San Onofre 3
DecommissionedSouthern California Edison·San Clemente, CA·PWR·1,080 MWe
?
Current reactor power level from the most recent NRC daily report.
Shut Down
?
Days of continuous operation since the last outage ended. Ranked against all operating units.
4,838
Current Run
days
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Longest recorded period of continuous operation between outages.
4,838
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (532 days for this 24-month cycle unit) with no trips to 0% power.
2
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power). Ranked against all NRC-tracked units.
74.8%
Capacity Factor
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Total NRC-reported scram events (emergency reactor shutdowns). Ranked fleet-wide — fewer scrams = better rank.
2
Scrams
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Years since commercial operation began.
27.8
Operating Age
years
Excellence Score, Records & Plant Facts
Breaker-to-Breaker Runs 2 runs
Breaker-to-breaker runs measure continuous operation between refueling outages using a cycle-adjusted threshold (90% of cycle length minus RFO duration). An active streak means the unit has been running continuously since the last refueling with no trips to 0% power.
San Onofre 3 has logged 2 breaker-to-breaker runs, continuous stretches from one refueling to the next with no trip to zero power. Its longest ran 661 days, and its runs average 629 days.
661
Best Run (days)
3R15 (2008-12-18) → 3R16 (2010-10-10)
629
Avg Run (days)
All Runs
| 2008-12-18 | 2010-10-10 | 661 days | 3R15 → 3R16 |
| 1999-05-17 | 2001-01-03 | 597 days | ? → 3R13 |
About This Site
Written by NukeWorker from public records: facts that do not change. Operator, status and capacity come from the live data elsewhere on this page. Sources: Wikipedia: San Onofre Nuclear Generating Station.
San Onofre Nuclear Generating Station stands on the Pacific coast in San Diego County, California, just south of San Clemente, on land within Marine Corps Base Camp Pendleton.
Read more
Unit 1, a Westinghouse pressurized water reactor, began construction in August 1964, entered commercial operation on January 1, 1968, and was shut down on November 30, 1992. Units 2 and 3 are Combustion Engineering two-loop pressurized water reactors that entered commercial operation on August 8, 1983, and April 1, 1984. In January 2012 both units went offline after premature wear was found in replacement steam generators installed in 2010 and 2011, and Unit 3 had a radioactive leak on January 31, 2012. Southern California Edison announced the permanent retirement of Units 2 and 3 in June 2013.
Facility Statistics
Key performance and lifecycle metrics calculated from NRC operational data. Includes operating age, construction timeline, capacity factor, efficiency, generation totals, and reliability records.
San Onofre 3 has operated for about 27.8 years and averaged a 74.8% lifetime capacity factor, generating roughly 102.9 TWh of electricity. Its longest unbroken run reached 4,838 days.
Lifecycle & Tenure
Operating Age: 27.8 Yrs
Build Time: 10.5 Yrs
Lic. Remaining: N/A Yrs
Production & Power
Lifetime CF: 74.8%
Efficiency: 31.9%
Generated: 102.9 TWh
Reliability & Outages
Record Run: 4,838 Days
Refuelings: 4
Avg Startup: 15.5 Days
Ownership & Construction
The utility or company that owns and operates the facility, the architect-engineer responsible for plant design, and the primary construction contractor. Click names to view all facilities by that entity on the map.
Ownership, operation and management history
No change of owner, operator or management company on record. Our history starts in 1999.
EIX
Edison International
NYSE
$57.80
▲ +0.61 (+1.07%)
Previous Close
57.19
Day's Range
56.55 – 58.05
52-Week Range
51.10 – 81.62
Volume
2,360,656
Delayed quote as of Oct 22, 2026 3:37 PM ET.
Source: Yahoo Finance.
Full quote on Yahoo Finance
Scram History 2 events since 2011
Automatic and manual reactor scram (emergency shutdown) events reported to the NRC since 2011. Includes event dates, trip type, and average recovery time. Click the title to view the full fleet scram dashboard.
San Onofre 3 has recorded 2 reactor scrams, or emergency shutdowns, since 2011 (1 automatic, 1 manual). On average the unit was back to full power about 5 days after each trip.
Technical Specs
Reactor design specifications including type (PWR/BWR), containment design, nuclear steam supply system manufacturer, thermal and electrical power ratings, and current operational status.
Reactor Type:
PWR
Containment:
PWR-DRYAMB
NSS Supplier:
COMB CE
Turbine Supplier:
GEC TURBINE GENERATORS, LTD. IAEA
Thermal Power:
3390 MWt
Net Capacity:
1080 MWe
Gross Capacity:
1,127 MWe IAEA
Design Capacity:
1,070 MWe IAEA
Efficiency:
31.9%
Status:
Decommissioned
Lifetime Output:
215.7 TWh through 2025 IAEA
Licensing
NRC licensing history including docket number, license type and number, construction permit date, operating license issuance, commercial operation date, license renewal, and expiration date.
Docket #:
05000362
License #:
NPF-15
License Type:
OL-FP
Const. Permit:
1973-10-18
Construction Start:
1974-03-01 IAEA
Operating Lic:
1983-09-16
First Criticality:
1983-08-29 IAEA
Grid Connection:
1983-09-25 IAEA
Commercial Op:
1984-04-01
License Exp:
2013-10-18