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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.
42
Excellence
#65 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).
181
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2005-05-18 to 2006-10-07).
507
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (446 days for this 18-month cycle unit) with no trips to 0% power.
6
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
87.2%
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.
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.
99.1%
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
42/100
Mid Quartile · #65/94
5-year window
Wolf Creek 1 ranks #65 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Startup Duration (83th percentile). Weakest: Refuel Duration (11th percentile).
Reliability
31
Capacity factor + Forced outages + B2B streaks
Efficiency
29
Fuel utilization + Refuel duration
Discipline
66
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#45 of 61
PWR
Containment:
#38 of 48
Dry Ambient (PWR)
Cycle length:
#38 of 54
18-month cycle
Fleet rank above (65 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
33th
89.2% (higher better, Reliability)
Forced Outage Days/yr
49th
3.8d (lower better, Reliability)
B2B Avg Streak
12th
496d (higher better, Reliability)
Fuel Utilization
46th
97.9% (higher better, Efficiency)
Refuel Duration
11th
43d (lower better, Efficiency)
Startup Duration
83th
3.3d (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 Wolf Creek 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 Nov 16, 2025
65.1% remaining
178 / 507 days
0.8 FPD margin
Avg refuel: 7.8%
Avg refuel (3yr): 0.9%
Deepest burn: 0.0% (2002-04 → 2003-10)
Most margin: 44.1% (2013-04 → 2014-03)
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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
|
2025-10-02 | 2025-11-14 | 44 | 402d | 2025-09-25 | +7d |
|
Unscheduled
|
2024-08-24 | 2024-08-26 | 3 | 106d | - | - |
|
Scheduled
|
2024-03-28 | 2024-05-10 | 44 | 494d | 2024-03-27 | +1d |
|
Scheduled
|
2022-10-06 | 2022-11-20 | 46 | 77d | 2022-10-06 | 0d |
|
Scram
# 56005
|
2022-07-19 | 2022-07-21 | 3 | 332d | - | - |
|
Scram
# 55416
|
2021-08-19 | 2021-08-21 | 3 | 69d | - | - |
|
Unscheduled
|
2021-06-06 | 2021-06-11 | 6 | 24d | - | - |
|
Scheduled
|
2021-03-25 | 2021-05-13 | 50 | 416d | 2021-03-25 | 0d |
|
Unscheduled
|
2020-02-02 | 2020-02-03 | 2 | 88d | - | - |
|
Scheduled
|
2019-09-21 | 2019-11-06 | 47 | 492d | 2019-09-21 | 0d |
|
Scheduled
|
2018-03-31 | 2018-05-17 | 48 | 496d | 2018-03-17 | +14d |
|
Scheduled
|
2016-09-03 | 2016-11-20 | 79 | 491d | 2016-09-24 | -21d |
|
Scheduled
|
2015-02-28 | 2015-05-01 | 63 | 291d | 2015-02-28 | 0d |
|
Scheduled
|
2014-03-08 | 2014-05-13 | 67 | 132d | 2014-02-01 | +35d |
|
Unscheduled
|
2013-10-19 | 2013-10-27 | 9 | 20d | - | - |
|
Unscheduled
|
2013-09-12 | 2013-09-29 | 18 | 123d | - | - |
|
Unscheduled
|
2013-05-07 | 2013-05-12 | 6 | 24d | - | - |
|
Scheduled
|
2013-02-04 | 2013-04-13 | 69 | 315d | 2013-02-04 | 0d |
|
Scram
# 47590
|
2012-01-14 | 2012-03-26 | 73 | 199d | - | - |
|
Scram
# 46990
|
2011-06-27 | 2011-06-29 | 3 | 5d | - | - |
|
Scheduled
SGR/Major
|
2011-03-19 | 2011-06-22 | 96 | 101d | 2011-03-19 | 0d |
|
Unscheduled
|
2010-12-07 | 2010-12-08 | 2 | 50d | - | - |
|
Unscheduled
|
2010-10-18 | 2010-10-18 | 1 | 2d | - | - |
|
Unscheduled
|
2010-10-06 | 2010-10-16 | 11 | 211d | - | - |
|
Unscheduled
|
2010-03-09 | 2010-03-09 | 1 | 2d | - | - |
|
Unscheduled
|
2010-03-03 | 2010-03-07 | 5 | 103d | - | - |
|
Scheduled
|
2009-10-10 | 2009-11-20 | 42 | 48d | 2009-09-19 | +21d |
|
Unscheduled
|
2009-08-20 | 2009-08-23 | 4 | 112d | - | - |
|
Unscheduled
|
2009-04-29 | 2009-04-30 | 2 | 351d | - | - |
|
Scheduled
|
2008-03-18 | 2008-05-13 | 57 | 63d | 2008-03-22 | -4d |
|
Unscheduled
|
2008-01-12 | 2008-01-15 | 4 | 429d | - | - |
|
Scheduled
|
2006-10-07 | 2006-11-09 | 34 | 507d | 2006-10-06 | +1d |
|
Scheduled
|
2005-04-09 | 2005-05-18 | 40 | 67d | 2005-04-08 | +1d |
|
Unscheduled
|
2005-01-24 | 2005-02-01 | 9 | 108d | - | - |
|
Unscheduled
|
2004-10-08 | 2004-10-08 | 1 | 46d | - | - |
|
Unscheduled
|
2004-08-23 | 2004-08-23 | 1 | 190d | - | - |
|
Unscheduled
|
2004-02-14 | 2004-02-15 | 2 | 74d | - | - |
|
Scheduled
|
2003-10-18 | 2003-12-02 | 46 | 59d | 2003-10-18 | 0d |
|
Unscheduled
|
2003-08-19 | 2003-08-20 | 2 | 227d | - | - |
|
Unscheduled
|
2003-01-04 | 2003-01-04 | 1 | 230d | - | - |
|
Unscheduled
|
2002-05-14 | 2002-05-19 | 6 | 5d | - | - |
|
Unscheduled
|
2002-05-09 | 2002-05-09 | 1 | 13d | - | - |
|
Scheduled
|
2002-03-23 | 2002-04-26 | 35 | 502d | 2002-03-23 | 0d |
|
Scheduled
|
2000-09-30 | 2000-11-06 | 38 | 25d | 2000-09-30 | 0d |
|
Unscheduled
|
2000-09-05 | 2000-09-05 | 1 | 396d | - | - |
|
Unscheduled
|
1999-08-06 | 1999-08-06 | 1 | 91d | - | - |
|
Scheduled
|
1999-04-03 | 1999-05-07 | 35 | - | 1999-04-03 | 0d |
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