Nuclear Safety Issues at San Onofre

San Onofre

The San Onofre nuclear power plant near San Clemente closed permanently in June 2013, a year and a half after defective steam generators costing $680 million and leaked radiation.

San Onofre is one of dozens of U.S. reactors that faced scrutiny after Japan’s nuclear crisis. It is located right on the coast, and in the heart of America’s earthquake country.

It also is right next door to Camp Pendleton, a Marine Corps base where 38,000 military families live, and another 32,000 people work each day, all of whom that would be in immediate danger if there’s ever a meltdown.

When it was operating at full capacity, San Onofre made enough electricity to run more than 1.4 million homes in Southern California.

Are San Onofre nuclear waste canisters cracking?

Intergrain Stress Corrosion CrackingNo one knows because there is no technology to inspect or repair cracks in these thin stainless steel canisters. Southern California Edison has no adequate plan to replace cracked canisters and their monitoring system only alerts us after the canisters leak radiation.  Yet they plan to buy more of these inferior canisters.  Conditions for cracking were found on a Diablo Canyon canister in service for only two years. Diablo Canyon is located in San Luis Obispo County in a similar environment as San Onofre. See details below.



Used Nuclear Fuel U.S. 2013 NEISan Onofre’s nuclear reactors are shut down. However, thousands of metric tons of radioactive nuclear waste will remain in California for decades.  San Onofre’s spent fuel contains 89 times the amount of radiation (Cesium-137) released from Chernobyl.  The waste is not safely stored, putting us at risk for a major nuclear disaster. Please read these facts and share the information. The facts are from the Nuclear Regulatory Commission (NRC) and other government and scientific sources.  More…

Stress Corrosion Cracking NRC Slide2 07-14-2014The (1/2 – 5/8 inch) thin stainless steel canisters storing radioactive nuclear waste at U.S. nuclear power plants may fail within 30 years. There is no current remediation plan.  This waste may need to be stored at nuclear plants or interim storage sites for over 100 years. Once canisters are loaded with spent fuel, they are no longer inspected for aging issues or monitored for helium leaks. These are just some of the problems with U.S. dry storage cask/canister systems. More…


Chart SONGS Chernobyl Other Alvarez, Figure 4

San Onofre (SONGS): 89 times more radiation than Chernobyl

HIGH BURNUP FUEL: San Onofre and other U.S. reactors switched to the more dangerous high burnup nuclear fuel over a decade ago. High burnup fuel is low enriched uranium that has burned longer in the reactor than lower burnup fuel.

High burnup fuel is over twice as radioactive,  hotter than lower burnup fuel, and unpredictable and unstable in storage and transport. The protective fuel cladding is more likely to become brittle and shatter, risking release of radiation.


Higher burnup = higher cladding failureThe majority of spent nuclear fuel at San Onofre falls into the danger zone as shown by the yellow in this Waste at SONGS chart.

Burnup levels as low as 30 GWd/MTU show indications of damaging the protective Zirconium cladding.

Other U.S. nuclear plants have spent fuel that falls within the danger zone, including Diablo Canyon in San Luis Obispo County.  More…



Years to Cool Chart

High burnup nuclear fuel: up to 20+ years to cool

There is no approved method to safely store high burnup fuel in dry casks for more than 20 years. And there is no approved method to safely transport high burnup fuel wasteThis fuel is so hot, it must cool in the spent fuel pools years longer than lower burnup fuel.  Edison plans to store high burnup fuel in a new model dry cask that would make it even more dangerous. More….


Safety Allegations Charts

Worst safety complaint record in the nation!

The San Onofre Nuclear Power Plant has the worst safety complaint record of all U.S. nuclear reactors according to Nuclear Regulatory Commission (NRC) safety allegation data. See charts for details. Employees are retaliated against for reporting safety problems. See Safety Allegations Section for details on this and other safety complaints by employees and others. More…

Steam Generator Tubes Plugged Chart

Worst steam generators in the nation!

Southern California Edison wanted to restart the Unit 2 nuclear reactor without fixing the defective steam generators. Both reactors have been shut since 1/31/2012, when Unit 3 leaked radiation into the environment. All four poorly designed replacement steam generators show decades of tube wear after less than two years of installation – the worst in the nation.  


San Onofre Lemons

The NRC concluded Southern California Edison was at fault.  “…a significant design deficiency in replacement steam generators, resulting in rapid tube wear of a type never before seen in recirculating steam generators.”   In the NRC’s 12/23/2013 Notice of Violation, they stated: “…design control measures were not established to provide for verifying or checking the adequacy of certain designs.”


Typical Combustion Engineering Steam GeneratorEdison now admits the steam generators are lemons.  However, they were willing to restart Unit 2 without repairing them.  Edison and Mitsubishi Heavy Industries (MHI) redesigned the steam generator tube anti-vibration system in order to increase profits. They removed the central stay cylinder in order to add about 400 extra tubes to each generator. Read Arnie Gundersen’s  Fairewind Associates Report San Onofre’s steam generators: significantly worse than all others nationwide and 10/2/2014 NRC Office of Inspector General report where former NRC directors say the steam generators should never have been licensedMore…


Excess Power without Nuclear ChartCalifornia has excess power without California’s unreliable nuclear power plants, even during peak summer months, according to California government documents. There should be no power problems with San Onofre shut down, even during the summer. And the California ISO’s electricity grid  Transmission Plan says there will be no grid stability concerns with San Onofre shut down. More…


OTC NPP Highest Damage ChartThe San Onofre and Diablo Canyon nuclear plants kill millions of fish and other marine life every year, due to their once-through cooling (OTC) systems. The Federal Clean Water Act §316(b) regulations declared OTC illegal. However, California is allowing both plants to continue OTC for years.  More…. .



San Onofre Nuclear Power Plant

San Onofre Nuclear Power Plant

The NRC lowers safety standards to keep old plants running. More…

“If the NRC does not do its job, the American people will demand the ultimate protection – the shutdown of old nuclear power plants…”, says Senator Barbara Boxer to NRC Commissioners

Four NRC Commissioners undermine safety. Rep. Darrell Issa appears to support them.


Earthquake MapSan Onofre is designed for a 7.0 earthquake, but sits next to a fault with an  8.0+ earthquake probability — 10 times larger, 32 times stronger, and long overdue. Ratepayers funding $64 million in new seismic studies, even though the USGS states no scientist can predict the size of any earthquake. Recent quakes > 7.0:


Nuclear meltdown at San Onofre would poison the nation’s food supply, create permanent “dead zones” and create financial ruin around the nation. If you live within 50 miles of San Onofre, you are at even higher risk of losing everything you care about here.  Five counties are within the 50 mile zone: Los Angeles, Orange, Riverside, San Bernardino and San Diego.



Children tested for radiation near Fukushima Daiichi nuclear plant in Japan (Kim Kyung-Hoon/Reuters)

There is no safe level of radiation, according to the National Academy of Sciences. Children, unborn babies and women are more susceptible to the effects of radiation. Ingesting radiation is extremely dangerous. More…

Tuna near San Diego was found to contain radiation from Japan. Kelp along the Orange County coast also  contained Fukushima radiationRadiation monitoring is inadequate. Government resources and priorities for radiation monitoring are too low to protect us.  More…

Fukushima USA Cesium-137 Fallout Map 2011 NADP

NADP sites where USGS measured Fukushima Cesium-137 in Mar-Apr 2011 precipitation samples. Dot size = relative amounts (0.8 – 240 Bq/m2).



The Fukushima Daiichi nuclear disaster continues and radiation from Fukushima has traveled to the U.S., yet limited radiation data is available to the public. See NRC Fukushima Lesson’s Learned for status of what the NRC and U.S. reactors are doing [or not doing] to avoid similar problems.



Without public awareness and involvement this nuclear energy experiment will continue. Our government will only stop approving high burnup nuclear fuel if our elected officials know they will not be reelected if they support this nuclear energy experiment.  We need better nuclear waste storage containers that are designed for safety over cost. We don’t need to live with these serious risks for energy we don’t need.  See Energy Options.

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About San Onofre Safety (SOS)

This website is a self-funded public resource for creditable information about San Onofre Nuclear Power Plant safety issues, cost issues and related information. Much of the information is relevant to other nuclear power plants and their nuclear waste. The information was extensively research and fact checked by local citizens and organizations concerned about the risks from San Onofre and other nuclear power plants. By improving  public awareness, our goal is to reduce the likelihood of a nuclear disaster in California and elsewhere. The San Onofre nuclear reactors and highly toxic radioactive waste storage facilities are located just south of San Clemente, California. Diablo Canyon nuclear power plant is located in San Luis Obispo county. California’s Humboldt and Rancho Seco nuclear reactors are shut down, but their highly toxic radioactive waste is stored on-site — indefinitely.


Southern California Edison decided to decommission the San Onofre nuclear reactors on June 7th, 2013, after the NRC’s Atomic Safety and Licensing Board said restarting the Unit 2 reactor would be a nuclear experiment.  

Thanks to Kendra UlrichShaun BernieDamon Moglen and S. David Freeman with Friends of the EarthArnie and Maggie Gundersen, Fairewinds AssociatesDan Hirsch, Committee to Bridge the GapSenator Barbara Boxer; and California concerned citizens, elected officials and others who vigilantly fought Southern California Edison and the Nuclear Regulatory Commission to allow the truth to prevail.  And a special thanks to the concerned citizens who contributed millions of dollars to help keep Southern California safe from a nuclear disaster.





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