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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.
46
Excellence
#55 of 94 ↑5
Mid Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
343
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2023-03-21 to 2025-03-05).
715
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.
2
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
90.3%
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.
8.7
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.
100.0%
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
46/100
Mid Quartile · #55/94
5-year window
Browns Ferry 2 ranks #55 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: B2B Avg Streak (77th percentile). Weakest: Startup Duration (12th percentile).
Reliability
68
Capacity factor + Forced outages + B2B streaks
Efficiency
41
Fuel utilization + Refuel duration
Discipline
30
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#16 of 31
BWR
Containment:
#11 of 19
Mark I (BWR)
Cycle length:
#24 of 40
24-month cycle
Fleet rank above (55 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
60th
92.4% (higher better, Reliability)
Forced Outage Days/yr
66th
2.4d (lower better, Reliability)
B2B Avg Streak
77th
691d (higher better, Reliability)
Fuel Utilization
53th
98.1% (higher better, Efficiency)
Refuel Duration
29th
36d (lower better, Efficiency)
Startup Duration
12th
7.9d (lower better, Discipline)
Scrams (5-year)
48th
0.4/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:
↑ +2.1 pts vs 2025
Compare Browns Ferry 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 Apr 12, 2025
44.9% remaining
396 / 688 days
17.0 FPD margin
Avg refuel: 5.1%
Avg refuel (3yr): 0.0%
Deepest burn: 0.0% (2003-03 → 2005-03)
Most margin: 16.7% (2009-06 → 2011-02)
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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
# 57737
|
2025-05-31 | 2025-06-05 | 6 | 15d | - | - |
|
Scram
# 57705
|
2025-05-13 | 2025-05-16 | 4 | 33d | - | - |
|
Scheduled
|
2025-03-05 | 2025-04-10 | 37 | 715d | 2025-02-28 | +5d |
|
Scheduled
|
2023-02-18 | 2023-03-21 | 32 | 668d | 2023-02-17 | +1d |
|
Scheduled
|
2021-02-27 | 2021-04-21 | 54 | 215d | 2021-02-27 | 0d |
|
Scram
# 54794
|
2020-07-21 | 2020-07-27 | 7 | 40d | - | - |
|
Unscheduled
|
2020-06-06 | 2020-06-11 | 6 | 15d | - | - |
|
Unscheduled
|
2020-05-20 | 2020-05-22 | 3 | 226d | - | - |
|
Unscheduled
|
2019-09-21 | 2019-10-07 | 17 | 165d | - | - |
|
Scheduled
|
2019-03-02 | 2019-04-09 | 39 | 296d | 2019-03-02 | 0d |
|
Unscheduled
|
2018-05-07 | 2018-05-10 | 4 | 403d | - | - |
|
Scheduled
|
2017-02-25 | 2017-03-30 | 34 | 440d | 2017-02-25 | 0d |
|
Unscheduled
|
2015-12-07 | 2015-12-13 | 7 | 242d | - | - |
|
Scheduled
|
2015-03-14 | 2015-04-09 | 27 | 220d | 2015-03-14 | 0d |
|
Unscheduled
|
2014-08-04 | 2014-08-06 | 3 | 457d | - | - |
|
Scheduled
|
2013-03-15 | 2013-05-04 | 51 | 80d | 2013-03-16 | -1d |
|
Scram
# 48623
|
2012-12-23 | 2012-12-25 | 3 | 580d | - | - |
|
Scram
# 46793
|
2011-04-28 | 2011-05-23 | 26 | 23d | - | - |
|
Scram
# 46793
|
2011-04-28 | 2011-05-23 | 26 | 25d | - | - |
|
Scram
# 46793
|
2011-04-28 | 2011-05-23 | 26 | 25d | - | - |
|
Scheduled
|
2011-02-26 | 2011-04-05 | 39 | 260d | 2011-02-28 | -2d |
|
Unscheduled
|
2010-06-10 | 2010-06-11 | 2 | 146d | - | - |
|
Unscheduled
|
2010-01-11 | 2010-01-15 | 5 | 100d | - | - |
|
Unscheduled
|
2009-09-30 | 2009-10-03 | 4 | 102d | - | - |
|
Unscheduled
|
2009-06-17 | 2009-06-20 | 4 | 2d | - | - |
|
Unscheduled
|
2009-06-12 | 2009-06-15 | 4 | 4d | - | - |
|
Scheduled
|
2009-04-26 | 2009-06-08 | 44 | 64d | 2009-04-27 | -1d |
|
Unscheduled
|
2009-02-17 | 2009-02-21 | 5 | 133d | - | - |
|
Unscheduled
|
2008-10-05 | 2008-10-07 | 3 | 14d | - | - |
|
Unscheduled
|
2008-09-18 | 2008-09-21 | 4 | 395d | - | - |
|
Unscheduled
|
2007-08-17 | 2007-08-20 | 4 | 123d | - | - |
|
Scheduled
|
2007-02-21 | 2007-04-16 | 55 | 40d | 2007-02-20 | +1d |
|
Unscheduled
|
2007-01-12 | 2007-01-12 | 1 | 83d | - | - |
|
Unscheduled
|
2006-10-11 | 2006-10-21 | 11 | 140d | - | - |
|
Unscheduled
|
2006-05-21 | 2006-05-24 | 4 | 288d | - | - |
|
Unscheduled
|
2005-08-06 | 2005-08-06 | 1 | 112d | - | - |
|
Scheduled
|
2005-03-22 | 2005-04-16 | 26 | 254d | 2005-03-21 | +1d |
|
Unscheduled
|
2004-07-09 | 2004-07-11 | 3 | 245d | - | - |
|
Unscheduled
|
2003-10-29 | 2003-11-07 | 10 | 216d | - | - |
|
Unscheduled
Startup Hold
|
2003-03-26 | 2003-03-27 | 2 | 2d | - | - |
|
Unscheduled
Startup Hold
|
2003-03-20 | 2003-03-24 | 5 | 5d | - | - |
|
Scheduled
|
2003-02-25 | 2003-03-15 | 19 | 120d | 2003-02-25 | 0d |
|
Unscheduled
|
2002-10-20 | 2002-10-28 | 9 | 83d | - | - |
|
Unscheduled
|
2002-07-28 | 2002-07-29 | 2 | 89d | - | - |
|
Unscheduled
|
2002-04-23 | 2002-04-30 | 8 | 136d | - | - |
|
Unscheduled
|
2001-12-06 | 2001-12-08 | 3 | 133d | - | - |
|
Unscheduled
|
2001-07-26 | 2001-07-26 | 1 | 94d | - | - |
|
Scheduled
|
2001-03-19 | 2001-04-23 | 36 | 261d | 2001-03-19 | 0d |
|
Unscheduled
|
2000-06-30 | 2000-07-01 | 2 | 286d | - | - |
|
Unscheduled
|
1999-09-18 | 1999-09-18 | 1 | 2d | - | - |
|
Unscheduled
|
1999-09-16 | 1999-09-16 | 1 | 123d | - | - |
|
Unscheduled
|
1999-05-16 | 1999-05-16 | 1 | 10d | - | - |
|
Scheduled
|
1999-04-12 | 1999-05-06 | 25 | - | 1999-04-12 | 0d |
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