New report reveals scale of Edison steam generator failures at San Onofre nuclear plant

New report reveals scale of Edison steam generator failures at San Onofre nuclear plant

Engineer warns that tube plugging and low power operation are risky “non-solutions”

WASHINGTON, D.C. – Southern California Edison avoided federal regulatory guidelines when replacing defective steam generators at the San Onofre nuclear power plant — a costly mistake that can’t be fixed by plugging the tubes that carry radioactive steam or by operating the plant at reduced power, according to a new report released today by Friends of the Earth.

The content of the report by nuclear engineer Arnie Gundersen details the significant design changes that should have triggered a license review which would have uncovered problems that subsequently led to serious damage and the release of radiation from the defective equipment at San Onofre in January.

Gundersen also criticizes Edison’s plans to rapidly restart the damaged reactors at lower power after having done minimal plugging of damaged tubes carrying radioactive water. He warns that these are “non-solutions” that could lead to even more significant equipment failure and releases of radiation.  Edison is expected to propose running the reactors at between 50 and 80 percent power. The report challenges the safety and effectiveness of such an approach, concluding:

  • Reducing power does not provide a remedy for the underlying structural problems that are creating the vibration that has damaged and will continue to damage the tubes deep inside the San Onofre steam generators;
  • Reducing power will not change the pressure inside or outside the tubes – previously damaged tubes will continue to vibrate damaging surrounding tubes and tube supports and worsening the existing damage;
  • Lower power might create a resonate frequency at which vibration might increase without notice causing further damage;
  • Historical evidence at other reactors has shown that operating at lower power has not been an effective solution.

Gundersen concludes that plugging the tubes and restarting the reactor could lead to catastrophe: “If a steam-line accident were to occur, vibrationally induced tube damage at San Onofre could cause an inordinate amount of radioactivity to be released outside of the containment system, compromising public health and safety in one of the most heavily populated areas in the United States.”

“Edison should never have been allowed to install these fundamentally defective steam generators,” said Damon Moglen, climate and energy campaign director at Friends of the Earth. “Now Edison is planning to avoid dealing with the underlying problems and instead restart at lower power. Their claims of nuclear safety first ring completely hollow and must be stopped.”

Read the report here:


Summary of the report with video demonstrating the problems:


Bill Walker, 510-759-9911, [email protected]
Damon Moglen,  202-222-0708, [email protected]

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