San Onofre Nuclear Waste Remains Secure During Flooding
Engineered seawalls protect millions of pounds of spent fuel as the region navigates a coastal flood advisory.
Updated on Oct. 30, 2026 in Nuclear
Live Poll
Do you trust that nuclear waste stored near your coast is safe from extreme weather events?
Southern California Edison is monitoring the San Onofre Nuclear Generating Station during a Coastal Flood Advisory for San Diego and Orange counties. The decommissioned site currently stores 3.55 million pounds of nuclear waste within reinforced canisters designed to withstand extreme flooding and high water velocity.
Why it matters
The lack of a permanent federal repository for spent fuel leaves millions of pounds of radioactive material in temporary storage near rising seas. Facility managers must continue to rely on localized engineering defenses to manage these sites indefinitely.
The storage system features 73 vertical and 50 horizontal canisters shielded by a 28-foot-high seawall. Engineering standards specify the canisters can survive total submergence in 50 feet of water and water velocity reaching 15 feet per second.
The players
Southern California Edison
A major utility provider operating the decommissioned San Onofre nuclear site and managing its ongoing waste storage and dismantling.
National Weather Service
The federal agency responsible for issuing meteorological warnings, including the current coastal flooding advisory.
The details
Spent fuel is housed in vertical cavities and horizontal stacked systems located 100 feet from the Pacific Ocean. The storage units are encased in materials engineered to maintain structural integrity under hydrostatic pressure and high-velocity water flow. Southern California Edison reviews annual independent sea level rise assessments to ensure current environmental conditions remain within the facility’s original design analysis parameters.
Timeline
2010: Federal funding for the Yucca Mountain permanent waste repository was terminated.
2012: A steam generator leak occurred, ultimately leading to the closure of the plant.
October 30, 2026: The current Coastal Flood Advisory for the region expires at noon.
Early 2027: Exterior demolition of the remaining containment domes is scheduled to begin.
The Tech Race
The situation at San Onofre highlights the ongoing consequences of the 2010 cancellation of federal funding for the Yucca Mountain repository, which forces utilities to maintain waste in temporary, site-specific locations. With no federal solution for the 95,000 metric tons of spent fuel stored across 35 states, operators must focus on site-specific physical hardening rather than centralized disposal.
Residents in Orange and San Diego counties should follow guidance from local emergency services during the active flood advisory. The site's safety measures remain static, and officials continue to process the removal of non-radioactive structural materials, with over 750 million pounds of waste already shipped offsite via rail.
The takeaway
The lack of a permanent federal repository for spent nuclear fuel necessitates indefinite reliance on localized defensive structures for coastal power plants. Observers should track the 2027 start of exterior containment dome demolition as a marker of progress in the long-term decommissioning project.
What happens next
The demolition of the remaining containment domes is slated to commence in early 2027, representing the next phase in the site's decommissioning process.
Further reading
For more background on nuclear infrastructure and waste management policies, see the Nuclear section.
Live Poll
Do you trust that nuclear waste stored near your coast is safe from extreme weather events?
