South Texas 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.
58
Excellence
#33 of 94 →
Mid Quartile
?
Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
170
Current Run
days ✔
?
Longest recorded period of continuous operation between outages (2021-04-19 to 2022-10-08).
537
Record Run
days
?
Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (456 days for this 18-month cycle unit) with no trips to 0% power.
10
B2B Runs
?
Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
89%
Capacity Factor
?
Total number of scheduled refueling outages detected in the historical data.
19
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.
6.7
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.
99.5%
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
58/100
Mid Quartile · #33/94
5-year window

South Texas 2 ranks #33 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: Fuel Utilization (72th percentile). Weakest: B2B Avg Streak (37th percentile).

Reliability
53
Capacity factor + Forced outages + B2B streaks
Efficiency
63
Fuel utilization + Refuel duration
Discipline
60
Startup duration + Scram count
Cohort Rankings apples-to-apples comparison within each peer group
Reactor type: #21 of 61 PWR
Containment: #18 of 48 Dry Ambient (PWR)
Cycle length: #16 of 54 18-month cycle
Fleet rank above (33 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor 62th
92.4% (higher better, Reliability)
Forced Outage Days/yr 59th
2.8d (lower better, Reliability)
B2B Avg Streak 37th
508d (higher better, Reliability)
Fuel Utilization 72th
98.5% (higher better, Efficiency)
Refuel Duration 53th
32d (lower better, Efficiency)
Startup Duration 72th
3.6d (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: 70/100 (#21/93)2022: 67/100 (#23/92)2023: 71/100 (#18/92)2024: 57/100 (#31/93)2025: 51/100 (#40/94)2026: 51/100 (#42/94) Stable vs 2025
Compare South Texas 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 Nov 6, 2025

63.5% remaining 188 / 502 days 4.7 FPD margin
Avg refuel: 8.4% Avg refuel (3yr): 0.5% Deepest burn: 0.0% (2001-04 → 2002-10) Most margin: 58.6% (2013-04 → 2013-11)
?
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
Scram # 58054
2025-11-22 2025-11-25 4 17d - -
Scheduled
2025-10-04 2025-11-05 33 503d 2025-10-07 -3d
Scram # 57124
2024-05-13 2024-05-19 7 4d - -
Scheduled
2024-03-23 2024-05-09 48 500d 2024-03-21 +2d
Scheduled
2022-10-08 2022-11-09 33 537d 2022-10-07 +1d
Scheduled
2021-03-21 2021-04-19 30 503d 2021-03-19 +2d
Scheduled
2019-10-05 2019-11-04 31 527d 2019-10-04 +1d
Scheduled
2018-03-25 2018-04-26 33 501d 2018-03-24 +1d
Scheduled
2016-10-09 2016-11-09 32 521d 2016-10-08 +1d
Scheduled
2015-03-29 2015-05-07 40 463d 2015-03-28 +1d
Scheduled
2013-11-17 2013-12-21 35 212d 2013-11-16 +1d
Unscheduled
2013-04-14 2013-04-19 6 2d - -
Scheduled SGR/Major
2013-01-09 2013-04-12 94 3d 2013-04-29 (Enhanced) -110d (Enhanced)
Scram # 48659
2013-01-05 2013-01-06 2 259d - -
Scram # 47485
2011-11-29 2012-04-21 145 8d - -
Scheduled
2011-10-30 2011-11-21 23 339d 2011-10-28 +2d
Unscheduled
2010-11-04 2010-11-25 22 187d - -
Scheduled
2010-03-28 2010-05-01 35 182d 2010-03-28 0d
Unscheduled
2009-09-18 2009-09-27 10 318d - -
Scheduled
2008-10-05 2008-11-04 31 527d 2008-10-05 0d
Scheduled
2007-03-25 2007-04-27 34 510d 2007-03-25 0d
Scheduled
2005-10-02 2005-10-31 30 228d 2005-10-01 +1d
Unscheduled
2005-02-10 2005-02-16 7 289d - -
Scheduled
2004-03-31 2004-04-27 28 385d 2004-03-31 0d
Unscheduled
2003-01-25 2003-03-12 47 4d - -
Unscheduled
2002-12-16 2003-01-21 37 12d - -
Scheduled
2002-10-02 2002-12-04 64 86d 2002-10-02 0d
Unscheduled
2002-07-08 2002-07-08 1 22d - -
Unscheduled
2002-06-15 2002-06-16 2 249d - -
Unscheduled
2001-10-04 2001-10-09 6 146d - -
Unscheduled
2001-05-09 2001-05-11 3 38d - -
Scheduled
2001-03-07 2001-04-01 26 5d 2001-03-07 0d
Unscheduled
2001-03-02 2001-03-02 1 21d - -
Unscheduled
2001-02-08 2001-02-09 2 459d - -
Scheduled
1999-10-13 1999-11-07 26 - 1999-10-13 0d
Page created in 0.085 seconds with 7 queries.