Columbia Generating Station - Status & History

Comprehensive reactor performance metrics, cycle analysis, and historical outage data.
Data refreshed 2.3h ago Rx Status: Sep 17, 2026 at 7:49 AM (M-F)

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Reactor Status Timeline

Online NRC data, Mon to Fri ? Actual daily reactor status from NRC reports (Mon to Fri) and the current state. What is coming -- the utility's published Scheduled outage and NukeWorker's model Projection -- is part of a subscription. Colored by status. How far ahead you can see depends on your plan.
Oct2025NovDecJan2026FebMarAprMayJunJulAugSepOctOnline: Sep 17, 2025 to Dec 12, 2025Reduced Power: Dec 13, 2025Online: Dec 14, 2025 to Feb 12, 2026Scram: Feb 13, 2026 to Feb 16, 2026Reduced Power: Feb 17, 2026 to Feb 18, 2026Online: Feb 19, 2026 to Feb 20, 2026Power Ascension: Feb 21, 2026Online: Feb 22, 2026 to May 4, 2026Reduced Power: May 5, 2026 to May 7, 2026Online: May 8, 2026 to Jun 20, 2026Reduced Power: Jun 21, 2026Online: Jun 22, 2026 to Sep 17, 2026Scram (reactor trip): Feb 12, 2026Today
OnlineReduced PowerPower AscensionScram⚡Scram (reactor trip)
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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.
   
Excellence
ranked of 93
Subscribers
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Days of continuous operation since the last outage ended (Started 2026-02-16). Clean run (no forced outages since last refueling).
213
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2019-06-17 to 2021-05-09).
692
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold set for this unit with no trips to 0% power.
3
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
86.4%
Capacity Factor
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Net electricity actually generated over the most recent 12 months reported by the U.S. EIA (Form EIA-923). Authoritative actuals, not an estimate.
9.79 TWh
Net Generation
EIA-923 · 12 mo to 2026-06
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Total number of scheduled refueling outages detected in the historical data.
14
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.
8.3
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.
94.5%
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 measured 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
5-yr trend: 2021: 41/100 (#62/93)2022: 51/100 (#48/92)2023: 58/100 (#31/92)2024: 56/100 (#33/92)2025: 50/100 (#44/92)2026: 41/100 (#59/93) ↓ -8.9 pts vs 2025
Compare Columbia Generating Station 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

Columbia Generating Station has 46 outages plotted here, averaging 21 days each. The most recent, in Feb 2026, was a unplanned outage lasting 4 days.
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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

After a refueling outage, Columbia Generating Station takes about 13 days to climb from first power back to full power. That average is drawn from 14 startups on record, and the most recent took 16 days.
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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 Jun 17, 2025

35.8% remaining 17.1 FPD margin
Columbia Generating Station has an estimated 35.8% of its fuel left. Across its last 13 cycles, it has refueled with an average of 8.0% remaining.
Avg refuel: 8.0% Avg refuel (3yr): 5.5% Deepest burn: 2.7% (2013-06 → 2015-05) Most margin: 17.2% (2011-09 → 2013-05)
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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

Over its operating life, Columbia Generating Station has run at about 86.4% of its rated capacity. Across the last 12 reported months it averaged 97.8%. On the chart, flat stretches near the top are full-power running and drops to zero are outages.
This table logs every recorded outage for Columbia Generating Station, 46 in all since 1999. Of those, 14 were scheduled refueling outages and 32 were unplanned or forced. The typical outage lasted about 21 days. Where the Scheduled column shows (Model), the date is a NukeWorker projection because the utility had not published one.
Type ⇅ Actual Start ⇅ Actual End ⇅ Duration ⇅ Days Online ⇅ Scheduled Delta
Scram # 58163
2026-02-13 2026-02-16 4 230d - -
Unscheduled
2025-06-24 2025-06-28 5 11d - -
Scheduled R27
2025-04-12 2025-06-13 63 664d 2025-05-11 -29d
Scheduled R26
2023-05-06 2023-06-18 44 510d 2023-05-05 +1d
Unscheduled
2021-12-07 2021-12-12 6 173d - -
Scheduled R25
2021-05-09 2021-06-17 40 692d 2021-05-07 +2d
Scheduled R24
2019-05-12 2019-06-17 37 354d 2019-05-15 -3d
Scram # 53410
2018-05-19 2018-05-23 5 261d - -
Scram # 52918
2017-08-21 2017-08-31 11 67d - -
Scheduled R23
2017-05-14 2017-06-15 33 141d 2017-05-13 +1d
Scram # 52442
2016-12-19 2016-12-24 6 264d - -
Scram # 51826
2016-03-29 2016-03-30 2 278d - -
Scheduled R22
2015-05-10 2015-06-25 47 687d 2015-05-06 +4d
Scheduled R21
2013-05-12 2013-06-22 42 349d 2013-05-09 +3d
Unscheduled
2012-05-21 2012-05-28 8 245d - -
Scheduled R20SGR/Major
2011-04-03 2011-09-19 170 507d 2011-04-06 -3d
Unscheduled
2009-11-08 2009-11-12 5 38d - -
Unscheduled
2009-09-29 2009-10-01 3 29d - -
Unscheduled
2009-08-06 2009-08-31 26 37d - -
Unscheduled
2009-06-27 2009-06-30 4 7d - -
Scheduled R19
2009-05-09 2009-06-20 43 86d 2009-05-10 -1d
Unscheduled
2009-02-09 2009-02-12 4 82d - -
Unscheduled
2008-11-16 2008-11-19 4 85d - -
Unscheduled
2008-08-22 2008-08-23 2 419d - -
Unscheduled
2007-06-29 2007-06-30 2 6d - -
Scheduled R18
2007-05-13 2007-06-23 42 31d 2007-05-12 +1d
Unscheduled
2007-04-10 2007-04-12 3 155d - -
Unscheduled
2006-11-01 2006-11-06 6 489d - -
Unscheduled
2005-06-24 2005-06-30 7 3d - -
Unscheduled
2005-06-16 2005-06-21 6 7d - -
Scheduled R17
2005-05-07 2005-06-09 34 260d 2005-05-06 +1d
Unscheduled
2004-08-18 2004-08-20 3 2d - -
Unscheduled
2004-08-16 2004-08-16 1 2d - -
Unscheduled
2004-07-31 2004-08-14 15 395d - -
Unscheduled
2003-07-01 2003-07-02 2 7d - -
Scheduled R16
2003-05-04 2003-06-24 52 52d 2003-05-04 0d
Unscheduled
2003-03-01 2003-03-13 13 371d - -
Unscheduled
2002-02-15 2002-02-23 9 198d - -
Unscheduled
2001-07-27 2001-08-01 6 26d - -
Unscheduled
2001-06-29 2001-07-01 3 5d - -
Scheduled R15
2001-05-20 2001-06-24 36 241d 2001-05-20 0d
Unscheduled
2000-09-19 2000-09-21 3 14d - -
Unscheduled
2000-09-02 2000-09-05 4 61d - -
Unscheduled
2000-06-27 2000-07-03 7 249d - -
Unscheduled
1999-09-19 1999-10-22 34 80d - -
Scheduled R14
1999-04-18 1999-07-01 75 - 1999-04-18 0d
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