Millions of pounds of spent nuclear fuel will remain in storage at the San Onofre Nuclear Generating Station for decades — and potentially much longer — raising concerns among experts about the long-term health and environmental risks of storing radioactive waste so close to San Diego.
The spent nuclear fuel provided power for two generations of Californians, but its resulting waste will remain hazardous for thousands of years, according to James Day, a professor of geosciences at the Scripps Institution of Oceanography.
“Nuclear power produces waste that goes for possibly as long as 2,000 generations,” Day said. “It’s my job to tell you that, geologically, we must be thinking long-term — generational. How do we use or remove waste that has produced over 40 years of energy?”
This waste was supposed to go somewhere else, but the federal government’s proposal to build an underground repository at Yucca Mountain in Nevada never materialized. The plan stalled in 2010 amid political, public, tribal and legal opposition. The bunker, under consideration since 1987 and costing an estimated $15 billion to develop, remains unbuilt.
Without a national repository, nuclear waste remains stored at 80 sites across the country with no clear timeline for removal. After the federal government failed to meet its obligation to take the waste, it has paid reactor owners about $9 billion in storage costs. Most power plants were not designed to store waste indefinitely.
San Onofre presents particular challenges for long-term storage. Kept in underground dry-storage vaults, 3.6 million pounds of spent nuclear fuel sits between Interstate 5 and the Pacific Ocean, roughly halfway between San Diego and Los Angeles. The location leaves the storage facility exposed to long-term concerns about coastal erosion, storms and earthquakes.
Rep. Mike Levin (D-CA), who lives just 10 minutes from the decommissioned power plant, says the US needs to stop and fix the storage issue before progressing with new nuclear technologies.
“It’s a symptom of a greater problem. There is no national solution for the nation’s spent nuclear fuel, we haven’t had one for a very long time,” Levin said. “I was one of around 35 or 40 members of Congress that said, explicitly, ‘Hold your horses here with the nuclear industry.’ We have to fix the back end of the fuel cycle. It’s got to be a national issue.”
Levin introduced the Bipartisan Nuclear Waste Administration Act, which would establish an independent Nuclear Waste Administration to manage the country’s nuclear waste. The bill was referred to the House Committee on Energy and Commerce in September 2024.
“Years of inaction have left nuclear waste stored in communities all across the country – including ours – and with the federal government currently spending $2 million per day for the failure to fulfill its obligation to find a real solution,” Levin wrote when he introduced the bill. “It’s clear that now is the time to act on bold solutions.”
Innovative solutions to the challenges at San Onofre could lay the groundwork for how the nation manages nuclear waste in the future.
Gregory Jaczko, former chairman of the Nuclear Regulatory Commission, describes San Onofre as a “test case” to see if the country can handle nuclear waste management. Jaczko joined Day, Levin and other experts across disciplines to discuss the storage problem at a seaside symposium hosted by the Samuel Lawrence Foundation at Scripps on Aug. 20.
“Of any site in the country, it is most significant to move fuel to a different location,” Jaczko said to the audience. “San Onofre is a racecar at the back of the field that’s about to get lapped by all these new technologies — a new nuclear renaissance, a new generation of power plants — and here we are, still, without any real solution for nuclear waste.”
Long-term storage risks
The power plant is positioned with little room between the Pacific Ocean and Interstate 5. For the speakers, storing waste in such close proximity to the water raises storm and coastal erosion concerns.
With El Niño on the horizon, sea levels along California’s coast could temporarily rise by as much as 13 inches, according to Scripps scientists. That, coupled with increased odds of powerful coastal storms, could threaten the beachfront facility, some experts at the symposium warned.
That’s not all. Earthquake fault lines are yet another threat to long-term storage.
Day explains that the San Onofre plant lies just a few miles from the Rose Canyon Fault Zone — the primary seismic hazard in San Diego county. According to him, those slow-moving geological risks must be considered when planning for waste that could remain hazardous in the long term. Geological studies estimate an average 700 years between each major earthquake on the Rose Canyon Fault.
“Hindsight is 20/20, but I never would have put a power plant in a place that is actually covered in faults,” Day said. “The San Onofre power plant is rated to a magnitude 7, but it’s never been tested.”
Local geological experts estimate that a 6.9 magnitude earthquake along the Rose Canyon fault would cause significant damage to coastal areas from Coronado to San Onofre. Nearby offshore faults caused the 5.4 magnitude 1986 Oceanside earthquake, killing one resident and injuring at least 29.
Southern California Edison, which operates the San Onofre storage facility, says the spent fuel is safely contained in sealed stainless-steel canisters housed in underground steel-and-concrete structures.
But Day’s concern is less about whether the canisters can withstand an individual earthquake than about where the waste is being stored over the very long term.
“San Onofre is sitting on some fairly young rock. This is not the sort of place you’d leave nuclear waste,” Day said. “You wouldn’t leave nuclear waste in a place like Yucca Mountain, which is on the Walker Lane fault system. What you would choose are geologically stable parts of your nation and the most geologically stable are actually in the northern states, places like Michigan and around the Great Lakes region.”
The Nuclear Regulatory Commission, which licenses and oversees the storage system, requires the facility to be evaluated for hazards like earthquakes and floods. To get approval, Edison had to demonstrate the facility could withstand those threats.
The commission’s standards also require ongoing monitoring as the storage system ages — an important consideration for fuel that could remain at San Onofre for decades or longer while the federal government searches for a permanent disposal site.
The potential risks aren’t limited to environmental hazards. Researchers are also studying whether living near nuclear power plants could be associated with health impacts — although that research does not specifically examine San Onofre’s spent fuel storage.
Alwadi Yazan, a Harvard public health Ph.D researcher, has developed a new model to measure the health impacts of environmental exposure to radiation from nearby power plants.
Yazan’s study analyzed more than 20,000 cancer cases in Massachusetts between 2000 and 2018 and found an association between cancer rates and proximity to nuclear power plants. The study found the strongest association within three miles of nuclear plants, with no statistically significant association beyond 15 miles.
Across multiple studies and an independent comparison study in South Korea, Yazan says, there is a consistent association between close proximity to nuclear power plants and increased cancer rates. Unlike previous research that relied on arbitrary distance cutoffs, Yazan’s team uses a continuous model to better measure the possible connection between exposure and cancer risks.
Yazan emphasized that the research does not establish that living near a nuclear power plant causes cancer. Instead, it identifies a correlation — not causation — that he says warrants further study.
“This finding is not a conclusion,” Yazan said. “It’s the starting point for a line of work, one that narrows the question with each study.”
Searching for a solution
As the federal government looks to expand nuclear power, states are proposing new ways to manage the resulting waste. The proposals are part of a Department of Energy initiative that aims to “reestablish global leadership in nuclear energy” and make America energy independent.
Nuclear Lifecycle Innovation Campuses are voluntary federal-state partnerships that would support the system behind nuclear power, from enriching new fuel to producing power and disposing of spent fuel.
Utah, Tennessee, Oklahoma, Louisiana and Idaho have signed agreements with the Energy Department to pursue the first innovation campuses, according to the agency. Finalists will be chosen later this year.
Each state proposes a way they can contribute to the initiative and the nation’s nuclear power industry. At the symposium, a unique proposal out of Utah drew attention as a possible fix for America’s waste management problem.
Tim Kowalchik, research director for Utah’s Office of Energy Development, said Utah’s proposal — deep borehole storage — could be among the most competitive.
The proposal would use drilling technology developed in the oil and gas industry to place high-level nuclear waste and spent fuel deep underground, potentially as much as three miles below the surface. The waste would be sealed in corrosion-resistant containers before being placed in the boreholes.
Deep borehole disposal is one of several concepts being considered for isolating nuclear waste deep underground. Unlike Yucca Mountain, which would rely on a large mined repository, the approach would use narrow, deep wells to isolate waste from the surface and groundwater.
Utah officials have identified a site in Tooele County, near the Great Salt Lake, as a potential location. They say as much as half of the site could eventually be used for nuclear waste storage.
