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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.
27
Excellence
#83 of 94 ↓1
Bottom Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
10
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2008-04-16 to 2010-03-02).
685
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (610 days for this 24-month cycle unit) with no trips to 0% power.
2
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
87.9%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
14
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.
13.3
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.
96.1%
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
27/100
Bottom Quartile · #83/94
5-year window
Susquehanna 1 ranks #83 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: B2B Avg Streak (71th percentile). Weakest: Startup Duration (4th percentile).
Reliability
41
Capacity factor + Forced outages + B2B streaks
Efficiency
34
Fuel utilization + Refuel duration
Discipline
5
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#25 of 31
BWR
Containment:
#8 of 8
Mark II (BWR)
Cycle length:
#34 of 40
24-month cycle
Fleet rank above (83 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
22th
87.2% (higher better, Reliability)
Forced Outage Days/yr
31th
6.2d (lower better, Reliability)
B2B Avg Streak
71th
675d (higher better, Reliability)
Fuel Utilization
20th
96.0% (higher better, Efficiency)
Refuel Duration
47th
33d (lower better, Efficiency)
Startup Duration
4th
10.9d (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:
↓ -2.4 pts vs 2025
Compare Susquehanna 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 May 5, 2026
99.0% remaining
8 / 696 days
1.2 FPD margin
Avg refuel: 7.6%
Avg refuel (3yr): 3.9%
Deepest burn: 3.9% (2024-04 → 2026-03)
Most margin: 16.3% (2012-06 → 2014-04)
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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
|
2026-03-23 | 2026-05-04 | 43 | 127d | 2026-03-23 | 0d |
|
Unscheduled
|
2025-11-13 | 2025-11-16 | 4 | 112d | - | - |
|
Scram
# 57822
|
2025-07-23 | 2025-07-24 | 2 | 314d | - | - |
|
Unscheduled
|
2024-09-09 | 2024-09-12 | 4 | 138d | - | - |
|
Scheduled
|
2024-03-25 | 2024-04-24 | 31 | 132d | 2024-03-24 | +1d |
|
Scram
# 56846
|
2023-11-10 | 2023-11-14 | 5 | 534d | - | - |
|
Scram
# 55909
|
2022-05-24 | 2022-05-25 | 2 | 24d | - | - |
|
Scheduled
|
2022-03-28 | 2022-04-30 | 34 | 112d | 2022-03-28 | 0d |
|
Scram
# 55616
|
2021-12-01 | 2021-12-06 | 6 | 128d | - | - |
|
Scram
# 55370
|
2021-07-22 | 2021-07-26 | 5 | 441d | - | - |
|
Scram
# 54691
|
2020-05-04 | 2020-05-07 | 4 | 3d | - | - |
|
Unscheduled
|
2020-04-29 | 2020-05-01 | 3 | 6d | - | - |
|
Scheduled
|
2020-03-28 | 2020-04-23 | 27 | 583d | 2020-03-27 | +1d |
|
Unscheduled
|
2018-08-19 | 2018-08-23 | 5 | 110d | - | - |
|
Scheduled
|
2018-03-31 | 2018-05-01 | 32 | 295d | 2018-04-30 | -30d |
|
Scram
# 52795
|
2017-06-09 | 2017-06-09 | 1 | 347d | - | - |
|
Unscheduled
|
2016-06-07 | 2016-06-27 | 21 | 36d | - | - |
|
Unscheduled
|
2016-04-23 | 2016-05-02 | 10 | 3d | - | - |
|
Scheduled
|
2016-03-13 | 2016-04-20 | 39 | 116d | 2016-03-13 | 0d |
|
Scram
# 51532
|
2015-11-13 | 2015-11-18 | 6 | 331d | - | - |
|
Unscheduled
|
2014-12-14 | 2014-12-17 | 4 | 193d | - | - |
|
Scheduled
|
2014-04-13 | 2014-06-04 | 53 | 306d | 2014-04-12 | +1d |
|
Unscheduled
|
2013-06-11 | 2013-06-11 | 1 | 3d | - | - |
|
Scram
# 49099
|
2013-06-08 | 2013-06-08 | 1 | 2d | - | - |
|
Scram
# 49099
|
2013-06-05 | 2013-06-06 | 2 | 4d | - | - |
|
Unscheduled
|
2013-05-09 | 2013-06-01 | 24 | 184d | - | - |
|
Unscheduled
|
2012-10-21 | 2012-11-06 | 17 | 113d | - | - |
|
Unscheduled
|
2012-06-20 | 2012-06-30 | 11 | 16d | - | - |
|
Scheduled
|
2012-04-01 | 2012-06-04 | 65 | 284d | 2012-03-30 | +2d |
|
Unscheduled
|
2011-05-17 | 2011-06-22 | 37 | 69d | - | - |
|
Unscheduled
|
2011-03-05 | 2011-03-09 | 5 | 37d | - | - |
|
Scram
# 46569
|
2011-01-26 | 2011-01-27 | 2 | 176d | - | - |
|
Unscheduled
|
2010-07-17 | 2010-08-03 | 18 | 61d | - | - |
|
Unscheduled
|
2010-05-15 | 2010-05-17 | 3 | 21d | - | - |
|
Unscheduled
|
2010-04-23 | 2010-04-24 | 2 | 7d | - | - |
|
Scheduled
|
2010-03-02 | 2010-04-16 | 46 | 685d | 2010-03-02 | 0d |
|
Scheduled
|
2008-03-04 | 2008-04-16 | 44 | 128d | 2008-03-05 | -1d |
|
Unscheduled
|
2007-10-13 | 2007-10-28 | 16 | 319d | - | - |
|
Unscheduled
|
2006-11-26 | 2006-11-28 | 3 | 161d | - | - |
|
Unscheduled
|
2006-06-15 | 2006-06-18 | 4 | 66d | - | - |
|
Scheduled
|
2006-03-04 | 2006-04-10 | 38 | 110d | 2006-03-03 | +1d |
|
Unscheduled
|
2005-10-29 | 2005-11-14 | 17 | 555d | - | - |
|
Unscheduled
|
2004-04-22 | 2004-04-22 | 1 | 2d | - | - |
|
Scheduled
|
2004-02-28 | 2004-04-20 | 53 | 153d | 2004-02-27 | +1d |
|
Unscheduled
|
2003-09-24 | 2003-09-28 | 5 | 519d | - | - |
|
Scheduled
|
2002-03-02 | 2002-04-23 | 53 | 667d | 2002-03-02 | 0d |
|
Scheduled
|
2000-03-19 | 2000-05-04 | 47 | 249d | 2000-03-19 | 0d |
|
Unscheduled
|
1999-07-01 | 1999-07-14 | 14 | 27d | - | - |
|
Unscheduled
|
1999-05-30 | 1999-06-04 | 6 | - | - | - |
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