ML25212A252
| ML25212A252 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/31/2025 |
| From: | Bird P, Curran D, Swanson J Harmon, Curran, Harmon, Curran, Spielberg & Eisenberg, LLP, San Luis Obispo Mothers for Peace, Univ of California - Los Angeles |
| To: | Annie Caputo, Crowell B, Mike Franovich, Marzano M, Padilla A, David Wright NRC/Chairman, Office of Nuclear Reactor Regulation, NRC/OCM/AXC, NRC/OCM/BRC, NRC/OCM/MJM, US SEN (Senate) |
| SECY RAS | |
| References | |
| RAS 57430, 50-275-LR-2, 50-323-LR-2 | |
| Download: ML25212A252 (0) | |
Text
July 31, 2025 Hon. Alex Padilla United States Senate 255 E. Temple Street Los Angeles, CA 90012 c/o Nate Bentham, nate_bentham@padilla.senate.gov
SUBJECT:
NRC final decisions refuse to grapple with serious seismic risk at Diablo Canyon nuclear plant
Dear Senator Padilla,
Just two days after the 8.8 magnitude earthquake in eastern Russia, we write to inform you of two recent decisions by the U.S. Nuclear Regulatory Commission (NRC) renouncing the NRCs 2023 commitment made to you by then-NRC Chairman Christopher Hanson, to evaluate seismic risk to the Diablo Canyon nuclear plant as part of the license renewal process for the reactors.
First, on July 15, 2025, the NRC issued its final decision in the license renewal proceeding for Diablo Canyon, refusing to honor the NRCs commitment to you on the ground that seismic risks fall outside the scope of license renewal proceedings, a decision irreconcilable with the NRCs commitment to you. See pages 11-12. By that time, of course, President Trump had fired Commissioner Hanson without cause. Therefore, he had no opportunity to participate in the decision.
In an audacious display of circular reasoning, the Commissioners held that Pacific Gas &
Electric (PG&E) was not required to address seismic risks in its license renewal application, and then faulted the petitioners for failing to show a problem with the same application. Id.
Second, on July 23, 2025, the NRC refused to review a decision by NRCs Petition Review Board (PRB) denying our seismic enforcement petition against continued operation of Diablo Canyon. The Commissions refusal to engage the PRB is very troubling because the PRB completely failed to address Dr. Peter Birds serious and thoroughly reasoned and supported concerns1 to the effect that continued operation of Diablo Canyon is unsafe and in violation of NRC regulatory requirements. Instead, the NRC regurgitated a collection of marginally-relevant 1 See Petition submitted by San Luis Obispo Mothers for Peace, Friends of the Earth, and Environmental Working Group (March 4, 2024) (ML24067A066); Petition Supplement (June 7, 2024) (ML24162A079); Petitioners Presentation to the PRB (July 17, 2024) (ML24198A105);
Public Meeting Transcript (July 17, 2024) (ML24218A164); Petition Supplement (October 30, 2024) (ML24305A187); Comments on Proposed Directors Decision (May 15, 2025)
(ML25136A355).
Hon. Alex Padilla July 31, 2025 Page 2 half-truths culled from previous filings by PG&E. See Dr. Birds detailed criticism of the decision is attached.
By themselves, these decisions demonstrate a disturbingly cavalier disregard for your role in providing Congressional oversight of the NRC, including serving the interests of your California constituents. And of course the decisions were made in the much larger and deeply alarming context of the Trump Administrations takeover of the formerly independent NRC by DOGE; the issuance of executive orders to elevate cost considerations over safety; the termination of Commissioner Hanson, a strong safety advocate; and the hollowing-out of NRCs experienced senior management organization, leaving significant management responsibility to acting officials. And the desertions continue. Just yesterday, even the solidly pro-industry Commissioner Annie Caputo announced her early retirement.
In conclusion, we stress that the NRC made an explicit commitment to you and to your California constituents through the words of its chairman in the presence of the other commissioners and much of the senior staff. We trust that you too are offended by the NRCs cavalier welching on that solemn commitment in a manner that would endanger much of California in the event of an earthquake comparable to Fukushima or to the one that just occurred in Russia.
Decline in the quality of NRC regulation seems inevitable in light of recent reckless Trump administration behavior elevating speed over safety. We urge you to insist that the NRC adhere to the commitments that it has made to the state of California and to you.
Sincerely,
/s/Jane Swanson Jane Swanson, Board President San Luis Obispo Mothers for Peace Cc: Hon. Adam Schiff c/o Dahvi Cohen, dahvi.cohen@schiff.senate.gov Hon. Salud Carbajal Brooksley Pruitt brooksley.pruitt@mail.house.gov Diablo Canyon Independent Safety Committee c/o Robert Rathie info@dcisc.org John Laird c/o Kara Woodruff kara.woodruff@sen.ca.gov Members of Independent Peer Review Panel:
California Geological Survey Dawson, Timothy timothy.dawson@conservation.ca.gov Chen, Rui Rui.Chen@conservation.ca.gov Zachariasen, Judith Judith.Zachariasen@conservation.ca.gov Seitz, Gordon Gordon.Seitz@conservation.ca.gov Seismic Safety Commission Wang-Connelly, Jia Jia.Wang-Connelly@CalOES.ca.gov Ortiz, Nate Nate.Ortiz@CalOES.ca.gov California Coastal Commission Street, Joseph Joseph.Street@coastal.ca.gov
Hon. Alex Padilla July 31, 2025 Page 3 California Public Utilities Commission Anderson, Robert "Bob" Lowell bobanderson816@gmail.com Mulligan, Jack M. jack.mulligan@cpuc.ca.gov Carrejo, Antonio Antonio.carrejo@cpuc.ca.gov Zizmor, David David.zizmor@cpuc.ca.gov California Energy Commission Cochran, Justin justin.cochran@energy.ca.gov San Luis Obispo Bruce Gibson bgibson@co.slo.ca.us Crystal Tompkins ctompkins@co.slo.ca.us Blake Fixler bfixler@co.slo.ca.us Department of Water Resources Hou, Delphine Delphine.Hou@water.ca.gov Wood, Colin Colin.Wood@water.ca.gov Hedrick, Robert Robert.Hedrick@water.ca.gov
July 31, 2025 David A. Wright, Chair1 Annie Caputo, Commissioner Bradley R. Crowell, Commissioner Matthew J. Marzano, Commissioner Michael X. Franovich, Deputy Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555-001 By email to Dennis Galvin dennis.galvin@nrc.gov
SUBJECT:
Directors Decision Regarding Seismic Core Damage Frequency For Diablo Canyon Nuclear Power Plant, Units 1 and 2
Dear NRC Commissioners and Mr. Franovich:
We write to protest the gross and alarming inadequacy of Directors Decision DD-25-01 (June 26, 2025) (DD-25-01) to address the serious and thoroughly reasoned and supported concerns regarding seismic risk to the Diablo Canyon nuclear power plant (DCPP) that have been raised by Dr. Peter Bird on behalf of San Luis Obispo Mothers for Peace, Friends of the Earth, and Environmental Working Group. Unfortunately, DD-25-01 is a collection of marginally-relevant half-truths culled from previous filings by Pacific Gas & Electric Co. (PG&E) that completely fail to refute our key concerns. Specifically:
(1) DD-25-01 fails to refute Dr. Birds contention that PG&Es Seismic Source Characterization studies (2015, 2024) were deficient because they never investigated or modeled the mechanism of formation of the Pismo syncline since 5 Ma. Because of this, at least two gently-dipping thrust faults under the Irish Hills are missing from PG&Es fault geometry models, from which all hazard and risk estimates flowed. PG&E also failed to consider that the basement under the Irish Hills is Franciscan Complex, which was assembled by gently-dipping thrust faults, available for reactivation.
(2) DD-25-01 also ignores PG&Es failure to include modern deformation modeling, as routinely contracted by the USGS for regional seismic hazard models. Deformation models would have shown that the ~1.8 mm/year shortening across the Irish Hills indicated by GPS geodesy data must lead to high slip rates on gently dipping thrusts, including at least one below DCPP.
(3) Further, DD-25-01 fails to recognize that the Irish Hills are isostatically supported, as shown by their negative isostatic gravity anomaly. This means that every foot of relative vertical displacement (throw) on thrust faults produces only ~2 inches of surface uplift, 1 To our knowledge, Mr. Wrights appointment as NRC Chairman has been confirmed and is awaiting imminent fulfillment.
NRC Commissioners and Michael X. Franovich July 31, 2025 Page 2 while the footwall of the thrust subsides by ~10 inches. PG&E has underestimated the hazard from every thrust fault by a factor of 6 when they calculated slip rates from surface uplift rates, because they ignored isostasy.
(4) Contrary to the NRCs assertion (DD-25-01 page 14) the vertical offset (throw) of map unit Tmo at the southern coast cannot be explained by Miocene normal faulting. In the specific fault geometry mapped by PG&E, any Miocene normal offset of unit Tmo would lead to a rate of Pliocene-Quaternary thrusting even higher than I have estimated.
(5) As discussed in a recent meeting of the Diablo Canyon Independent Safety Committee (DCISC), Dr. Bird and the Seismic Review Team (SRT) employed by the DCISC to evaluate Dr. Birds claims agree that there is an active thrust fault directly under Diablo Canyon Power Plant. PG&Es claim to have considered such a model (in 2015 and 2024) is seriously misleading in two respects: first, PG&E assigned that model an unrealistic logic-weight of only ~10%, and (b) PG&E assigned an unrealistically low slip-rate and an unrealistically steep dip to minimize the hazard. Further, a member of the SRT confirmed that PG&E has not evaluated the capacity of this thrust fault.
PG&Es unrealistic modeling of this active thrust fault, coupled with its failure to evaluate the capacity of the fault, are highly troubling, given the faults location directly beneath DCPP.
For all of the reasons stated above, the warning signs of an unacceptably high seismic hazard and risk at Diablo Canyon have not been dispelled.
Thank you for your consideration.
Sincerely, Diane Curran Counsel to San Luis Obispo Mothers for Peace Peter Bird Professor Emeritus Department of Earth, Planetary, and Space Sciences University of California Los Angeles Los Angeles, CA 90095-1567 Technical advisor to San Luis Obispo Mothers for Peace CC:
Hon. Alex Padilla Hon. Adam Schiff
NRC Commissioners and Michael X. Franovich July 31, 2025 Page 3 Hon. Salud Carbajal Diablo Canyon Independent Safety Committee c/o Robert Rathie info@dcisc.org John Laird c/o Kara Woodruff kara.woodruff@sen.ca.gov Members of Independent Peer Review Panel:
California Geological Survey Dawson, Timothy timothy.dawson@conservation.ca.gov Chen, Rui Rui.Chen@conservation.ca.gov Zachariasen, Judith Judith.Zachariasen@conservation.ca.gov Seitz, Gordon Gordon.Seitz@conservation.ca.gov Seismic Safety Commission Wang-Connelly, Jia Jia.Wang-Connelly@CalOES.ca.gov Ortiz, Nate Nate.Ortiz@CalOES.ca.gov California Coastal Commission Street, Joseph Joseph.Street@coastal.ca.gov California Public Utilities Commission Anderson, Robert "Bob" Lowell bobanderson816@gmail.com Mulligan, Jack M. jack.mulligan@cpuc.ca.gov Carrejo, Antonio Antonio.carrejo@cpuc.ca.gov Zizmor, David David.zizmor@cpuc.ca.gov California Energy Commission Cochran, Justin justin.cochran@energy.ca.gov San Luis Obispo Bruce Gibson bgibson@co.slo.ca.us Crystal Tompkins ctompkins@co.slo.ca.us Blake Fixler bfixler@co.slo.ca.us Department of Water Resources Hou, Delphine Delphine.Hou@water.ca.gov Wood, Colin Colin.Wood@water.ca.gov Hedrick, Robert Robert.Hedrick@water.ca.gov
CERTIFICATE OF SERVICE I certify that on July 31, 2025, I posted a on the NRCs Electronic Information Exchange the attached letter from Jane Swanson to Senator Alex Padilla, with an attached letter from Diane Curran and Peter Bird to the Commissioners and Dennis Galvin of the NRCs Petition Review Board.
Signed electronically by Jill ZamEk, San Luis Obispo Mothers for Peace