Byron 2 - Status & History

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

Plant Info Outage History Daily Power Log
?
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.
88
Excellence
#3 of 94 →
Top Quartile
?
Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
378
Current Run
days ✔
?
Longest recorded period of continuous operation between outages (2020-10-19 to 2022-04-18).
546
Record Run
days
?
Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (468 days for this 18-month cycle unit) with no trips to 0% power.
11
B2B Runs
79% toward B2B (370/468d)
?
Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
95%
Capacity Factor
?
Total number of scheduled refueling outages detected in the historical data.
18
Outages
since 1999
?
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.
3.7
Avg Startup
days (last 3)
?
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.
99.4%
Fuel Utilization
3yr avg
?
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
88/100
Top Quartile · #3/94
5-year window

Byron 2 ranks #3 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Refuel Duration (97th percentile). Weakest: B2B Avg Streak (57th percentile).

Reliability
83
Capacity factor + Forced outages + B2B streaks
Efficiency
95
Fuel utilization + Refuel duration
Discipline
87
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #2 of 61 PWR
Containment: #2 of 48 Dry Ambient (PWR)
Cycle length: #1 of 54 18-month cycle
Fleet rank above (3 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 97th
96.6% (higher better, Reliability)
Forced Outage Days/yr 95th
0.6d (lower better, Reliability)
B2B Avg Streak 57th
532d (higher better, Reliability)
Fuel Utilization 92th
99.1% (higher better, Efficiency)
Refuel Duration 97th
17d (lower better, Efficiency)
Startup Duration 83th
3.3d (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: 91/100 (#1/93)2022: 92/100 (#1/92)2023: 90/100 (#3/92)2024: 90/100 (#3/93)2025: 90/100 (#2/94)2026: 90/100 (#2/94) Stable vs 2025
Compare Byron 2 head-to-head with up to 3 other units. Compare now
?
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

?
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

?
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

?
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 2, 2025

29.8% remaining 376 / 534 days 1.0 FPD margin
Avg refuel: 3.0% Avg refuel (3yr): 0.6% Deepest burn: 0.0% (2008-10 → 2010-04) Most margin: 7.8% (2010-05 → 2011-09)
?
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
2025-04-14 2025-05-01 18 536d 2025-04-14 0d
Scheduled
2023-10-09 2023-10-26 18 516d 2023-10-09 0d
Scheduled
2022-04-18 2022-05-11 24 546d 2022-04-11 +7d
Scheduled
2020-10-05 2020-10-19 15 531d 2020-10-05 0d
Scheduled
2019-04-08 2019-04-23 16 534d 2019-04-08 0d
Scheduled
2017-10-02 2017-10-21 20 354d 2017-10-02 0d
Scram # 52295
2016-10-13 2016-10-13 1 150d - -
Scheduled
2016-04-18 2016-05-16 29 543d 2016-04-18 0d
Scheduled
2014-09-29 2014-10-23 25 518d 2014-09-29 0d
Scheduled
2013-04-08 2013-04-29 22 18d 2013-04-08 0d
Scram # 48838
2013-03-21 2013-03-21 1 408d - -
Scram # 47624
2012-01-31 2012-02-07 8 114d - -
Scheduled
2011-09-19 2011-10-09 21 116d 2011-09-19 0d
Unscheduled
2011-05-23 2011-05-26 4 381d - -
Scheduled
2010-04-19 2010-05-07 19 543d 2010-04-19 0d
Scheduled
2008-10-06 2008-10-23 18 342d 2008-10-06 0d
Unscheduled
2007-10-20 2007-10-30 11 171d - -
Scheduled
2007-04-02 2007-05-02 31 530d 2007-04-01 +1d
Unscheduled Startup Hold
2005-10-19 2005-10-19 1 7d - -
Scheduled
2005-09-26 2005-10-12 17 536d 2005-09-25 +1d
Scheduled
2004-03-23 2004-04-08 17 533d 2004-03-22 +1d
Scheduled
2002-09-17 2002-10-07 21 82d 2002-09-17 0d
Unscheduled
2002-06-23 2002-06-27 5 427d - -
Scheduled
2001-04-07 2001-04-22 16 254d 2001-04-07 0d
Unscheduled
2000-07-27 2000-07-27 1 195d - -
Unscheduled
2000-01-13 2000-01-14 2 59d - -
Scheduled
1999-10-23 1999-11-15 24 - 1999-10-23 0d
Page created in 0.123 seconds with 7 queries.