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Diablo Canyon Relicensing – Halt for Earthquake Studies – Letter, Targets, Background


Diablo Canyon nuclear power plant is perched on the edge of the Pacific Ocean surrounded by numerous unstudied earthquake faults.  The most recent USGS analysis of the Shoreline fault (discovered in 2008) shows that its length and depth, whether it runs under the plant or connects with the off-shore Hosgri fault, and whether a quake on one fault could trigger the other, producing larger magnitude earthquakes are all unknown.

State Senator Sam Blakeslee, US Representative Lois Capps and the San Luis Obispo County Board of Supervisors (unanimously) have called for a halt to PG&E’s relicensing process until state-of-the-art seismic analyses of the nearby fault zone are completed and independently reviewed.  The state Public Utilities Commission requires this analysis as a condition of relicensing, and the Energy Commission recommends its completion prior to PG&E submitting a relicensing application to the NRC.

Although their current licenses won’t expire until 2024 and 2025, and seismic studies are projected to take only three to four years, PG&E refuses to halt relicensing until they are completed and reviewed.  Despite PG&E’s April 10 request for the NRC to hold final licensing until after completion of those studies, the Nuclear “Regulatory” Commission told the state Senate Energy Committee on April 14  that it will not do so.  PG&E has fought the utilities and energy commissions’ requirement and recommendations for years.

Therefore, this campaign has been initiated to urge Governor Jerry Brown and Senators Barbara Boxer and Dianne Feinstein to adopt and advocate the same position as the SLO County Board of Supervisors, Senator Blakeslee and Representative Capps, and pressure the NRC to stop its Diablo Canyon relicensing process and the PUC to stop its proceedings on permitting PG&E to use rate payer money to fund relicensing.

Please take a few minutes to sign this letter to Brown, Boxer and Feinstein and phone each of them.


Brown – Ph: (916) 445-2841 / Email

Boxer – Ph: (916) 448-2787 / Email

Feinstein – Ph: (415) 393-0707 / Email

Letter to:

Governor Brown,

Senator Boxer,

Senator Feinstein,

re:  Diablo Canyon Relicensing – Halt for Earthquake Studies

The SLO County Board of Supervisors on April 12 unanimously called for a stay of Diablo Canyon relicensing until state-of-the-art seismic studies of nearby faults are completed and independently reviewed.  State Senator Sam Blakeslee (R, Dist. 15) and US Representative Lois Capps (D, Dist. 23) have also made that same call.

Despite that, PG&E refuses to halt its relicensing and funding applications with either the NRC or PUC to conduct those earthquake studies.  Additionally, the NRC has turned down PG&E’s request to hold final license approval until after completion of those studies.  Diablo Canyon reactor licenses won’t begin to expire for 13 years.  These seismic analyses will only take three to four years.

The USGS has found that unknowns regarding this seismic zone include:  the length and depth of the Shoreline fault, whether it runs under the plant or connects with the Hosgri fault, and the potential magnitude of forces unleashed in the event earthquakes are triggered on both faults simultaneously.  PG&E claims that company seismologists assess the magnitude potential of the Hosgri fault is 6.5.  The USGS seismologists set it at 7.3.

The PUC requires this analysis during relicensing, and the Energy Commission recommends its completion prior to PG&E’s submitting a relicensing application to the NRC.  PG&E has fought against that requirement and recommendation for years.

Please use all your available influence to pressure the NRC and PUC to suspend PG&E’s Diablo Canyon relicensing and funding applications until advanced seismic analyses, including 3-D mapping, are completed and independently reviewed.  Please stand with the SLO County Board of Supervisors, Senator Blakeslee and Representative Capps.  It is unacceptable to proceed when we know available information about the plant’s seismic environment and its ability to withstand the potential forces unleashed is pending.  We need you to advocate on behalf of the residents of California, and all those living downwind of Diablo Canyon, who will be affected if negligence of accurate information is allowed to influence the decision-making process.

Thank you,


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David Broadwater

David Broadwater

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