CONTACT: Gary Headrick, San Clemente Green – 949 412 3366; Gene Stone, ROSE, San Clemente – 949 233 7724
Decades-Long Seismic Risk at San Onofre Exposes Failures of Edison & NRC –Environmental Groups Demand Answers
WASHINGTON, May 30 – For nearly three decades, more than 8 million people within 50 miles of the San Onofre nuclear plant have been living with a previously unknown and significant threat to the safety of their communities due to flawed safety equipment and lax oversight. The U.S. Nuclear Regulatory Commission revealed yesterday that emergency diesel generators, required to power the San Onofre nuclear plant in case electrical power is lost, risked being shut down following an earthquake – a problem only discovered two months ago.Local environmental organizations in Southern California have today sent a letter to the NRC demanding answers from both the commission and the nuclear plant operator, Southern California Edison. The letter was signed by Residents Organized for a Safe Environment, San Clemente Green and San Onofre Safety.org.
Southern Californians were stunned to learn that the NRC failed for three decades to examine the impact of an earthquake on the high frequency sensors in the reactors’ emergency backup generators. Edison informed the NRC on May 14 of the discovery that the possibility that a seismic event may cause sensors to shutdown the emergency diesel generators, and that this had not been considered during license assessments for the plant. The Edison document is available here.
Upon discovering the issue, the sensors were immediately turned off, indicating significant concerns regarding the threat these sensors posed to the safety of the reactors. This flaw could have triggered the shutdown of the backup generators following an earthquake. Coupled with an extended loss of offsite power, a valid concern in the earthquake-prone region, failure of the backup generators would cut off essential cooling to both the reactor cores and the spent fuel pools.
The failure of the emergency diesel generators at the Fukushima, Japan, nuclear plant in March 2011 led within a few hours to the start of the meltdown of the nuclear fuel in reactor core in unit 1.
“The failure of the NRC to examine earthquake impacts on critical safety equipment at San Onofre for three decades – a nuclear plant located next to major seismic fault lines – is completely unacceptable,” said Gary Headrick of San Clemente Green, “Community members deserve an explanation from the NRC for this safety failure.”
The San Onofre nuclear plant has been shut down since January following a steam generator tube rupture in Unit 3, which released radioactive steam, and the discovery of excessive wear in the tubes of both units. The steam generators in both operating units had been replaced less than two years ago.
Three technical studies commissioned by Friends of the Earth have detailed the major design changes that have led to the severe damage to the steam generators. <link to reports>. The NRC and Edison are due to report on the failures at San Onofre in the coming weeks.
The misleading information provided Edison regarding the steam generator replacements has raised significant concerns regarding the transparency and safety culture of the operators of San Onofre. The admission that essential emergency diesel generators at San Onofre could be switched off exactly when they are required following an earthquake further highlights the risks of continued operation of the crippled reactors.