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Oconee 2 - Status & History

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

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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.
65
Excellence
#24 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).
166
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2015-11-11 to 2017-10-28).
717
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (617 days for this 24-month cycle unit) with no trips to 0% power.
5
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
92.7%
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.
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.
100.0%
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
65/100
Top Quartile · #24/94
5-year window

Oconee 2 ranks #24 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Startup Duration (94th percentile). Weakest: Scrams (5-year) (30th percentile).

Reliability
71
Capacity factor + Forced outages + B2B streaks
Efficiency
63
Fuel utilization + Refuel duration
Discipline
62
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 87th
94.9% (higher better, Reliability)
Forced Outage Days/yr 35th
5.6d (lower better, Reliability)
B2B Avg Streak 92th
706d (higher better, Reliability)
Fuel Utilization 46th
97.9% (higher better, Efficiency)
Refuel Duration 79th
24d (lower better, Efficiency)
Startup Duration 94th
2.9d (lower better, Discipline)
Scrams (5-year) 30th
0.6/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: 72/100 (#19/93)2022: 44/100 (#55/92)2023: 58/100 (#32/92)2024: 59/100 (#28/93)2025: 60/100 (#26/94)2026: 60/100 (#27/94) Stable vs 2025
Compare Oconee 2 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 26, 2025

76.8% remaining 163 / 701 days 0.3 FPD margin
Avg refuel: 16.7% Avg refuel (3yr): 0.0% Deepest burn: 0.0% (2015-11 → 2017-10) Most margin: 31.8% (2002-11 → 2004-03)
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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

Scheduled
2025-10-28 2025-11-25 29 707d 2025-11-01 -4d
Scheduled
2023-10-28 2023-11-21 25 609d 2023-10-28 0d
Scram # 55733
2022-02-05 2022-02-26 22 55d - -
Scram # 55638
2021-12-10 2021-12-12 3 3d - -
Scheduled
2021-11-13 2021-12-07 25 703d 2021-10-16 +28d
Scheduled
2019-11-09 2019-12-11 33 714d 2019-10-28 +12d
Scheduled
2017-10-28 2017-11-25 29 717d 2017-10-28 0d
Scheduled
2015-10-17 2015-11-11 26 82d 2015-10-17 0d
Unscheduled
2015-07-27 2015-07-27 1 285d - -
Unscheduled
2014-10-14 2014-10-15 2 314d - -
Scheduled
2013-10-12 2013-12-04 54 695d 2013-10-12 0d
Scheduled
2011-10-22 2011-11-17 27 507d 2011-10-22 0d
Unscheduled
2010-05-31 2010-06-02 3 2d - -
Scheduled
2010-04-25 2010-05-29 35 500d 2010-04-24 +1d
Scheduled
2008-10-25 2008-12-11 48 207d 2008-10-25 0d
Unscheduled
2008-04-01 2008-04-01 1 307d - -
Scheduled
2007-04-28 2007-05-30 33 70d 2007-04-27 +1d
Unscheduled
2007-02-16 2007-02-17 2 305d - -
Unscheduled
2006-04-13 2006-04-17 5 136d - -
Scheduled
2005-10-22 2005-11-28 38 496d 2005-10-21 +1d
Scheduled SGR/Major
2004-03-20 2004-06-13 86 484d 2004-03-19 +1d
Scheduled
2002-10-12 2002-11-22 42 501d 2002-10-12 0d
Scheduled
2001-04-26 2001-05-29 34 489d 2001-04-26 0d
Unscheduled
1999-12-24 1999-12-24 1 2d - -
Unscheduled
1999-12-22 1999-12-22 1 7d - -
Scheduled
1999-11-04 1999-12-15 42 135d 1999-11-04 0d
Unscheduled
1999-06-20 1999-06-22 3 110d - -
Unscheduled
1999-03-01 1999-03-02 2 3d - -
Unscheduled
1999-02-24 1999-02-26 3 - - -
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