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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.
19
Excellence
#89 of 94 ↓4
Bottom Quartile
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Days of continuous operation since the last outage ended (Started 2026-04-09). Clean run (no forced outages since last refueling).
35
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2011-05-29 to 2012-10-13).
503
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (445 days for this 18-month cycle unit) with no trips to 0% power.
5
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
87.5%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
19
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.
5.3
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.
95.3%
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
19/100
Bottom Quartile · #89/94
5-year window
Summer ranks #89 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Startup Duration (56th percentile). Weakest: Scrams (5-year) (7th percentile).
Reliability
11
Capacity factor + Forced outages + B2B streaks
Efficiency
14
Fuel utilization + Refuel duration
Discipline
31
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#60 of 61
PWR
Containment:
#46 of 48
Dry Ambient (PWR)
Cycle length:
#52 of 54
18-month cycle
Fleet rank above (89 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
13th
84.2% (higher better, Reliability)
Forced Outage Days/yr
12th
14.2d (lower better, Reliability)
B2B Avg Streak
10th
491d (higher better, Reliability)
Fuel Utilization
12th
94.7% (higher better, Efficiency)
Refuel Duration
16th
40d (lower better, Efficiency)
Startup Duration
56th
4.1d (lower better, Discipline)
Scrams (5-year)
7th
1.0/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:
↓ -4.3 pts vs 2025
Compare Summer 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 Apr 10, 2026
93.5% remaining
33 / 483 days
1.5 FPD margin
Avg refuel: 2.2%
Avg refuel (3yr): 4.7%
Deepest burn: 0.0% (1999-05 → 2000-10)
Most margin: 17.9% (2001-03 → 2002-04)
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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
|
2026-02-28 | 2026-04-09 | 41 | 21d | 2026-02-27 | +1d |
|
Scram
# 58141
|
2026-01-31 | 2026-02-07 | 8 | 99d | - | - |
|
Scram
# 57987
|
2025-10-15 | 2025-10-24 | 10 | 7d | - | - |
|
Unscheduled
|
2025-10-04 | 2025-10-08 | 5 | 235d | - | - |
|
Scram
# 57540
|
2025-02-11 | 2025-02-11 | 1 | 78d | - | - |
|
Unscheduled
|
2024-11-20 | 2024-11-25 | 6 | 20d | - | - |
|
Scheduled
|
2024-09-21 | 2024-10-31 | 41 | 492d | 2024-09-20 | +1d |
|
Scheduled
|
2023-04-06 | 2023-05-18 | 43 | 482d | 2023-04-07 | -1d |
|
Scram
# 55580
|
2021-11-16 | 2021-12-10 | 25 | 3d | - | - |
|
Unscheduled
|
2021-11-04 | 2021-11-13 | 10 | 2d | - | - |
|
Scheduled
|
2021-10-09 | 2021-11-02 | 25 | 148d | 2021-10-21 | -12d |
|
Unscheduled
|
2021-05-13 | 2021-05-14 | 2 | 246d | - | - |
|
Unscheduled
|
2020-09-08 | 2020-09-09 | 2 | 121d | - | - |
|
Scheduled
|
2020-04-11 | 2020-05-10 | 30 | 134d | 2020-04-11 | 0d |
|
Unscheduled
|
2019-11-29 | 2019-11-29 | 1 | 10d | - | - |
|
Unscheduled
|
2019-11-08 | 2019-11-19 | 12 | 349d | - | - |
|
Scheduled
|
2018-10-06 | 2018-11-24 | 50 | 330d | 2018-10-05 | +1d |
|
Scram
# 53060
|
2017-11-08 | 2017-11-10 | 3 | 62d | - | - |
|
Scram
# 52932
|
2017-08-29 | 2017-09-07 | 10 | 59d | - | - |
|
Scram
# 52833
|
2017-06-30 | 2017-07-01 | 2 | 29d | - | - |
|
Scheduled
|
2017-04-08 | 2017-06-01 | 55 | 494d | 2017-04-07 | +1d |
|
Scheduled
|
2015-10-03 | 2015-12-01 | 60 | 438d | 2015-10-03 | 0d |
|
Unscheduled
|
2014-07-14 | 2014-07-22 | 9 | 45d | - | - |
|
Scheduled
|
2014-04-05 | 2014-05-30 | 56 | 369d | 2014-04-04 | +1d |
|
Unscheduled
|
2013-03-23 | 2013-04-01 | 10 | 107d | - | - |
|
Scheduled
|
2012-10-13 | 2012-12-06 | 55 | 503d | 2012-10-12 | +1d |
|
Scheduled
|
2011-04-16 | 2011-05-29 | 44 | 87d | 2011-04-16 | 0d |
|
Unscheduled
|
2011-01-18 | 2011-01-19 | 2 | 115d | - | - |
|
Unscheduled
|
2010-09-23 | 2010-09-25 | 3 | 280d | - | - |
|
Unscheduled
|
2009-12-17 | 2009-12-17 | 1 | 8d | - | - |
|
Scheduled
|
2009-10-17 | 2009-12-09 | 54 | 7d | 2009-10-16 | +1d |
|
Unscheduled
|
2009-10-03 | 2009-10-10 | 8 | 477d | - | - |
|
Scheduled
|
2008-04-26 | 2008-06-13 | 49 | 86d | 2008-04-25 | +1d |
|
Unscheduled
|
2008-01-25 | 2008-01-31 | 7 | 353d | - | - |
|
Unscheduled
|
2007-02-05 | 2007-02-06 | 2 | 76d | - | - |
|
Scheduled
|
2006-10-14 | 2006-11-21 | 39 | 413d | 2006-10-13 | +1d |
|
Unscheduled
|
2005-08-26 | 2005-08-27 | 2 | 86d | - | - |
|
Scheduled
|
2005-04-24 | 2005-06-01 | 39 | 378d | 2005-04-23 | +1d |
|
Unscheduled
|
2004-03-31 | 2004-04-11 | 12 | 129d | - | - |
|
Scheduled
|
2003-10-11 | 2003-11-23 | 44 | 150d | 2003-10-11 | 0d |
|
Unscheduled
|
2003-05-12 | 2003-05-14 | 3 | 328d | - | - |
|
Unscheduled
|
2002-06-18 | 2002-06-18 | 1 | 16d | - | - |
|
Scheduled
|
2002-04-20 | 2002-06-02 | 44 | 319d | 2002-04-20 | 0d |
|
Unscheduled
|
2001-06-04 | 2001-06-05 | 2 | 95d | - | - |
|
Scheduled
SGR/Major
|
2000-10-08 | 2001-03-01 | 145 | 491d | 2000-10-08 | 0d |
|
Unscheduled
|
1999-06-05 | 1999-06-05 | 1 | 18d | - | - |
|
Unscheduled
|
1999-05-18 | 1999-05-18 | 1 | 8d | - | - |
|
Scheduled
|
1999-04-04 | 1999-05-10 | 37 | - | 1999-04-04 | 0d |
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