San Onofre is twisting in the breeze of the new Fairewinds safety report released by activist group Friends of the Earth.
The study raises serious doubts about safety at the Southern California nuclear facility, and says running at reduced power will not solve the tubing trouble that has plagued the plant.
Southern California Edison recently disclosed a tentative plan to run the twin reactors at an unspecified lower power, at least for several months.
Engineers believed reduced power would ease the vibration causing the unusual deterioration of tubes inside the steam generators.
The Fairewinds report, however, says running at reduced power may actually make the damage worse and increase the possibility of cascading safety failures.
The report also expands a previous allegation that Edison misled federal regulators about modifications to the generators. The Nuclear Regulatory Commission (NRC) disputes that claim.
Federal approval is required before Edison will be permitted to power up the plant. In an effort to quiet murmurs, NRC Chairman Gregory Jaczko released a statement earlier this month reiterating that there is no date for a restart.
Following the release of the Fairewinds report, California Sen. Barbara Boxer asked Jaczko for documentation on design changes to the generators, and how the federal agency reviewed them.
The twin reactors at San Onofre have been shut down for more than three months while investigators look into the damage that first came to widespread attention in January when the plant suffered a radioactive gas leak.
Lisa Brenner can be reached via Twitter @lisa_brenner
Correction: The name of Fairewinds was initially misspelled in one instance in this article.