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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.
54
Excellence
#39 of 94 ↓11
Mid Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
42
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2020-03-31 to 2021-09-12).
530
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (451 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).
92.7%
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.
2.7
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.
98.8%
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
54/100
Mid Quartile · #39/94
5-year window
Vogtle 1 ranks #39 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Refuel Duration (75th percentile). Weakest: Scrams (5-year) (30th percentile).
Reliability
46
Capacity factor + Forced outages + B2B streaks
Efficiency
64
Fuel utilization + Refuel duration
Discipline
51
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#27 of 61
PWR
Containment:
#22 of 48
Dry Ambient (PWR)
Cycle length:
#21 of 54
18-month cycle
Fleet rank above (39 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
42th
90.1% (higher better, Reliability)
Forced Outage Days/yr
63th
2.6d (lower better, Reliability)
B2B Avg Streak
33th
506d (higher better, Reliability)
Fuel Utilization
53th
98.1% (higher better, Efficiency)
Refuel Duration
75th
25d (lower better, Efficiency)
Startup Duration
72th
3.6d (lower better, Discipline)
Scrams (5-year)
30th
0.6/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:
↓ -4.4 pts vs 2025
Compare Vogtle 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 Apr 3, 2026
92.3% remaining
40 / 512 days
0.5 FPD margin
Avg refuel: 1.4%
Avg refuel (3yr): 1.2%
Deepest burn: 0.0% (1999-03 → 2000-09)
Most margin: 4.9% (2006-10 → 2008-03)
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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
|
2026-02-22 | 2026-04-02 | 40 | 269d | 2026-02-21 | +1d |
|
Scram
# 57734
|
2025-05-29 | 2025-05-29 | 1 | 239d | - | - |
|
Scheduled
|
2024-09-08 | 2024-10-02 | 25 | 381d | 2024-09-08 | 0d |
|
Scram
# 56692
|
2023-08-23 | 2023-08-24 | 2 | 56d | - | - |
|
Unscheduled
|
2023-06-24 | 2023-06-28 | 5 | 86d | - | - |
|
Scheduled
|
2023-03-05 | 2023-03-30 | 26 | 305d | 2023-03-12 | -7d |
|
Scram
# 55875
|
2022-05-04 | 2022-05-04 | 1 | 209d | - | - |
|
Scheduled
|
2021-09-12 | 2021-10-07 | 26 | 530d | 2021-09-19 | -7d |
|
Scheduled
|
2020-03-09 | 2020-03-31 | 23 | 520d | 2020-03-09 | 0d |
|
Scheduled
|
2018-09-17 | 2018-10-06 | 20 | 75d | 2018-09-16 | +1d |
|
Scram
# 53484
|
2018-07-04 | 2018-07-04 | 1 | 457d | - | - |
|
Scheduled
|
2017-03-13 | 2017-04-03 | 22 | 35d | 2017-03-12 | +1d |
|
Unscheduled
|
2017-02-04 | 2017-02-06 | 3 | 466d | - | - |
|
Unscheduled
|
2015-10-27 | 2015-10-27 | 1 | 6d | - | - |
|
Scheduled
|
2015-09-21 | 2015-10-21 | 31 | 416d | 2015-09-20 | +1d |
|
Unscheduled
|
2014-07-31 | 2014-08-01 | 2 | 2d | - | - |
|
Scram
# 50314
|
2014-07-28 | 2014-07-29 | 2 | 106d | - | - |
|
Scram
# 50031
|
2014-04-13 | 2014-04-13 | 1 | 2d | - | - |
|
Scheduled
|
2014-03-17 | 2014-04-11 | 26 | 516d | 2014-03-16 | +1d |
|
Scheduled
|
2012-09-17 | 2012-10-17 | 31 | 155d | 2012-09-16 | +1d |
|
Scram
# 47836
|
2012-04-15 | 2012-04-15 | 1 | 227d | - | - |
|
Scram
# 47224
|
2011-09-01 | 2011-09-01 | 1 | 131d | - | - |
|
Scram
# 46772
|
2011-04-21 | 2011-04-23 | 3 | 21d | - | - |
|
Scheduled
|
2011-03-07 | 2011-03-31 | 25 | 452d | 2011-03-06 | +1d |
|
Unscheduled
|
2009-12-10 | 2009-12-10 | 1 | 2d | - | - |
|
Unscheduled
|
2009-12-08 | 2009-12-08 | 1 | 52d | - | - |
|
Scheduled
|
2009-09-21 | 2009-10-17 | 27 | 517d | 2009-09-20 | +1d |
|
Scheduled
|
2008-03-16 | 2008-04-22 | 38 | 504d | 2008-03-16 | 0d |
|
Scheduled
|
2006-09-17 | 2006-10-29 | 43 | 147d | 2006-09-16 | +1d |
|
Unscheduled
|
2006-04-17 | 2006-04-23 | 7 | 181d | - | - |
|
Unscheduled
|
2005-10-18 | 2005-10-18 | 1 | 171d | - | - |
|
Unscheduled
|
2005-04-30 | 2005-04-30 | 1 | 21d | - | - |
|
Scheduled
|
2005-03-13 | 2005-04-09 | 28 | 60d | 2005-03-12 | +1d |
|
Unscheduled
|
2005-01-12 | 2005-01-12 | 1 | 289d | - | - |
|
Unscheduled
|
2004-03-28 | 2004-03-29 | 2 | 159d | - | - |
|
Scheduled
|
2003-09-28 | 2003-10-21 | 24 | 141d | 2003-09-28 | 0d |
|
Unscheduled
|
2003-05-10 | 2003-05-10 | 1 | 160d | - | - |
|
Unscheduled
|
2002-11-25 | 2002-12-01 | 7 | 221d | - | - |
|
Scheduled
|
2002-03-06 | 2002-04-18 | 44 | 193d | 2002-03-06 | 0d |
|
Unscheduled
|
2001-08-25 | 2001-08-25 | 1 | 258d | - | - |
|
Unscheduled
|
2000-12-10 | 2000-12-10 | 1 | 54d | - | - |
|
Scheduled
|
2000-09-17 | 2000-10-17 | 31 | 103d | 2000-09-17 | 0d |
|
Unscheduled
|
2000-06-06 | 2000-06-06 | 1 | 439d | - | - |
|
Scheduled
|
1999-02-28 | 1999-03-25 | 26 | - | 1999-02-28 | 0d |
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