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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.
64
Excellence
#26 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).
193
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2010-11-10 to 2012-04-21).
528
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (458 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).
91.5%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
18
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.
2.3
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
64/100
Mid Quartile · #26/94
5-year window
Harris 1 ranks #26 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Fuel Utilization (92th percentile). Weakest: Scrams (5-year) (16th percentile).
Reliability
61
Capacity factor + Forced outages + B2B streaks
Efficiency
78
Fuel utilization + Refuel duration
Discipline
53
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#16 of 61
PWR
Containment:
#14 of 48
Dry Ambient (PWR)
Cycle length:
#11 of 54
18-month cycle
Fleet rank above (26 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
74th
94.0% (higher better, Reliability)
Forced Outage Days/yr
59th
2.8d (lower better, Reliability)
B2B Avg Streak
49th
515d (higher better, Reliability)
Fuel Utilization
92th
99.1% (higher better, Efficiency)
Refuel Duration
63th
29d (lower better, Efficiency)
Startup Duration
90th
3.1d (lower better, Discipline)
Scrams (5-year)
16th
0.8/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 Harris 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 3, 2025
62.8% remaining
190 / 510 days
0.5 FPD margin
Avg refuel: 2.6%
Avg refuel (3yr): 0.9%
Deepest burn: 0.0% (2007-10 → 2009-04)
Most margin: 9.3% (2013-12 → 2015-04)
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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
|
2025-10-04 | 2025-11-02 | 30 | 490d | 2025-10-04 | 0d |
|
Scram
# 57155
|
2024-05-31 | 2024-06-01 | 2 | 19d | - | - |
|
Scheduled
|
2024-04-10 | 2024-05-12 | 33 | 525d | 2024-04-12 | -2d |
|
Scheduled
|
2022-10-08 | 2022-11-02 | 26 | 40d | 2022-10-08 | 0d |
|
Scram
# 56075
|
2022-08-28 | 2022-08-29 | 2 | 120d | - | - |
|
Scram
# 55868
|
2022-04-29 | 2022-04-30 | 2 | 326d | - | - |
|
Unscheduled
|
2021-06-05 | 2021-06-07 | 3 | 21d | - | - |
|
Unscheduled
Startup Hold
|
2021-05-15 | 2021-05-15 | 1 | 2d | - | - |
|
Scheduled
|
2021-04-24 | 2021-05-13 | 20 | 124d | 2021-04-24 | 0d |
|
Scram
# 55038
|
2020-12-17 | 2020-12-21 | 5 | 124d | - | - |
|
Scram
# 54834
|
2020-08-14 | 2020-08-15 | 2 | 143d | - | - |
|
Scram
# 54599
|
2020-03-24 | 2020-03-24 | 1 | 128d | - | - |
|
Scheduled
|
2019-10-12 | 2019-11-17 | 37 | 521d | 2019-10-12 | 0d |
|
Scheduled
|
2018-04-07 | 2018-05-09 | 33 | 80d | 2018-04-07 | 0d |
|
Unscheduled
|
2018-01-15 | 2018-01-17 | 3 | 83d | - | - |
|
Unscheduled
|
2017-10-23 | 2017-10-24 | 2 | 348d | - | - |
|
Scheduled
|
2016-10-10 | 2016-11-09 | 31 | 2d | 2016-10-08 | +2d |
|
Scram
# 52289
|
2016-10-08 | 2016-10-08 | 1 | 512d | - | - |
|
Scheduled
|
2015-04-02 | 2015-05-15 | 44 | 316d | 2015-03-28 | +5d |
|
Unscheduled
|
2014-05-16 | 2014-05-21 | 6 | 115d | - | - |
|
Scram
# 49742
|
2014-01-19 | 2014-01-21 | 3 | 40d | - | - |
|
Scheduled
|
2013-11-09 | 2013-12-10 | 32 | 156d | 2013-11-02 | +7d |
|
Unscheduled
|
2013-05-16 | 2013-06-06 | 22 | 344d | - | - |
|
Scheduled
|
2012-04-21 | 2012-06-06 | 47 | 528d | 2012-04-21 | 0d |
|
Scheduled
|
2010-10-02 | 2010-11-10 | 40 | 316d | 2010-10-02 | 0d |
|
Unscheduled
|
2009-11-16 | 2009-11-20 | 5 | 191d | - | - |
|
Scheduled
|
2009-04-18 | 2009-05-09 | 22 | 241d | 2009-04-18 | 0d |
|
Unscheduled
|
2008-08-11 | 2008-08-20 | 10 | 294d | - | - |
|
Scheduled
|
2007-09-29 | 2007-10-22 | 24 | 373d | 2007-09-29 | 0d |
|
Unscheduled
|
2006-09-20 | 2006-09-21 | 2 | 124d | - | - |
|
Unscheduled
|
2006-05-19 | 2006-05-19 | 1 | 4d | - | - |
|
Scheduled
|
2006-04-09 | 2006-05-15 | 37 | 342d | 2006-04-08 | +1d |
|
Unscheduled
|
2005-05-01 | 2005-05-02 | 2 | 166d | - | - |
|
Unscheduled
|
2004-11-09 | 2004-11-16 | 8 | 2d | - | - |
|
Scheduled
|
2004-10-16 | 2004-11-07 | 23 | 150d | 2004-10-15 | +1d |
|
Unscheduled
|
2004-05-07 | 2004-05-19 | 13 | 263d | - | - |
|
Unscheduled
|
2003-08-18 | 2003-08-18 | 1 | 64d | - | - |
|
Unscheduled
|
2003-06-15 | 2003-06-15 | 1 | 27d | - | - |
|
Unscheduled
Startup Hold
|
2003-05-19 | 2003-05-19 | 1 | 2d | - | - |
|
Scheduled
|
2003-04-26 | 2003-05-17 | 22 | 253d | 2003-04-26 | 0d |
|
Unscheduled
|
2002-08-16 | 2002-08-16 | 1 | 34d | - | - |
|
Unscheduled
|
2002-07-13 | 2002-07-13 | 1 | 192d | - | - |
|
Unscheduled
|
2002-01-02 | 2002-01-02 | 1 | 2d | - | - |
|
Scheduled
SGR/Major
|
2001-09-22 | 2001-12-31 | 101 | 458d | 2001-09-22 | 0d |
|
Unscheduled
|
2000-06-21 | 2000-06-21 | 1 | 41d | - | - |
|
Scheduled
|
2000-04-15 | 2000-05-11 | 27 | 123d | 2000-04-15 | 0d |
|
Unscheduled
|
1999-12-14 | 1999-12-14 | 1 | 272d | - | - |
|
Unscheduled
|
1999-03-13 | 1999-03-17 | 5 | 57d | - | - |
|
Unscheduled
|
1999-01-15 | 1999-01-15 | 1 | - | - | - |
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