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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.
61
Excellence
#30 of 94 ↑6
Mid Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
369
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2013-04-28 to 2014-10-11).
531
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (448 days for this 18-month cycle unit) with no trips to 0% power.
9
B2B Runs
81% toward B2B (361/448d)
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
88.1%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
18
Outages
since 1999
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Average time from first power generation (>0%) to sustained full power (≥95% for 2+ days) across the last 3 scheduled outages. Click to compare against the fleet on the Operator Efficiency Leaderboard.
4.3
Avg Startup
days (last 3)
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Average fuel utilization — percent of the designed fuel cycle that this unit consumes before refueling, derived from the historical burn-down trajectory. Higher = more efficient operator (refuels with less margin remaining; closer to coastdown). Computed as 100% minus the unit's average refuel-point fuel %, using the last 3 years where available, otherwise lifetime average. Click to compare against the fleet on the Operator Efficiency Leaderboard.
99.8%
Fuel Utilization
3yr avg
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NukeWorker's Operational Excellence Score is a composite 0–100 ranking of every active US nuclear unit across 7 publicly observable performance metrics, grouped into three sub-scores:
• Reliability — capacity factor, forced outage days, B2B avg streak
• Efficiency — fuel utilization, refuel duration
• Discipline — startup duration, scram count
Each unit's metric is converted to a percentile across the active fleet. Sub-score = average of its components; composite = average of the three sub-scores. Use the time-window toggle below to switch between 3yr / 5yr / lifetime.
• Reliability — capacity factor, forced outage days, B2B avg streak
• Efficiency — fuel utilization, refuel duration
• Discipline — startup duration, scram count
Each unit's metric is converted to a percentile across the active fleet. Sub-score = average of its components; composite = average of the three sub-scores. Use the time-window toggle below to switch between 3yr / 5yr / lifetime.
Time window
— change how far back we look
NukeWorker's
Operational
Excellence Score
Operational
Excellence Score
61/100
Mid Quartile · #30/94
5-year window
Palo Verde 1 ranks #30 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Forced Outage Days/yr (83th percentile). Weakest: B2B Avg Streak (27th percentile).
Reliability
61
Capacity factor + Forced outages + B2B streaks
Efficiency
53
Fuel utilization + Refuel duration
Discipline
69
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#19 of 61
PWR
Containment:
#16 of 48
Dry Ambient (PWR)
Cycle length:
#14 of 54
18-month cycle
Fleet rank above (30 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
73th
93.9% (higher better, Reliability)
Forced Outage Days/yr
83th
1.4d (lower better, Reliability)
B2B Avg Streak
27th
504d (higher better, Reliability)
Fuel Utilization
72th
98.5% (higher better, Efficiency)
Refuel Duration
35th
35d (lower better, Efficiency)
Startup Duration
69th
3.7d (lower better, Discipline)
Scrams (5-year)
70th
0.2/yr (lower better, Discipline)
Each dimension's percentile is computed across the active US fleet (94 units with sufficient history). Sub-score = average of its component percentiles. Composite = average of the three sub-scores. 5-year window. View full leaderboard →
Methodology
NukeWorker's Operational Excellence Score is a composite ranking that combines 7 publicly observable performance metrics into a single 0-100 number per US nuclear unit.
How it's computed: Each unit's raw value is converted to a percentile (0-100) within the 94 active US units that have at least 2 completed refueling cycles. The 7 percentiles are averaged into 3 sub-scores (Reliability, Efficiency, Discipline), and those are averaged into the final composite.
Active window — 5-year:
- Reliability — Capacity factor (5yr), forced outage days/yr (5yr), B2B avg streak (lifetime)
- Efficiency — in-cycle fuel utilization (3yr), median refuel duration (5yr)
- Discipline — robust mean startup duration, scrams/yr (5yr, annualised)
Cohort rankings: alongside the fleet rank, each unit gets ranked within its reactor type (PWR/BWR), containment design (Ice Condenser, Mark I, etc.), and cycle length (12/18/24-month). Useful for apples-to-apples comparisons.
What's excluded: subjective community ratings, confidential INPO ratings, financial metrics. We only use publicly available NRC + cycle data.
Why three windows? 5yr (default) is the industry standard. 3yr captures recent operational changes and post-pandemic recovery. Lifetime gives newer units a fair comparison and reveals long-term consistency.
Edge cases: units with fewer than 2 cycles (e.g., Vogtle 4) show "Provisional". Decommissioned units excluded.
Refresh cadence: recomputed daily. Each window cached separately.
A data-derived proxy for operational performance; not affiliated with INPO. INPO ratings are confidential and qualitative — ours is public and quantitative.
5-yr trend:
↑ +3.6 pts vs 2025
Compare Palo Verde 1 head-to-head with up to 3 other units.
Compare now
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Duration of each outage in days, shown chronologically. Green bars are scheduled refueling outages, red bars are forced/unscheduled. The orange dashed line marks the average duration. Extended outages (>180 days) and D&D periods are excluded.
Outage Duration Trend
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Days between consecutive scheduled refueling outage starts, showing operating cycle regularity. The purple dashed line marks the average cycle length. Most U.S. reactors operate on 18-month (547 day) or 24-month (730 day) cycles.
Cycle Length History
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Time in days from first power generation (>0%) to sustained full power (≥95% for 2+ consecutive days) after each scheduled refueling outage. The dashed line marks the average. Includes startup testing holds and power dips.
Startup Duration Trend
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Estimated fuel remaining in the current cycle, expressed as a percentage of the unit's typical cycle. Starts at 100% when the unit returns to power post-refuel and drops as full-power-days are burned. Days at reduced power burn fuel proportionally — so a unit with significant downtime (high burn deficit) drops slower and ends up with MORE fuel left than its calendar position would suggest. Coastdown threshold around 15%. Toggle to overlay past cycles on a normalized "days into cycle" axis to see how aggressively this unit historically burns down before refuel.
Fuel Burn Down Cycle since May 11, 2025
26.8% remaining
367 / 500 days
0.8 FPD margin
Avg refuel: 4.8%
Avg refuel (3yr): 0.2%
Deepest burn: 0.0% (1999-11 → 2001-03)
Most margin: 39.6% (2005-12 → 2007-05)
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Monthly capacity factor with outage events overlaid as red bands. Green bars show average power level per month. Toggle to Daily view for raw daily data.
Power History
| Type ⇅ | Actual Start ⇅ | Actual End ⇅ | Duration ⇅ | Days Online ⇅ | Scheduled | Delta |
|---|---|---|---|---|---|---|
|
Scheduled
|
2025-03-29 | 2025-05-10 | 43 | 504d | 2025-04-09 | -11d |
|
Scheduled
|
2023-10-07 | 2023-11-11 | 36 | 178d | 2023-10-10 | -3d |
|
Scram
# 56459
|
2023-04-09 | 2023-04-12 | 4 | 331d | - | - |
|
Scheduled
|
2022-04-09 | 2022-05-13 | 35 | 493d | 2022-04-09 | 0d |
|
Scheduled
|
2020-10-10 | 2020-12-02 | 54 | 521d | 2020-10-10 | 0d |
|
Scheduled
|
2019-04-06 | 2019-05-08 | 33 | 412d | 2019-04-05 | +1d |
|
Scram
# 53215
|
2018-02-16 | 2018-02-18 | 3 | 103d | - | - |
|
Scheduled
|
2017-10-07 | 2017-11-05 | 30 | 390d | 2017-10-07 | 0d |
|
Scram
# 52226
|
2016-09-08 | 2016-09-12 | 5 | 117d | - | - |
|
Scheduled
|
2016-04-09 | 2016-05-14 | 36 | 515d | 2016-04-09 | 0d |
|
Scheduled
|
2014-10-11 | 2014-11-11 | 32 | 531d | 2014-10-11 | 0d |
|
Scheduled
|
2013-03-30 | 2013-04-28 | 30 | 489d | 2013-03-30 | 0d |
|
Scheduled
|
2011-10-08 | 2011-11-27 | 51 | 59d | 2011-10-08 | 0d |
|
Scram
# 47133
|
2011-08-07 | 2011-08-10 | 4 | 442d | - | - |
|
Scheduled
|
2010-04-03 | 2010-05-22 | 50 | 15d | 2010-03-20 | +14d |
|
Unscheduled
|
2010-03-08 | 2010-03-19 | 12 | 476d | - | - |
|
Scheduled
|
2008-10-05 | 2008-11-17 | 44 | 119d | 2008-10-04 | +1d |
|
Unscheduled
|
2008-06-07 | 2008-06-08 | 2 | 191d | - | - |
|
Unscheduled
|
2007-11-24 | 2007-11-29 | 6 | 23d | - | - |
|
Unscheduled
|
2007-10-23 | 2007-11-01 | 10 | 97d | - | - |
|
Scheduled
|
2007-05-19 | 2007-07-18 | 61 | 209d | 2007-05-18 | +1d |
|
Unscheduled
|
2006-10-22 | 2006-10-22 | 1 | 7d | - | - |
|
Unscheduled
|
2006-09-20 | 2006-10-15 | 26 | 75d | - | - |
|
Unscheduled
|
2006-03-18 | 2006-07-07 | 112 | 57d | - | - |
|
Unscheduled
|
2006-01-18 | 2006-01-20 | 3 | 27d | - | - |
|
Scheduled
SGR/Major
|
2005-10-08 | 2005-12-22 | 76 | 41d | 2005-10-07 | +1d |
|
Unscheduled
|
2005-08-13 | 2005-08-28 | 16 | 145d | - | - |
|
Unscheduled
|
2005-03-19 | 2005-03-21 | 3 | 28d | - | - |
|
Unscheduled
|
2005-02-10 | 2005-02-19 | 10 | 237d | - | - |
|
Unscheduled
|
2004-06-15 | 2004-06-18 | 4 | 36d | - | - |
|
Scheduled
|
2004-04-03 | 2004-05-10 | 38 | 56d | 2004-04-02 | +1d |
|
Unscheduled
|
2004-02-04 | 2004-02-07 | 4 | 178d | - | - |
|
Unscheduled
|
2003-08-10 | 2003-08-10 | 1 | 132d | - | - |
|
Unscheduled
|
2003-03-28 | 2003-03-31 | 4 | 136d | - | - |
|
Unscheduled
|
2002-11-11 | 2002-11-12 | 2 | 10d | - | - |
|
Unscheduled
|
2002-11-01 | 2002-11-01 | 1 | 2d | - | - |
|
Scheduled
|
2002-09-28 | 2002-10-30 | 33 | 503d | 2002-09-28 | 0d |
|
Scheduled
|
2001-03-31 | 2001-05-13 | 44 | 510d | 2001-03-31 | 0d |
|
Scheduled
|
1999-10-02 | 1999-11-07 | 37 | 204d | 1999-10-02 | 0d |
|
Unscheduled
|
1999-03-11 | 1999-03-12 | 2 | - | - | - |
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