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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.
46
Excellence
#58 of 94 →
Mid Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
557
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2020-11-03 to 2022-10-02).
698
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (617 days for this 24-month cycle unit) with no trips to 0% power.
3
B2B Runs
89% toward B2B (549/617d)
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
89.5%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
15
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.
3.3
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.
83.6%
Fuel Utilization
lifetime 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
46/100
Mid Quartile · #58/94
5-year window
Cooper ranks #58 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Forced Outage Days/yr (87th percentile). Weakest: Refuel Duration (12th percentile).
Reliability
80
Capacity factor + Forced outages + B2B streaks
Efficiency
23
Fuel utilization + Refuel duration
Discipline
34
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#17 of 31
BWR
Containment:
#12 of 19
Mark I (BWR)
Cycle length:
#25 of 40
24-month cycle
Fleet rank above (58 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
80th
94.4% (higher better, Reliability)
Forced Outage Days/yr
87th
1.0d (lower better, Reliability)
B2B Avg Streak
72th
676d (higher better, Reliability)
Fuel Utilization
34th
97.3% (higher better, Efficiency)
Refuel Duration
12th
42d (lower better, Efficiency)
Startup Duration
20th
6.5d (lower better, Discipline)
Scrams (5-year)
48th
0.4/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:
Stable vs 2025
Compare Cooper 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 Nov 4, 2024
19.3% remaining
554 / 681 days
4.6 FPD margin
Avg refuel: 16.4%
Deepest burn: 0.0% (2020-10 → 2022-10)
Most margin: 37.5% (2002-01 → 2003-05)
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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
|
2024-09-29 | 2024-11-03 | 36 | 650d | 2024-09-28 | +1d |
|
Scram
# 56278
|
2022-12-17 | 2022-12-19 | 3 | 34d | - | - |
|
Scheduled
|
2022-10-02 | 2022-11-13 | 43 | 698d | 2022-10-01 | +1d |
|
Unscheduled
|
2020-11-02 | 2020-11-03 | 2 | 7d | - | - |
|
Scheduled
|
2020-09-27 | 2020-10-26 | 30 | 682d | 2020-09-26 | +1d |
|
Scheduled
|
2018-09-30 | 2018-11-15 | 47 | 117d | 2018-09-29 | +1d |
|
Unscheduled
|
2018-05-30 | 2018-06-05 | 7 | 75d | - | - |
|
Unscheduled
|
2018-03-12 | 2018-03-16 | 5 | 491d | - | - |
|
Scheduled
|
2016-09-25 | 2016-11-06 | 43 | 482d | 2016-09-25 | 0d |
|
Unscheduled
|
2015-05-30 | 2015-06-01 | 3 | 210d | - | - |
|
Scheduled
|
2014-09-28 | 2014-11-01 | 35 | 116d | 2014-09-27 | +1d |
|
Unscheduled
|
2014-05-30 | 2014-06-04 | 6 | 549d | - | - |
|
Scheduled
|
2012-10-14 | 2012-11-27 | 45 | 526d | 2012-10-01 | +13d |
|
Scheduled
|
2011-03-13 | 2011-05-07 | 56 | 485d | 2011-03-12 | +1d |
|
Unscheduled
|
2009-11-12 | 2009-11-13 | 2 | 4d | - | - |
|
Unscheduled
|
2009-11-07 | 2009-11-08 | 2 | 3d | - | - |
|
Scheduled
|
2009-09-26 | 2009-11-04 | 40 | 200d | 2009-09-26 | 0d |
|
Unscheduled
|
2009-03-06 | 2009-03-10 | 5 | 207d | - | - |
|
Unscheduled
|
2008-08-09 | 2008-08-11 | 3 | 84d | - | - |
|
Scheduled
|
2008-04-12 | 2008-05-17 | 36 | 327d | 2008-04-12 | 0d |
|
Unscheduled
|
2007-05-19 | 2007-05-21 | 3 | 179d | - | - |
|
Scheduled
|
2006-10-21 | 2006-11-21 | 32 | 150d | 2006-10-20 | +1d |
|
Unscheduled
|
2006-05-23 | 2006-05-24 | 2 | 84d | - | - |
|
Unscheduled
|
2006-02-26 | 2006-02-28 | 3 | 154d | - | - |
|
Unscheduled
|
2005-09-23 | 2005-09-25 | 3 | 159d | - | - |
|
Unscheduled
|
2005-04-16 | 2005-04-17 | 2 | 58d | - | - |
|
Scheduled
|
2005-01-15 | 2005-02-17 | 34 | 69d | 2005-01-15 | 0d |
|
Unscheduled
|
2004-10-20 | 2004-11-07 | 19 | 322d | - | - |
|
Unscheduled
|
2003-11-29 | 2003-12-03 | 5 | 27d | - | - |
|
Unscheduled
|
2003-10-28 | 2003-11-02 | 6 | 120d | - | - |
|
Scheduled
|
2003-05-27 | 2003-06-30 | 35 | 35d | 2003-05-27 | 0d |
|
Unscheduled
|
2003-04-21 | 2003-04-22 | 2 | 6d | - | - |
|
Unscheduled
|
2003-02-24 | 2003-04-15 | 51 | 280d | - | - |
|
Unscheduled
|
2002-05-15 | 2002-05-20 | 6 | 137d | - | - |
|
Scheduled
|
2001-11-04 | 2001-12-29 | 56 | 233d | 2001-11-04 | 0d |
|
Unscheduled
|
2001-03-16 | 2001-03-16 | 1 | 3d | - | - |
|
Unscheduled
|
2001-03-04 | 2001-03-13 | 10 | 137d | - | - |
|
Unscheduled
|
2000-10-14 | 2000-10-18 | 5 | 140d | - | - |
|
Scheduled
SGR/Major
|
2000-03-04 | 2000-05-27 | 85 | 50d | 2000-03-04 | 0d |
|
Unscheduled
|
2000-01-09 | 2000-01-14 | 6 | 107d | - | - |
|
Unscheduled
|
1999-09-18 | 1999-09-24 | 7 | - | - | - |
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