Oconee 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.
91
Excellence
#1 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).
548
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2020-11-17 to 2022-10-29).
711
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (613 days for this 24-month cycle unit) with no trips to 0% power.
3
B2B Runs
88% toward B2B (540/613d)
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
90.8%
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.
1.3
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.
77.7%
Fuel Utilization
lifetime 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
91/100
Top Quartile · #1/94
5-year window

Oconee 1 ranks #1 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Capacity Factor (100th percentile). Weakest: Refuel Duration (72th percentile).

Reliability
93
Capacity factor + Forced outages + B2B streaks
Efficiency
86
Fuel utilization + Refuel duration
Discipline
95
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #1 of 61 PWR
Containment: #1 of 48 Dry Ambient (PWR)
Cycle length: #1 of 40 24-month cycle
Fleet rank above (1 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 100th
97.7% (higher better, Reliability)
Forced Outage Days/yr 98th
0.4d (lower better, Reliability)
B2B Avg Streak 81th
695d (higher better, Reliability)
Fuel Utilization 100th
99.8% (higher better, Efficiency)
Refuel Duration 72th
26d (lower better, Efficiency)
Startup Duration 100th
2.0d (lower better, Discipline)
Scrams (5-year) 90th
0.0/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: 53/100 (#50/93)2022: 65/100 (#25/92)2023: 77/100 (#14/92)2024: 84/100 (#9/93)2025: 85/100 (#9/94)2026: 85/100 (#6/94) Stable vs 2025
Compare Oconee 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 Nov 13, 2024

22.1% remaining 546 / 701 days 0.0 FPD margin
Avg refuel: 22.3% Deepest burn: 0.0% (2016-03 → 2018-10) Most margin: 40.1% (2001-01 → 2002-03)
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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
2024-10-22 2024-11-12 22 698d 2024-10-19 +3d
Scheduled
2022-10-29 2022-11-24 27 711d 2022-10-29 0d
Scheduled
2020-10-17 2020-11-17 32 679d 2020-10-24 -7d
Unscheduled
2018-12-01 2018-12-08 8 17d - -
Scheduled
2018-10-20 2018-11-14 26 189d 2018-10-13 +7d
Scram # 53329
2018-04-13 2018-04-14 2 413d - -
Unscheduled
2017-02-18 2017-02-24 7 84d - -
Unscheduled
2016-11-05 2016-11-26 22 222d - -
Scheduled
2016-03-07 2016-03-28 22 456d 2016-03-07 0d
Scheduled
2014-11-04 2014-12-07 34 338d 2014-11-01 +3d
Unscheduled
2013-11-12 2013-12-01 20 348d - -
Scheduled
2012-10-27 2012-11-29 34 101d 2012-10-27 0d
Unscheduled
2012-07-18 2012-07-18 1 405d - -
Scheduled
2011-04-02 2011-06-09 69 76d 2011-04-02 0d
Unscheduled
2011-01-09 2011-01-16 8 154d - -
Unscheduled
2010-08-08 2010-08-08 1 249d - -
Scheduled
2009-10-10 2009-12-02 54 37d 2009-10-10 0d
Unscheduled
2009-09-02 2009-09-03 2 459d - -
Scheduled
2008-04-12 2008-05-31 50 414d 2008-04-12 0d
Unscheduled
2007-02-16 2007-02-23 8 65d - -
Scheduled
2006-10-07 2006-12-13 68 109d 2006-10-06 +1d
Unscheduled
2006-06-14 2006-06-20 7 395d - -
Scheduled
2005-04-09 2005-05-15 37 455d 2005-04-08 +1d
Unscheduled
2004-01-09 2004-01-10 2 6d - -
Unscheduled
2003-12-18 2004-01-03 17 2d - -
Scheduled SGR/Major
2003-09-20 2003-12-16 88 400d 2003-09-20 0d
Unscheduled
2002-08-16 2002-08-16 1 110d - -
Scheduled
2002-03-23 2002-04-28 37 189d 2002-03-23 0d
Unscheduled
2001-09-13 2001-09-15 3 245d - -
Scheduled
2000-11-23 2001-01-11 50 265d 2000-11-23 0d
Unscheduled
2000-02-17 2000-03-03 16 180d - -
Unscheduled
1999-08-19 1999-08-21 3 42d - -
Scheduled
1999-05-20 1999-07-08 50 - 1999-05-20 0d
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