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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.
29
Excellence
#80 of 94 ↓4
Bottom Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
114
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2022-11-11 to 2024-03-23).
498
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (449 days for this 18-month cycle unit) with no trips to 0% power.
4
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
83.5%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
17
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
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.
98.9%
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
29/100
Bottom Quartile · #80/94
5-year window
D.C. Cook 2 ranks #80 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Fuel Utilization (60th percentile). Weakest: B2B Avg Streak (3th percentile).
Reliability
26
Capacity factor + Forced outages + B2B streaks
Efficiency
41
Fuel utilization + Refuel duration
Discipline
20
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#55 of 61
PWR
Containment:
#7 of 10
Ice Condenser
Cycle length:
#47 of 54
18-month cycle
Fleet rank above (80 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
48th
90.9% (higher better, Reliability)
Forced Outage Days/yr
27th
6.8d (lower better, Reliability)
B2B Avg Streak
3th
479d (higher better, Reliability)
Fuel Utilization
60th
98.2% (higher better, Efficiency)
Refuel Duration
23th
38d (lower better, Efficiency)
Startup Duration
33th
5.4d (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:
↓ -3.2 pts vs 2025
Compare D.C. Cook 2 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 Oct 25, 2025
60.8% remaining
200 / 498 days
4.6 FPD margin
Avg refuel: 3.6%
Avg refuel (3yr): 1.1%
Deepest burn: 0.0% (2009-05 → 2010-10)
Most margin: 16.1% (2017-01 → 2018-03)
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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 |
|---|---|---|---|---|---|---|
|
Scram
# 58121
|
2026-01-18 | 2026-01-20 | 3 | 86d | - | - |
|
Scheduled
|
2025-09-20 | 2025-10-24 | 35 | 446d | 2025-10-10 | -20d |
|
Unscheduled
|
2024-06-28 | 2024-07-01 | 4 | 43d | - | - |
|
Scram
# 57128
|
2024-05-16 | 2024-05-16 | 1 | 13d | - | - |
|
Scheduled
|
2024-03-23 | 2024-05-03 | 42 | 498d | 2024-03-22 | +1d |
|
Scram
# 56216
|
2022-11-11 | 2022-11-11 | 1 | 3d | - | - |
|
Scheduled
|
2022-10-01 | 2022-11-08 | 39 | 451d | 2022-10-01 | 0d |
|
Scram
# 55322
|
2021-06-23 | 2021-07-07 | 15 | 35d | - | - |
|
Scheduled
|
2021-04-17 | 2021-05-19 | 33 | 186d | 2021-04-17 | 0d |
|
Scram
# 54944
|
2020-10-12 | 2020-10-13 | 2 | 35d | - | - |
|
Scram
# 54885
|
2020-09-05 | 2020-09-07 | 3 | 118d | - | - |
|
Unscheduled
|
2020-05-02 | 2020-05-10 | 9 | 166d | - | - |
|
Scheduled
|
2019-10-03 | 2019-11-18 | 47 | 71d | 2019-10-02 | +1d |
|
Scram
# 54176
|
2019-07-22 | 2019-07-24 | 3 | 438d | - | - |
|
Scheduled
|
2018-03-01 | 2018-05-10 | 71 | 424d | 2018-03-29 | -28d |
|
Scheduled
SGR/Major
|
2016-10-05 | 2017-01-01 | 89 | 85d | 2016-10-05 | 0d |
|
Scram
# 52065
|
2016-07-06 | 2016-07-12 | 7 | 436d | - | - |
|
Scheduled
|
2015-03-25 | 2015-04-27 | 34 | 135d | 2015-03-24 | +1d |
|
Scram
# 50587
|
2014-11-01 | 2014-11-10 | 10 | 355d | - | - |
|
Scram
# 50587
|
2014-11-01 | 2014-11-10 | 10 | 9d | - | - |
|
Scheduled
|
2013-10-02 | 2013-11-11 | 41 | 64d | 2013-10-02 | 0d |
|
Scram
# 49220
|
2013-07-29 | 2013-07-30 | 2 | 454d | - | - |
|
Scram
# 47881
|
2012-05-01 | 2012-05-01 | 1 | 3d | - | - |
|
Scheduled
|
2012-03-21 | 2012-04-28 | 39 | 473d | 2012-03-12 | +9d |
|
Scheduled
|
2010-10-06 | 2010-12-04 | 60 | 425d | 2010-10-06 | 0d |
|
Unscheduled
|
2009-07-27 | 2009-08-07 | 12 | 89d | - | - |
|
Scheduled
|
2009-03-25 | 2009-04-29 | 36 | 218d | 2009-03-02 | +23d |
|
Unscheduled
|
2008-08-18 | 2008-08-19 | 2 | 287d | - | - |
|
Scheduled
|
2007-09-15 | 2007-11-05 | 52 | 497d | 2007-09-15 | 0d |
|
Scheduled
|
2006-03-25 | 2006-05-06 | 43 | 135d | 2006-03-24 | +1d |
|
Unscheduled
|
2005-11-08 | 2005-11-10 | 3 | 46d | - | - |
|
Unscheduled
|
2005-09-23 | 2005-09-23 | 1 | 244d | - | - |
|
Unscheduled
|
2005-01-22 | 2005-01-22 | 1 | 55d | - | - |
|
Unscheduled
|
2004-11-23 | 2004-11-28 | 6 | 15d | - | - |
|
Scheduled
|
2004-10-02 | 2004-11-08 | 38 | 173d | 2004-10-01 | +1d |
|
Unscheduled
|
2004-04-09 | 2004-04-12 | 4 | 7d | - | - |
|
Unscheduled
|
2004-03-30 | 2004-04-02 | 4 | 87d | - | - |
|
Unscheduled
|
2003-12-31 | 2004-01-03 | 4 | 125d | - | - |
|
Unscheduled
|
2003-08-14 | 2003-08-28 | 15 | 56d | - | - |
|
Scheduled
|
2003-04-24 | 2003-06-19 | 57 | 70d | 2003-04-24 | 0d |
|
Unscheduled
|
2003-02-06 | 2003-02-13 | 8 | 8d | - | - |
|
Unscheduled
|
2003-01-27 | 2003-01-29 | 3 | 178d | - | - |
|
Unscheduled
|
2002-07-28 | 2002-08-02 | 6 | 5d | - | - |
|
Unscheduled
|
2002-07-22 | 2002-07-23 | 2 | 51d | - | - |
|
Unscheduled
|
2002-05-26 | 2002-06-01 | 7 | 11d | - | - |
|
Unscheduled
|
2002-05-13 | 2002-05-15 | 3 | 77d | - | - |
|
Unscheduled
|
2002-01-19 | 2002-02-25 | 38 | 102d | - | - |
|
Unscheduled
|
2001-10-08 | 2001-10-09 | 2 | 2d | - | - |
|
Scheduled
|
2001-08-31 | 2001-10-06 | 37 | 217d | 2001-08-31 | 0d |
|
Unscheduled
|
2001-01-24 | 2001-01-26 | 3 | 216d | - | - |
|
Unscheduled
|
1999-01-01 | 2000-06-22 | 539 | - | - | - |
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