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Nuclear Power

The Nuclear Regulatory Commission (NRC) has authority over the safety and operational aspects of nuclear power plants in the U.S.


The CPUC has authority over financial matters affecting the nuclear plants owned by the utilities it regulates:

  • PG&E’s Diablo Canyon Power Plant (DCPP): Units 1 and 2  - 1,100 MW each.
  • PG&E’s Humboldt Bay Power Plant: Unit 3 currently being decommissioned.
  • San Onofre Nuclear Generating Station (SONGS): Operated by Southern California Edison (SCE), which owns 78 percent; SDG&E, which owns 20 percent; and Southern California municipal utilities, which own 2 percent; Units 2 and 3 – 1,170 MW each; Unit 1, 2, and 3 are being decommissioned.
  • Palo Verde Nuclear Generating Station (PVNGS) located in Arizona: Approximately 20 percent owned by SCE; operated by Arizona Public Service; Units 1, 2, and 3 -1,300 MW each.

Both DCPP and SONGS provide needed resources to the system. SONGS is located in the L.A. Basin Local Area.  The L.A. Basin local area has approximately 12,300 MW of generation and requires 10,600 MW to maintain reliability.  SONGS, at 2,340 MW, is critically located in the southern part of the local area and aids system stability in addition to megawatts.


Please see our April 14, 2011, Senate Hearing presentation on Nuclear Power Plant Issues at the CPUC.


Cost Recovery for Nuclear Generation at the CPUC

  • Non-fuel operating costs are typically recovered in a utility’s General Rate Case (GRC).
  • Major capital additions, such as steam generator replacements for SONGS and DCPP, were addressed in separate proceedings.
  • Fuel costs recovered through Energy Resource Recovery Account proceedings.
  • Decommissioning costs recovered in the Nuclear Decommissioning Cost Triennial Proceeding.
  • Other proceedings are addressing cost recovery for seismic studies and relicensing DCPP and SONGS.

Nuclear Decommissioning Costs & Trusts

  • D.87-05-062 established nuclear decommissioning trusts for funding future decommissioning of the utilities’ nuclear units.
    • Each nuclear plant has decommissioning trusts and a committee that oversees the trust fund; the CPUC approves non-utility trust committee members.
  • D.10-07-047 in Phase 1 of the most recent Nuclear Decommissioning Cost Triennial Proceeding (A.09-04-007, A.09-04-009) adopted:
    • $207 million for SONGS 1 decommissioning work done from 2005 – 2008, $184 million for remaining decommissioning work at SONGS 1, and $3.7 billion estimate for decommissioning SONGS 2 and 3;
    • $709 million estimate for SCE’s share of PVNGS decommissioning;
    • Contributions to SONGS 2 and 3 trusts of $23 million for SCE and $8 million for SDG&E;
    • Decommissioning cost estimates of $1.8 billion for DCPP and $500 million for Humboldt 3; and $14 million contribution to Humboldt 3 trust, and $9 million contribution to DCPP trust; and,
    • Established an independent panel to assess parameters for future decommissioning cost studies.

Phase 2 of the NDCTP A.09-04-007, et al, is addressing nuclear trust management, selection, and investments.


Seismic Studies at DCPP


CPUC (D.10-08-003) authorized PG&E’s request for $16.7 million to perform enhanced 2-D and 3-D seismic studies in the vicinity of DCPP.

  • PG&E’s request was in response to recommendations made by the California Energy Commission in its report pursuant to AB 1632 (2006), to assess the Shoreline Fault.
  •  PG&E’s preliminary assessment is that the Shoreline Fault would not exceed an earthquake of magnitude 6.5.  DCPP is currently designed to withstand a 7.5 magnitude earthquake based on the Hosgri Fault.   The 2011 northeastern Japan earthquake was magnitude 9.0.

In the same Decision the CPUC created an Independent Peer Review Panel (IPRP).

  • Under the auspices of the CPUC, the IPRP includes participation of other state agencies such as the California Energy Commission, California Seismic Safety Commission, California Coastal Commission, and the California Geological Survey, to review PG&E’s plans and analyses of its enhanced seismic studies.

April 22, 2015:  PG&E response to IPRP Reports Nos. 7, 8, and 9

March 6, 2015:  IPRP Report No.9 on DCPP Seismic Studies

February 2, 2015:  IPRP response Letter to CPUC and CEC on A4NR

January 14, 2015:  A4NR letter to CPUC and CEC

December 17, 2014: IPRP Report No.8 on DCPP Seismic Studies

November 21, 2014: IPRP Report No.7 on DCPP Seismic Studies 

July 17, 2013:  IPRP Report No.6 on DCPP Seismic Studies

March 25, 2013:  IPRP Report No.5 on DCPP Seismic Studies

February 25, 2013:  2013 IPRP meeting with PG&E on DCPP Seismic Studies 

November 28 2012:  IPRP poster at NRC workshop for DCPP Seismic Studies

October 25, 2012: IPRP Letter to CA Coastal Commission

October 18, 2012:  PG&E Letter DCL-2012-654, Seismic Imaging Project for DCPP

September 25, 2012:  IPRP Report No.4 on DCPP Seismic Studies

April 6, 2012:  IPRP Report No.3 on DCPP Seismic Studies

September 11, 2011:  IPRP Report No.2 on DCPP Seismic Studies

September 30, 2010:  IPRP Report No. 1 on DCPP Seismic Studies 


Relicensing DCPP Request to NRC


In November 2009, PG&E filed at the NRC a request for 20-year license extensions for DCPP Units 1 and 2.  If approved by the NRC, the licenses for operating these units would be extended until 2044 and 2045, respectively.


In January 2010, PG&E filed A.10-01-022 at the CPUC requesting authority to recover costs estimated at $85 million to obtain the State and Federal approvals related to license renewal at DCPP.

  • PG&E, TURN, and DRA filed a settlement which would allow PG&E to recover up to $80 million for license renewal activities, and to seek separate recovery of additional amounts incurred, subject to reasonableness review, in its next GRC.
  • A hearing scheduled to address whether the settlement should be adopted and whether funding should be authorized before seismic studies at DCPP are completed, has been removed from the CPUC calendar to be reset on motion of the parties.

CPUC Investigation Into SONGS Outages And Closure


San Onofre Nuclear Generating Station Units 2 and 3 were temporarily shut down in January 2012, and were permanently closed on June 7, 2013. The CPUC has an open investigation into the unanticipated outage, which includes evaluating whether to remove all costs related to San Onofre from the rates of SCE and SDG&E going forward, and whether to refund San Onofre-related costs already collected in rates back to January 1, 2012.


Nov. 19, 2013: CPUC Issues First in Series of Proposed Decisions to Protect Consumers From Overpaying for San Onofre-Related Costs: CPUC Information Alert


View proceeding documents


SONGS Seismic Studies and Relicensing


August 5, 2013:  SCE's Response Comment to Commissioner Florio's Letter

July 17, 2013:  Independent Peer Review Group (IPRG) Report No.2 for SONGS Studies

July 17, 2013:  Letter from Commissioner Florio on Seismic Studies

June 7, 2013:  CPUC President Comments on Closure of SONGS: CPUC Press Release

March 12, 2013:  March 2013 SONGS Site Characterization Report

February 25, 2013:  SCE presentation at IPRG meeting for SONGS Seismic Studies.

January 15, 2013:  Paleoseismic Trenching Report for SONGS Seismic Studies.

October 16, 2012:  Independent Peer Review Group (IPRG) Report No.1 for SONGS Studies

September 4, 2012:  SONGS Seismic Survery Information from SCE

August 10, 2012:  Additional SONGS Seismic Study Plans

July 18, 2012:  Invitation letter to Orange County to participate in SONGS IPRG

July 9, 2012: SCE submits its plan for SONGS Seismic Research Projects 

May 10, 2012: CPUC Approves Seismic Projects and Analyses for San Onofre


In its Test Year 2012 GRC (A.10-11-015) SCE requested:

  • $29 million for seismic studies at SONGS, of which $21 million is for enhanced 2-D and 3-D seismic studies similar to PG&E’s efforts at DCPP.
  • Approximately $7 million for efforts to continue a feasibility study related to a 20-year license extensions for SONGS Units 2 and 3.

SCE was directed to seek recovery of the costs identified above through separate applications.


SCE is expected to file a request at the NRC in 2013 for 20-year license extensions at SONGS.  Licenses to operate SONGS Units 2 and 3 would be extended until 2042 if approved by the NRC.


Diablo Canyon Independent Safety Committee


The CPUC created the Diablo Canyon Independent Safety Committee in D.88-12-083 when resolving ratemaking issues for DCPP -  a restated charter for the committee was approved in D.07-01-028.

  • The three member Safety Committee assesses safety of DCPP operations and makes recommendations for the plant’s safe operation;
  • The Safety Committee has no responsibility or authority for plant operations, and does not direct PG&E personnel;
  • The Safety Committee conforms to all applicable federal laws, regulations, and NRC policies;
  • The CPUC approves candidates for appointment to the Safety Committee; the Governor, Attorney General, and Chair of the California Energy Commission each appoint one committee member.

The NRC is responsible for assuring the safety and security of all U.S. nuclear power plants including DCPP.  The Safety Committee reviews NRC reports, monitors NRC inspections, and periodically meets with NRC inspectors at DCPP.


Cooling Systems and State Water Board Policy


DCPP and SONGS use once-through-cooling systems that the State Water Resources Control Board has stated do not meet Federal law requiring best available technology.


The Water Board has ordered PG&E and SCE to conduct special studies to investigate alternatives. Studies will consider factors such as engineering, space, and permitting constraints, cost and public safety.


Contracts for Uranium Enrichment Services Require CPUC Approval


The CPUC considers utilities’ contracts for uranium enrichment services.  Examples include:

  • PG&E’s contract with AREVA, LLC., a U.S. company.  Uranium enrichment services for delivery to DCPP from 2015 through 2024.  Contract approved by CPUC Resolution E-4322, May 6, 2010;
  • PG&E’s contract with URENCO Ltd., an international company.  For enriched uranium delivery to DCPP from 2014 through 2023.  Draft Resolution E-4398 expected to be on CPUC April 14, 2011 agenda;
  • Review of AREVA and URENCO contracts done in accordance with PG&E’s conformed 2006 Long-Term Procurement Plan approved by Resolution E-4177, June 2008.

Geophysical Characteristics of Fukushima, Japan March 2011 Event


The major damage to the nuclear power plants in Japan was caused by the tsunami following the 9.0 earthquake, which flooded the backup generators for the pumps that supply cooling water to the reactors and cooling ponds for spent fuel.


The March 2011 tsunami in Japan flooded the Fukushima nuclear plant with sea water at about 30 feet above sea level.


DCPP is about 40 feet above sea level, and its emergency diesel generators are about 85 feet above sea level. This plant was designed for a 7.5 earthquake and a 25 foot tsunami wave.


The SONGS units are a few feet above sea level, and the emergency diesel generators are approximately 30 feet above sea level. This plant was designed for a 7.0 earthquake and a 25 foot tsunami wave.


The December 2004 Indian Ocean tsunami raised water levels by about 100 feet in Indonesia and 40 feet in Thailand.


PG&E’s seismic studies at DCPP include a tsunami analysis based on the 1964 Alaska tsunami resulting from a 9.2 earthquake.


Last Modified: 4/27/2015

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