D.C. Cook 1 - Status & History

Comprehensive reactor performance metrics, cycle analysis, and historical outage data.

Plant Info Outage History Daily Power Log
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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.
36
Excellence
#70 of 94 ↑4
Mid Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
380
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2011-10-25 to 2013-03-27).
519
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (452 days for this 18-month cycle unit) with no trips to 0% power.
6
B2B Runs
82% toward B2B (372/452d)
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
78.2%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
16
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.
6.3
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.
97.1%
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.
Time window — change how far back we look
NukeWorker's
Operational
Excellence Score
36/100
Mid Quartile · #70/94
5-year window

D.C. Cook 1 ranks #70 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Capacity Factor (66th percentile). Weakest: B2B Avg Streak (11th percentile).

Reliability
41
Capacity factor + Forced outages + B2B streaks
Efficiency
28
Fuel utilization + Refuel duration
Discipline
38
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #49 of 61 PWR
Containment: #6 of 10 Ice Condenser
Cycle length: #41 of 54 18-month cycle
Fleet rank above (70 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 66th
92.9% (higher better, Reliability)
Forced Outage Days/yr 46th
4.0d (lower better, Reliability)
B2B Avg Streak 11th
495d (higher better, Reliability)
Fuel Utilization 34th
97.3% (higher better, Efficiency)
Refuel Duration 23th
38d (lower better, Efficiency)
Startup Duration 29th
5.7d (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: 2021: 44/100 (#58/93)2022: 28/100 (#75/92)2023: 27/100 (#81/92)2024: 43/100 (#60/93)2025: 35/100 (#72/94)2026: 37/100 (#68/94) ↑ +2.1 pts vs 2025
Compare D.C. Cook 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 1, 2025

24.9% remaining 377 / 501 days 0.6 FPD margin
Avg refuel: 7.5% Avg refuel (3yr): 2.9% Deepest burn: 0.0% (2010-04 → 2011-09) Most margin: 57.6% (2008-04 → 2010-03)
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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
2025-03-22 2025-04-29 39 495d 2025-04-12 -21d
Scheduled
2023-10-14 2023-11-13 31 405d 2023-10-14 0d
Scram # 56076
2022-08-29 2022-09-04 7 92d - -
Scram # 55910
2022-05-25 2022-05-29 5 3d - -
Scheduled
2022-04-02 2022-05-22 51 244d 2022-04-02 0d
Unscheduled
2021-07-28 2021-08-01 5 283d - -
Scheduled
2020-09-19 2020-10-18 30 499d 2020-09-22 -3d
Scheduled
2019-03-06 2019-05-09 65 464d 2019-03-06 0d
Scheduled SGR/Major
2017-09-13 2017-11-27 76 504d 2017-09-20 -7d
Scheduled
2016-03-23 2016-04-27 36 238d 2016-03-22 +1d
Unscheduled
2015-06-01 2015-07-29 59 210d - -
Scram # 50587
2014-11-01 2014-11-03 3 9d - -
Scram # 50587
2014-11-01 2014-11-03 3 2d - -
Scheduled
2014-09-24 2014-10-23 30 494d 2014-09-24 0d
Scheduled
2013-03-27 2013-05-18 53 519d 2013-03-13 +14d
Scheduled
2011-09-21 2011-10-25 35 12d 2011-09-21 0d
Scram # 47247
2011-09-08 2011-09-09 2 175d - -
Unscheduled
2011-03-12 2011-03-17 6 337d - -
Scheduled
2010-03-03 2010-04-09 38 76d 2010-03-03 0d
Unscheduled
2008-09-21 2009-12-17 453 145d - -
Scheduled
2008-03-26 2008-04-29 35 52d 2008-03-15 +11d
Unscheduled
2008-02-03 2008-02-03 1 158d - -
Unscheduled
2007-08-29 2007-08-29 1 292d - -
Scheduled
2006-09-16 2006-11-10 56 45d 2006-09-15 +1d
Unscheduled
2006-07-31 2006-08-02 3 461d - -
Scheduled
2005-03-26 2005-04-26 32 354d 2005-03-26 0d
Unscheduled
2004-03-31 2004-04-06 7 127d - -
Scheduled
2003-10-18 2003-11-25 39 144d 2003-10-18 0d
Unscheduled
2003-04-24 2003-05-27 34 79d - -
Unscheduled
2003-01-16 2003-02-04 20 213d - -
Unscheduled
2002-06-15 2002-06-17 3 7d - -
Scheduled
2002-05-04 2002-06-08 36 217d 2002-05-04 0d
Unscheduled
2001-08-28 2001-09-29 33 191d - -
Unscheduled
2001-02-16 2001-02-18 3 58d - -
Unscheduled
1999-01-01 2000-12-20 720 - - -
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