Diablo Canyon 1
Refueling Outage · Day 5Pacific Gas & Electric·Avila Beach, CA·PWR·1,122 MWe
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Composite Operational Excellence Score (0-100) — average percentile rank across 7 dimensions in three sub-scores: Reliability (capacity factor, forced outage days, B2B avg streak), Efficiency (fuel utilization, refuel duration), and Discipline (startup duration, scram count). 5-year window. Higher = more operationally excellent. Click to see the full breakdown.
Excellence
Rank locked · 93 units
Subscribers
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Current reactor power level from the most recent NRC daily report.
0%
Power
OFFLINE (5 Days)
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Days of continuous operation since the last outage ended. Ranked against all operating units.
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Current Run
offline
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Longest recorded period of continuous operation between outages.
667
Record Run
days
#44 of 95
Mid Quartile
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (455 days for this 18-month cycle unit) with no trips to 0% power.
12
B2B Runs
#5 of 85
Top Quartile
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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.
90.2%
Capacity Factor
#48 of 95
Mid Quartile
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Net electricity actually generated over the most recent 12 months reported by the U.S. Energy Information Administration (Form EIA-923), summed across every unit at this plant. These are authoritative actuals, not an estimate.
18.29 TWh
Net Generation
EIA-923 · 12 mo to 2026-07 · plant total
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Total NRC-reported scram events (emergency reactor shutdowns). Ranked fleet-wide — fewer scrams = better rank.
1
Scrams
#5 of 94
Top Quartile
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Years since commercial operation began. License remaining: 38 years.
41.4
Operating Age
years
38 yrs remaining
Excellence Score, Records & Plant Facts
Breaker-to-Breaker Runs 12 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.
Diablo Canyon 1 has logged 12 breaker-to-breaker runs, continuous stretches from one refueling to the next with no trip to zero power. Its longest ran 598 days, and its runs average 520 days.
598
Best Run (days)
1R20 (2017-06-22) → 1R21 (2019-02-10)
520
Avg Run (days)
★ 6-run breaker-to-breaker
1R19 → 1R20 → 1R21 → 1R22 → 1R23 → 1R24 → 1R25
All Runs
| 2023-12-17 | 2025-04-13 | 483 days | 1R24 → 1R25 |
| 2022-04-22 | 2023-10-01 | 527 days | 1R23 → 1R24 |
| 2020-11-02 | 2022-03-27 | 510 days | 1R22 → 1R23 |
| 2019-03-17 | 2020-10-04 | 567 days | 1R21 → 1R22 |
| 2017-06-22 | 2019-02-10 | 598 days | 1R20 → 1R21 |
| 2015-11-08 | 2017-04-23 | 532 days | 1R19 → 1R20 |
| 2010-11-11 | 2012-04-23 | 529 days | 1R16 → 1R17 |
| 2007-08-16 | 2009-01-26 | 529 days | 1R14 → 1R15 |
| 2005-11-30 | 2007-05-01 | 517 days | 1R13 → 1R14 |
| 2004-07-24 | 2005-10-24 | 457 days | 1R12 → 1R13 |
| 2002-12-12 | 2004-03-23 | 467 days | 1R11 → 1R12 |
| 2000-11-22 | 2002-04-29 | 523 days | 1R10 → 1R11 |
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: Diablo Canyon Power Plant.
Diablo Canyon Power Plant is a two-unit nuclear station on the Pacific coast near Avila Beach, in San Luis Obispo County, California, on about 750 acres.
Read more
Pacific Gas and Electric began construction of Unit 1 on April 23, 1968, and Unit 2 on December 9, 1970. Both are Westinghouse four-loop pressurized water reactors. Unit 1 was first connected to the grid on November 11, 1984, and Unit 2 on October 20, 1985. The NRC approved the plant's safety in 1978. In 1981 about 1,900 protesters were arrested over two weeks, and in September 1981 PG&E found that one set of blueprints had been used for structural supports in both reactors.
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.
Diablo Canyon 1 has operated for about 41.4 years and averaged a 90.2% lifetime capacity factor, generating roughly 246.4 TWh of electricity. Its longest unbroken run reached 667 days.
Lifecycle & Tenure
Operating Age: 41.4 Yrs
Build Time: 17 Yrs
Lic. Remaining: 38 Yrs
Production & Power
Lifetime CF: 90.2%
Efficiency: 32.9%
Generated: 246.4 TWh
Reliability & Outages
Record Run: 667 Days
Refuelings: 18
Avg Startup: 8.1 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.
PCG
PG&E Corporation
NYSE
$12.97
▼ -0.19 (-1.41%)
Previous Close
13.15
Day's Range
12.96 – 13.30
52-Week Range
11.77 – 19.16
Volume
20,002,245
Delayed quote as of Oct 15, 2026 3:53 PM ET.
Source: Yahoo Finance.
Full quote on Yahoo Finance
Operational Excellence Score Subscribers
Diablo Canyon 1 is rated 0 to 100 on how well it actually runs, scored against every other operating reactor in the US fleet from its own operating record. Subscribers see the score, the three sub-scores behind it, and each of the seven measured inputs.
- This unit's composite score and fleet rank
- Reliability, Efficiency and Discipline sub-scores
- All seven measured inputs, with fleet percentiles
- Rank against comparable units, not just the fleet
- Three-year, five-year and lifetime windows
- Five-year trend, and every other operating US reactor
Included with every outage subscription and with NukeWorker Gold membership. Trading the outage rather than working it? The same record, cut by power market, is on NukeGryd.
Scram History 1 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.
Diablo Canyon 1 has recorded 1 reactor scram, or emergency shutdown, since 2011 (0 automatic, 1 manual). On average the unit was back to full power about 49 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:
WEST 4LP
Turbine Supplier:
WESTINGHOUSE ELECTRIC CORPORATION IAEA
Thermal Power:
3411 MWt
Net Capacity:
1122 MWe
Gross Capacity:
1,197 MWe IAEA
Design Capacity:
1,084 MWe IAEA
Efficiency:
32.9%
Status:
Operating
Lifetime Output:
334.7 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 #:
05000275
License #:
DPR-80
License Type:
OL-FP
Const. Permit:
1968-04-23
Construction Start:
1968-04-23 IAEA
Operating Lic:
1984-11-02
First Criticality:
1984-04-29 IAEA
Grid Connection:
1984-11-11 IAEA
Commercial Op:
1985-05-07
License Renewed:
2026-04-02
License Exp:
2064-11-02
Market & Region
EIA market and grid-region classifications: NERC reliability region, U.S. Census region, balancing authority responsible for grid operations, and whether the unit operates as a rate-regulated utility or a competitive merchant generator. Hover any value for the full name.
NERC Region:
WECC
— Western Electricity Coordinating Council
Census Region:
PACC
— Pacific Contiguous (OR, WA, CA)
Balancing Authority:
CISO
— California Independent System Operator (ISO/RTO)
Market Structure:
Regulated
— Rate-regulated utility (cost-of-service pricing)