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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.
26
Excellence
#85 of 94 ↓16
Bottom 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 (2019-05-13 to 2021-04-18).
706
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (616 days for this 24-month cycle unit) with no trips to 0% power.
3
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.
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.
95.7%
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
26/100
Bottom Quartile · #85/94
5-year window
Monticello ranks #85 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: B2B Avg Streak (74th percentile). Weakest: Forced Outage Days/yr (8th percentile).
Reliability
33
Capacity factor + Forced outages + B2B streaks
Efficiency
25
Fuel utilization + Refuel duration
Discipline
20
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#26 of 31
BWR
Containment:
#17 of 19
Mark I (BWR)
Cycle length:
#35 of 40
24-month cycle
Fleet rank above (85 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
17th
86.1% (higher better, Reliability)
Forced Outage Days/yr
8th
17.6d (lower better, Reliability)
B2B Avg Streak
74th
681d (higher better, Reliability)
Fuel Utilization
15th
95.4% (higher better, Efficiency)
Refuel Duration
35th
35d (lower better, Efficiency)
Startup Duration
24th
6.0d (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:
↓ -12.3 pts vs 2025
Compare Monticello 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 27, 2025
59.1% remaining
351 / 704 days
62.7 FPD margin
Avg refuel: 11.0%
Avg refuel (3yr): 4.3%
Deepest burn: 2.7% (2019-05 → 2021-04)
Most margin: 31.0% (2001-12 → 2003-04)
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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 |
|---|---|---|---|---|---|---|
| 2026-02-21 | 2026-04-02 | 41 | 188d | - | - | |
|
Unscheduled
|
2025-08-14 | 2025-08-17 | 4 | 13d | - | - |
|
Scram
# 57832
|
2025-07-29 | 2025-08-01 | 4 | 56d | - | - |
|
Unscheduled
|
2025-06-02 | 2025-06-03 | 2 | 9d | - | - |
|
Scheduled
|
2025-04-19 | 2025-05-24 | 36 | 28d | 2025-04-12 | +7d |
|
Scram
# 57618
|
2025-03-20 | 2025-03-22 | 3 | 354d | - | - |
|
Unscheduled
|
2024-03-27 | 2024-03-31 | 5 | 25d | - | - |
|
Scram
# 56995
|
2024-02-29 | 2024-03-02 | 3 | 146d | - | - |
|
Scram
# 56759
|
2023-09-28 | 2023-10-06 | 9 | 138d | - | - |
|
Scheduled
|
2023-04-15 | 2023-05-13 | 29 | 16d | 2023-04-15 | 0d |
|
Unscheduled
|
2023-03-26 | 2023-03-30 | 5 | 423d | - | - |
|
Unscheduled
|
2022-01-25 | 2022-01-27 | 3 | 251d | - | - |
|
Scheduled
|
2021-04-18 | 2021-05-19 | 32 | 706d | 2021-04-17 | +1d |
|
Scheduled
|
2019-04-14 | 2019-05-13 | 30 | 700d | 2019-04-13 | +1d |
|
Scheduled
|
2017-04-15 | 2017-05-14 | 30 | 503d | 2017-04-15 | 0d |
|
Scram
# 51560
|
2015-11-24 | 2015-11-29 | 6 | 180d | - | - |
|
Scheduled
|
2015-04-13 | 2015-05-28 | 46 | 432d | 2015-04-11 | +2d |
|
Unscheduled
|
2014-01-19 | 2014-02-05 | 18 | 185d | - | - |
|
Scheduled
SGR/Major
|
2013-03-02 | 2013-07-18 | 139 | 156d | 2013-03-02 | 0d |
|
Scram
# 48341
|
2012-09-26 | 2012-09-27 | 2 | 40d | - | - |
|
Unscheduled
|
2012-08-15 | 2012-08-17 | 3 | 251d | - | - |
|
Unscheduled
|
2011-11-29 | 2011-12-08 | 10 | 2d | - | - |
|
Scram
# 47460
|
2011-11-20 | 2011-11-27 | 8 | 24d | - | - |
|
Scram
# 47364
|
2011-10-22 | 2011-10-27 | 6 | 117d | - | - |
|
Unscheduled
|
2011-06-25 | 2011-06-27 | 3 | 34d | - | - |
|
Scheduled
SGR/Major
|
2011-03-05 | 2011-05-22 | 79 | 102d | 2011-03-05 | 0d |
|
Unscheduled
|
2010-11-18 | 2010-11-23 | 6 | 561d | - | - |
|
Scheduled
|
2009-03-15 | 2009-05-06 | 53 | 170d | 2009-03-16 | -1d |
|
Unscheduled
|
2008-09-12 | 2008-09-26 | 15 | 505d | - | - |
|
Scheduled
|
2007-03-14 | 2007-04-26 | 44 | 50d | 2007-03-13 | +1d |
|
Unscheduled
|
2007-01-11 | 2007-01-23 | 13 | 641d | - | - |
|
Scheduled
|
2005-03-06 | 2005-04-10 | 36 | 258d | 2005-03-05 | +1d |
|
Unscheduled
|
2004-06-19 | 2004-06-21 | 3 | 369d | - | - |
|
Unscheduled
|
2003-06-15 | 2003-06-16 | 2 | 21d | - | - |
|
Scheduled
|
2003-04-27 | 2003-05-25 | 29 | 457d | 2003-04-27 | 0d |
|
Unscheduled
|
2002-01-22 | 2002-01-25 | 4 | 40d | - | - |
|
Scheduled
|
2001-11-04 | 2001-12-13 | 40 | 10d | 2001-11-04 | 0d |
|
Unscheduled
|
2001-10-24 | 2001-10-25 | 2 | 204d | - | - |
|
Unscheduled
|
2001-02-26 | 2001-04-03 | 37 | 178d | - | - |
|
Unscheduled
|
2000-08-28 | 2000-09-01 | 5 | 183d | - | - |
|
Scheduled
|
2000-01-06 | 2000-02-27 | 53 | 224d | 2000-01-06 | 0d |
|
Unscheduled
|
1999-05-09 | 1999-05-27 | 19 | 10d | - | - |
|
Unscheduled
|
1999-04-22 | 1999-04-29 | 8 | - | - | - |
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