because I’ve seen what’s happened in the past,” said Gary Headrick, co-founder of the environmental group San Clemente Green. “I wish I could trust Edison but I don’t.”

Sackett, who said Surfrider will monitor the dismantlement “very closely,” said SCE “does seem like they are working to be more transparent, thorough and careful” in the aftermath of the August 2018 incident.

“We really hope that they will continue to act and dismantle in a way that takes into account public safety and they hold themselves accountable to an extremely high standard that protects public safety and the environment,” Sackett said.

All told, there are 3.55 million pounds of spent fuel at San Onofre. But the plant is far from the only facility with waste on its premises.


About 80,000 metric tons of used commercial fuel has accumulated at 121 sites in 35 states because the federal government has not found a repository where it can be stored. Federal authorities were supposed to begin taking custody of commercial nuclear waste in 1998.

The Yucca Mountain repository, a facility about 100 miles from Las Vegas, was supposed to open in 2020 to take the commercial spent fuel but the Obama administration took another look at the project and funding was eventually cut off. There has been talk on Capitol Hill of reviving the Yucca Mountain project, as well as sending commercial waste to what are called “interim storage facilities” in remote locations but nothing concrete has been agreed upon.

Originally licensed in 1967, San Onofre was carved out of an 85-acre chunk of Marine Corps Base Camp Pendleton, on property owned by the Department of the Navy. Under the terms of the contract, SCE will maintain the property as long as the spent fuel remains on site. Once the waste finds another home, the property will be returned to the Navy.