?
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.
28
Excellence
#81 of 94 →
Bottom Quartile
?
Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
166
Current Run
days ✔
?
Longest recorded period of continuous operation between outages (2007-05-08 to 2008-10-11).
522
Record Run
days
?
Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (400 days for this 18-month cycle unit) with no trips to 0% power.
8
B2B Runs
?
Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
85.6%
Capacity Factor
?
Total number of scheduled refueling outages detected in the historical data.
18
Outages
since 1999
?
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.
3.3
Avg Startup
days (last 3)
?
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
?
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
28/100
Bottom Quartile · #81/94
5-year window
Callaway ranks #81 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Startup Duration (69th percentile). Weakest: B2B Avg Streak (2th percentile).
Reliability
5
Capacity factor + Forced outages + B2B streaks
Efficiency
22
Fuel utilization + Refuel duration
Discipline
58
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#56 of 61
PWR
Containment:
#45 of 48
Dry Ambient (PWR)
Cycle length:
#48 of 54
18-month cycle
Fleet rank above (81 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
8th
79.1% (higher better, Reliability)
Forced Outage Days/yr
5th
24.0d (lower better, Reliability)
B2B Avg Streak
2th
467d (higher better, Reliability)
Fuel Utilization
38th
97.5% (higher better, Efficiency)
Refuel Duration
6th
54d (lower better, Efficiency)
Startup Duration
69th
3.7d (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:
Stable vs 2025
Compare Callaway head-to-head with up to 3 other units.
Compare now
?
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
?
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
?
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
?
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 Jul 8, 2025
40.6% remaining
309 / 487 days
19.7 FPD margin
Avg refuel: 4.7%
Avg refuel (3yr): 0.0%
Deepest burn: 0.0% (1999-11 → 2001-04)
Most margin: 51.4% (2020-12 → 2022-04)
?
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 |
|---|---|---|---|---|---|---|
|
Unscheduled
|
2025-11-13 | 2025-11-29 | 17 | 131d | - | - |
|
Scheduled
SGR/Major
|
2025-03-29 | 2025-07-05 | 99 | 405d | 2025-04-11 | -13d |
|
Scram
# 56968
|
2024-02-15 | 2024-02-18 | 4 | 101d | - | - |
|
Scheduled
|
2023-09-30 | 2023-11-06 | 38 | 145d | 2023-09-30 | 0d |
|
Unscheduled
|
2023-04-28 | 2023-05-08 | 11 | 335d | - | - |
|
Scheduled
|
2022-04-04 | 2022-05-28 | 55 | 84d | 2022-04-04 | 0d |
|
Scram
# 55698
|
2022-01-08 | 2022-01-10 | 3 | 159d | - | - |
|
Scram
# 55049
|
2020-12-25 | 2021-08-02 | 221 | 5d | - | - |
|
Scheduled
|
2020-09-27 | 2020-12-20 | 85 | 174d | 2020-10-03 | -6d |
|
Scram
# 54639
|
2020-04-04 | 2020-04-06 | 3 | 323d | - | - |
|
Scheduled
|
2019-04-01 | 2019-05-17 | 47 | 470d | 2019-04-01 | 0d |
|
Scheduled
|
2017-10-07 | 2017-12-17 | 72 | 516d | 2017-10-06 | +1d |
|
Scheduled
|
2016-04-03 | 2016-05-09 | 37 | 235d | 2016-04-08 | -5d |
|
Scram
# 51308
|
2015-08-11 | 2015-08-12 | 2 | 17d | - | - |
|
Unscheduled
|
2015-07-24 | 2015-07-25 | 2 | 231d | - | - |
|
Scram
# 50650
|
2014-12-03 | 2014-12-05 | 3 | 12d | - | - |
|
Scheduled
|
2014-10-12 | 2014-11-21 | 41 | 422d | 2014-10-04 | +8d |
|
Scram
# 49219
|
2013-07-27 | 2013-08-16 | 21 | 61d | - | - |
|
Scheduled
|
2013-04-09 | 2013-05-27 | 49 | 502d | 2013-04-06 | +3d |
|
Scheduled
|
2011-10-16 | 2011-11-24 | 40 | 492d | 2011-10-15 | +1d |
|
Scheduled
|
2010-04-18 | 2010-06-11 | 55 | 413d | 2010-04-17 | +1d |
|
Unscheduled
|
2009-02-22 | 2009-03-01 | 8 | 2d | - | - |
|
Unscheduled
|
2009-02-20 | 2009-02-20 | 1 | 60d | - | - |
|
Unscheduled
|
2008-12-15 | 2008-12-22 | 8 | 2d | - | - |
|
Unscheduled
|
2008-12-12 | 2008-12-13 | 2 | 30d | - | - |
|
Unscheduled
|
2008-11-12 | 2008-11-12 | 1 | 6d | - | - |
|
Scheduled
|
2008-10-11 | 2008-11-06 | 27 | 522d | 2008-10-11 | 0d |
|
Scheduled
|
2007-04-02 | 2007-05-08 | 37 | 21d | 2007-04-01 | +1d |
|
Unscheduled
|
2007-03-10 | 2007-03-12 | 3 | 281d | - | - |
|
Unscheduled
|
2006-05-18 | 2006-06-02 | 16 | 6d | - | - |
|
Unscheduled
|
2006-05-12 | 2006-05-12 | 1 | 176d | - | - |
|
Scheduled
|
2005-09-17 | 2005-11-17 | 62 | 91d | 2005-09-16 | +1d |
|
Unscheduled
|
2005-06-17 | 2005-06-18 | 2 | 77d | - | - |
|
Unscheduled
|
2005-03-27 | 2005-04-01 | 6 | 66d | - | - |
|
Unscheduled
|
2005-01-20 | 2005-01-20 | 1 | 223d | - | - |
|
Scheduled
|
2004-04-11 | 2004-06-11 | 62 | 54d | 2004-04-10 | +1d |
|
Unscheduled
|
2004-02-16 | 2004-02-17 | 2 | 2d | - | - |
|
Unscheduled
|
2004-02-04 | 2004-02-14 | 11 | 7d | - | - |
|
Unscheduled
|
2004-01-28 | 2004-01-28 | 1 | 96d | - | - |
|
Unscheduled
|
2003-10-22 | 2003-10-24 | 3 | 203d | - | - |
|
Unscheduled
|
2003-03-23 | 2003-04-02 | 11 | 96d | - | - |
|
Unscheduled
|
2002-12-15 | 2002-12-17 | 3 | 20d | - | - |
|
Scheduled
|
2002-10-23 | 2002-11-25 | 34 | 250d | 2002-10-23 | 0d |
|
Unscheduled
|
2002-02-01 | 2002-02-15 | 15 | 57d | - | - |
|
Unscheduled
|
2001-12-04 | 2001-12-06 | 3 | 197d | - | - |
|
Scheduled
|
2001-04-07 | 2001-05-21 | 45 | 27d | 2001-04-07 | 0d |
|
Unscheduled
|
2001-03-10 | 2001-03-11 | 2 | 469d | - | - |
|
Unscheduled
|
1999-11-27 | 1999-11-27 | 1 | 23d | - | - |
|
Scheduled
|
1999-10-02 | 1999-11-04 | 34 | 46d | 1999-10-02 | 0d |
|
Unscheduled
|
1999-08-12 | 1999-08-17 | 6 | - | - | - |
Page created in 0.093 seconds with 7 queries.