Davis-Besse - 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.
66
Excellence
#24 of 94 ↑32
Top Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
45
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2000-05-18 to 2002-02-16).
639
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (567 days for this 24-month cycle unit) with no trips to 0% power.
1
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
83.4%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
13
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
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.
98.9%
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
66/100
Top Quartile · #24/94
5-year window

Davis-Besse ranks #24 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Startup Duration (97th percentile). Weakest: Forced Outage Days/yr (39th percentile).

Reliability
52
Capacity factor + Forced outages + B2B streaks
Efficiency
62
Fuel utilization + Refuel duration
Discipline
84
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #14 of 61 PWR
Containment: #12 of 48 Dry Ambient (PWR)
Cycle length: #14 of 40 24-month cycle
Fleet rank above (24 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 52th
91.1% (higher better, Reliability)
Forced Outage Days/yr 39th
5.0d (lower better, Reliability)
B2B Avg Streak 66th
638d (higher better, Reliability)
Fuel Utilization 60th
98.2% (higher better, Efficiency)
Refuel Duration 63th
29d (lower better, Efficiency)
Startup Duration 97th
2.7d (lower better, Discipline)
Scrams (5-year) 70th
0.2/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: 55/100 (#45/93)2022: 50/100 (#49/92)2023: 31/100 (#75/92)2024: 60/100 (#26/93)2025: 45/100 (#58/94)2026: 61/100 (#26/94) ↑ +16.3 pts vs 2025
Compare Davis-Besse 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 Mar 31, 2026

93.9% remaining 43 / 701 days 0.4 FPD margin
Avg refuel: 6.9% Avg refuel (3yr): 1.1% Deepest burn: 0.0% (2008-02 → 2010-02) Most margin: 17.1% (2012-06 → 2014-02)
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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
Scheduled
2026-03-01 2026-03-30 30 195d 2026-02-28 +1d
Unscheduled
2025-08-13 2025-08-18 6 503d - -
Scheduled
2024-03-03 2024-03-28 26 442d 2024-03-01 +2d
Unscheduled
2022-12-05 2022-12-17 13 231d - -
Scheduled
2022-03-05 2022-04-18 45 237d 2022-03-05 0d
Scram # 55346
2021-07-09 2021-07-11 3 470d - -
Scheduled
2020-02-29 2020-03-26 27 172d 2020-02-29 0d
Scram # 54263
2019-09-08 2019-09-10 3 237d - -
Unscheduled
2019-01-13 2019-01-14 2 293d - -
Scheduled
2018-03-03 2018-03-26 24 529d 2018-03-03 0d
Scram # 52232
2016-09-10 2016-09-20 11 124d - -
Scheduled
2016-03-26 2016-05-09 45 55d 2016-03-26 0d
Scram # 51696
2016-01-30 2016-01-31 2 264d - -
Scram # 51061
2015-05-10 2015-05-11 2 369d - -
Scheduled SGR/Major
2014-02-01 2014-05-06 95 205d 2014-02-06 -5d
Scram # 49159
2013-06-30 2013-07-11 12 383d - -
Scheduled
2012-05-06 2012-06-12 38 153d 2012-05-01 +5d
Unscheduled
2011-10-01 2011-12-05 66 261d - -
Unscheduled
2011-01-09 2011-01-13 5 195d - -
Scheduled SGR/Major
2010-02-28 2010-06-28 121 314d 2010-02-28 0d
Unscheduled
2009-04-05 2009-04-20 16 417d - -
Unscheduled
2008-02-06 2008-02-13 8 6d - -
Scheduled
2007-12-30 2008-01-31 33 401d 2007-12-28 +2d
Unscheduled
2006-11-18 2006-11-24 7 72d - -
Unscheduled
2006-09-06 2006-09-07 2 133d - -
Scheduled
2006-03-06 2006-04-26 52 127d 2006-03-05 +1d
Unscheduled
2005-10-29 2005-10-30 2 262d - -
Unscheduled
2005-01-18 2005-02-09 23 164d - -
Unscheduled
2004-08-05 2004-08-07 3 132d - -
Scheduled
2004-03-18 2004-03-26 9 4d 2004-02-16 (Enhanced) +31d (Enhanced)
Scheduled Ext. Shutdown
2002-02-16 2004-03-14 758 639d 2002-02-16 0d
Scheduled
2000-04-01 2000-05-18 48 327d 2000-04-01 0d
Unscheduled
1999-04-24 1999-05-10 17 - - -
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