Ginna - 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.
69
Excellence
#22 of 94 →
Top Quartile
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
21
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2005-04-10 to 2006-10-09).
547
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (466 days for this 18-month cycle unit) with no trips to 0% power.
9
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
93.6%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
19
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.
98.1%
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
69/100
Top Quartile · #22/94
5-year window

Ginna ranks #22 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Refuel Duration (93th percentile). Weakest: Startup Duration (48th percentile).

Reliability
68
Capacity factor + Forced outages + B2B streaks
Efficiency
90
Fuel utilization + Refuel duration
Discipline
48
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #13 of 61 PWR
Containment: #11 of 48 Dry Ambient (PWR)
Cycle length: #10 of 54 18-month cycle
Fleet rank above (22 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 75th
94.1% (higher better, Reliability)
Forced Outage Days/yr 78th
1.6d (lower better, Reliability)
B2B Avg Streak 49th
515d (higher better, Reliability)
Fuel Utilization 87th
98.9% (higher better, Efficiency)
Refuel Duration 93th
18d (lower better, Efficiency)
Startup Duration 48th
4.5d (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: 80/100 (#8/93)2022: 83/100 (#9/92)2023: 67/100 (#22/92)2024: 67/100 (#18/93)2025: 70/100 (#22/94)2026: 70/100 (#21/94) Stable vs 2025
Compare Ginna 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 24, 2026

96.5% remaining 19 / 532 days 0.6 FPD margin
Avg refuel: 3.7% Avg refuel (3yr): 1.9% Deepest burn: 0.0% (2005-04 → 2006-10) Most margin: 9.5% (2008-05 → 2009-09)
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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
2026-04-06 2026-04-23 18 538d 2026-04-06 0d
Scheduled
2024-09-30 2024-10-15 16 352d 2024-09-30 0d
Scram # 56790
2023-10-13 2023-10-14 2 32d - -
Scram # 56731
2023-09-10 2023-09-11 2 133d - -
Scheduled
2023-04-10 2023-04-30 21 535d 2023-04-09 +1d
Scheduled
2021-10-04 2021-10-22 19 499d 2021-10-18 -14d
Scheduled
2020-04-06 2020-05-23 48 294d 2020-04-06 0d
Unscheduled
2019-06-17 2019-06-17 1 221d - -
Scheduled
2018-10-22 2018-11-08 18 226d 2018-10-22 0d
Unscheduled
2018-03-09 2018-03-10 2 299d - -
Scheduled
2017-04-24 2017-05-14 21 535d 2017-04-24 0d
Scheduled
2015-10-19 2015-11-06 19 512d 2015-10-19 0d
Unscheduled Startup Hold
2014-05-25 2014-05-25 1 5d - -
Scheduled
2014-04-28 2014-05-20 23 275d 2014-04-27 +1d
Scram # 49214
2013-07-25 2013-07-27 3 247d - -
Unscheduled Startup Hold
2012-11-20 2012-11-20 1 2d - -
Scheduled
2012-10-22 2012-11-18 28 373d 2012-10-20 +2d
Scram # 47338
2011-10-12 2011-10-15 4 125d - -
Scheduled
2011-04-24 2011-06-09 47 475d 2011-04-25 -1d
Unscheduled
2009-12-31 2010-01-04 5 90d - -
Scheduled
2009-09-14 2009-10-02 19 491d 2009-09-13 +1d
Scheduled
2008-04-21 2008-05-11 21 400d 2008-04-13 +8d
Unscheduled
2007-03-17 2007-03-18 2 48d - -
Unscheduled
2007-01-28 2007-01-28 1 87d - -
Scheduled
2006-10-09 2006-11-02 25 547d 2006-10-08 +1d
Scheduled
2005-03-21 2005-04-10 21 31d 2005-03-20 +1d
Unscheduled
2005-02-17 2005-02-18 2 123d - -
Unscheduled
2004-10-16 2004-10-17 2 368d - -
Scheduled
2003-09-16 2003-10-14 29 30d 2003-09-16 0d
Unscheduled
2003-08-15 2003-08-17 3 484d - -
Scheduled
2002-03-19 2002-04-18 31 41d 2002-03-19 0d
Unscheduled
2002-02-06 2002-02-06 1 472d - -
Unscheduled
2000-10-22 2000-10-22 1 4d - -
Scheduled
2000-09-19 2000-10-18 30 509d 2000-09-19 0d
Unscheduled
1999-04-28 1999-04-29 2 7d - -
Scheduled
1999-03-02 1999-04-21 51 - 1999-03-02 0d
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