What the San Onofre Nuclear Generating Station looks like with demolition at 80%

Five years down, about three more to go to complete the dismantlement of the San Onofre Nuclear Generating Station.

“When we started in 2020, we said it would be about eight years,” said Ron Pontes, Environmental Oversight and Site Closure Manager for Southern California Edison. “We’re really on track with that, moving right along.”

Drivers zooming along Interstate 5 still see the two giant containment domes that rise 190 feet high at the site of the plant, known as SONGS for short. But a recent tour showed the Union-Tribune the extent of the massive deconstruction effort.

Nearly all of the above-ground structures are gone and piles of rubble, almost reminiscent of old photos of bombed out buildings from World War II, lie scattered around the scene as workers — some operating excavators and other heavy equipment — busily remove chunks of debris from the 84-acre footprint of SONGS.

“We’re about 80% done with this phase,” Pontes said.

Demolition efforts on the $4.7 billion project started in October 2020 and are scheduled to wrap up by the end of 2028.

By the time work is completed, about 1.1 billion pounds of equipment, components, rebar, concrete, steel and titanium will be removed. About 80% of the material is presumed to be radioactive.

SONGS has a railroad spur on site and most of the rubble gets shipped by railcars to a disposal facility in Clive, Utah. The vast majority of the material is labeled as Class A waste, the lowest level of radioactive material.

Class B and C low-level waste have already been removed, with non-radioactive material sent to Las Vegas for recycling or to a landfill facility in Arizona.

By the time the dismantlement wraps up, about 5,500 shipments will be made. Thus far, roughly 570 million pounds have left San Onofre in about 2,400 shipments.

Rail exports are monitored by the U.S. Nuclear Regulatory Commission and the Department of Transportation. A host of local, state and federal agencies that include the San Diego Regional Water Quality Control Board, the state’s Department of Toxic Substances Control and the U.S. Environmental Protection Administration also conduct environmental and building inspections.

“We’re definitely well-regulated,” Pontes said.

When will the domes come down?

The two containment towers will not come down all at once; there won’t be any dramatic implosions.

Rather, each dome will be reduced gradually, from the bottom up. Workers using hydraulic hammers will chip away at the 160-foot-wide circumference and, in stages, each dome will collapse onto itself, about 8 feet at a time.

“The weight of the building, gravity, works for you,” Pontes said. “Eventually it just settles and then you muck out all the concrete and rebar and do it again in 6, 8, 10-foot lifts, just hammering away at the side of it.”

The Unit 3 containment dome will come down first, with operations scheduled to begin in the fourth quarter of next year. Unit 3 is on the southern end of the plant, nearer to San Diego.

Once Unit 3 is gone, work on Unit 2 will begin. It takes about eight months to bring down each dome, so the timeline predicts that by December 2027, both domes will be gone.

“They are iconic, everybody sees them,” Pontes said. “So (their demolition is) going to have some obvious visual impact to people who travel on the freeway. Going to lose that marker, right?”

What’s inside the domes now

Large components inside Units 2 and 3 have been removed. That includes steam generators, pumps and pressurizers. They are now in the process of being demolished, with the debris going into railcars to be shipped away.

What remains in each unit is a reactor vessel — thick steel containers that held nuclear fuel in the reactor core and provided one of several barriers to keep radioactive material out of the environment.

The vessel in each unit needs to be segmented and removed. That work is nearly complete in Unit 3 and about to start in Unit 2.

With the steel in the reactor vessels from 9 to 12 inches thick, workers take them apart using a torch.

“We actually unfastened a reactor vessel from its support and lifted it with an internal tool that was built,” Pontes said. “We lift it up a little bit, we’re able to turn it and we’ve got a torch that’s stationary. As you turn the reactor vessel, it cuts it into small segments.”

The chunks go to the disposal site in Utah.

Pontes said the project at SONGS was informed by efforts at other nuclear plants across the country, such as Zion Nuclear Power Station in Illinois that took about 10 years. It employed a “rip and ship” process.

“It’s really a brute force approach, to break the plant up into literally smaller and smaller chunks so you have manageable waste streams that can be transported out of here,” Pontes said.

Perhaps the starkest representation of the project comes from a photo taken Aug. 6, 2024, showing the inside of the SONGS control room — what used to be the nerve center of the power plant — just before it was completely demolished.

Not completely done by 2028

SONGS stopped producing power in 2012 after a leak in a steam generator led to the plant’s closure.

While the demolition efforts in San Onofre are expected to wrap up in about three years, dismantlement does not mean SONGS has been decommissioned.

There are still a pair of dry storage facilities on the facility’s north end, housing canisters filled with 3.55 million pounds of nuclear waste.

One storage facility contains 73 stainless steel canisters containing spent fuel that have been lowered into vertical cavities. The other holds 50 canisters that are stacked horizontally.

Another 13 canisters of material from the dismantlement that classified as greater than Class C waste sit in the horizontal storage site.

The canisters rest a little more than 100 feet from the Pacific, protected by a seawall.

Until there’s a place to send them, SONGS will not be considered fully decommissioned.

Charles Langley, executive director at La Mesa-based Public Watchdogs and longtime nuclear power critic, said his group has more anxiety about the canisters at SONGS than about Edison’s dismantlement efforts.

“They’re engineers. They ought to be able to take stuff apart as well as they can build it,” Langley said. “We just wish they had engineered a better solution for the nuclear waste and, unfortunately, there aren’t any easy solutions.”

Langley and others have expressed worry about the stainless steel canisters remaining so close to the ocean for years on end.

“Our concerns are almost exclusively with the nuclear waste,” Langley said, “because it’s eternally deadly.”

The canisters stay parked at SONGS — just as they are at other nuclear sites across the U.S. — because the federal government has yet to find a place to store the roughly 91,000 metric tons of spent fuel that has accumulated over the years at commercial facilities.

Yucca Mountain in Nevada had been slated as a permanent waste site but the Obama administration cut off funding for Yucca in 2010, after years of protests from lawmakers in the Silver State who had long opposed the project.

With Yucca off the table, federal officials have gone back to the drawing board, looking at potential sites to accept some or all of the waste, either on an interim (still-to-be-determined period) or permanent basis.

Edison officials have long insisted that the canisters at SONGS are robust and can withstand events that include rising sea levels, earthquakes and tsunamis.

“We generated that spent nuclear fuel due to the operation of the plant,” Pontes said. “It’s our responsibility to take good care of it, and we’re going to fulfill that responsibility … Now the federal government will eventually solve this problem. I just don’t know when it’s going to happen. It will happen. (The waste at SONGS) is safely stored where it is.”

Once the demolition work is finished, all that is expected to remain at SONGS will be two dry storage facilities; a security building with personnel to look over the waste; a seawall 28 feet high, as measured at average low tide at San Onofre Beach; a walkway connecting two beaches north and south of the plant, and a switchyard with power lines.

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

The $4.7 billion spent to dismantle SONGS will be paid from a decommissioning fund collected through rates paid by Southern California Edison and San Diego Gas & Electric customers when the power plant produced electricity.