Cooper

Refueling Outage · Day 15

Nebraska Public Power District·Brownville, NE·BWR·772 MWe

Outage History Daily Power Log Get alerts

Reactor Status Timeline

Refueling Outage · Day 15 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.
Nov2025DecJan2026FebMarAprMayJunJulAugSepOctReduced Power: Oct 12, 2025Online: Oct 13, 2025 to Nov 7, 2025Reduced Power: Nov 8, 2025Online: Nov 9, 2025 to Feb 13, 2026Reduced Power: Feb 14, 2026Online: Feb 15, 2026 to May 1, 2026Reduced Power: May 2, 2026Online: May 3, 2026 to May 29, 2026Reduced Power: May 30, 2026Online: May 31, 2026 to Jun 24, 2026Reduced Power: Jun 25, 2026 to Jun 28, 2026Online: Jun 29, 2026 to Jul 10, 2026Reduced Power: Jul 11, 2026Online: Jul 12, 2026 to Jul 24, 2026Reduced Power: Jul 25, 2026Online: Jul 26, 2026 to Aug 12, 2026Coastdown: Aug 13, 2026 to Sep 27, 2026Refueling Outage (RE 34): Sep 28, 2026 to Oct 12, 2026RE 34Today
OnlineReduced PowerCoastdownRefueling Outage
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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
Rank locked · 93 units
Subscribers
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Days of continuous operation since the last outage ended. Has forced outage(s) since last refueling.
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Current Run
offline
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Longest recorded period of continuous operation between outages (2020-11-03 to 2022-10-02).
698
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.
4
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
89.4%
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.
6.87 TWh
Net Generation
EIA-923 · 12 mo to 2026-07
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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.
3.3
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.
98.2%
Fuel Utilization
3yr avg

Reactor Status

Current Reactor Status Oct 9, 2026

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Current power output from NRC daily reactor status reports, updated Monday through Friday, except federal holidays. The gauge shows power level as a percentage of rated capacity. The sparkline shows the last 14 days of power history. Click to view the full unit dashboard.
Cooper is OFFLINE (12 Days) at 0% of rated power as of Oct 9, 2026. This outage is RFO RE 34. Over the last 14 reported days it has run between 0% and 81% power.
Cooper is OFFLINE (12 Days) Get alerts
0
PERCENT
0 100 200 300 400 500 600 700 772 RATED CAPACITY (772 MWe) 0 MWe
Current:
0 MWe
Powering 0 homes
Rated Capacity:
772 MWe
617,600 homes
Report Age: 3 days ago
14-Day Power History
81
81
0
0
0
0
0
0
0
0
0
0
0
0
Sep 26 Oct 9

Capacity Factor (365-Day)

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0%
Current
94.2%
365-Day Avg
#81
of 94 plants
Min: 0% Max: 100% 22 days <80%

Outage Days by Year

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Total days spent in outage each year, split by scheduled refueling (blue) and forced/unplanned (red). Lower totals indicate better reliability and outage execution. Hover for details.
Across its recorded history, Cooper has spent 665 days in scheduled refueling outages and 169 days in forced or unplanned outages. Taller bars mark the years with the most downtime.
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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

Cooper has 42 outages plotted here, averaging 20 days each. The most recent, in Sep 2026, was a scheduled refueling outage lasting 12 days.
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Scheduled refueling outage durations over time. Green bars are at or below this unit's average, amber up to 30% above it, red beyond that. The dashed line is the average. Shorter outages mean better execution.

Refueling Duration Trend

Cooper has completed 16 scheduled refueling outages on record, averaging 42 days each. The most recent, in Sep 2026, ran 12 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, Cooper takes about 6 days to climb from first power back to full power. That average is drawn from 15 startups on record, and the most recent took 3 days.
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Daily reactor power over the 120 days before each scheduled refueling outage, one line per refueling, lined up on the day the outage began. A coastdown is the slow decline as the fuel runs out near the end of a cycle. The highlighted line is the most recent refueling and fainter lines are older. Counts and medians cover coastdowns of a week or longer. A shutdown straight from full power, with no decline ahead of it, is what a forced outage looks like.

Coastdown Before Refueling

13 of 16 refuelings 33 days median 85% power at shutdown 0.3% per day
Cooper coasted down for a week or longer before 13 of its 16 refuelings on record. Those coastdowns ran a median of 33 days and ended near 85% power. The most recent refueling, in Sep 2026, followed a 46-day coastdown from 97% to 81%.
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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, Cooper has run at about 89.4% of its rated capacity. Across the last 12 reported months it averaged 88.4%. On the chart, green stretches near the top are full-power running, amber marks reduced power (50 to 89%), and red drops toward zero are outages.

Outage History & Daily Power Log

This table logs every recorded outage for Cooper, 42 in all since 1999. Of those, 16 were scheduled refueling outages and 26 were unplanned or forced. The typical outage lasted about 20 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
Scheduled RE 34
2026-09-28 In Outage 12+ 694d 2026-09-26 +2d
Scheduled RE 33
2024-09-29 2024-11-03 36 650d 2024-09-28 +1d
Scram # 56278 Manual
2022-12-17 2022-12-19 3 34d - -
Scheduled RE 32
2022-10-02 2022-11-13 43 698d 2022-10-01 +1d
Scram # 54976 Manual
2020-11-02 2020-11-03 2 7d - -
Scheduled RE 31
2020-09-27 2020-10-26 30 682d 2020-09-26 +1d
Scheduled RE 30
2018-09-30 2018-11-15 47 117d 2018-09-29 +1d
Unscheduled
2018-05-30 2018-06-05 7 75d - -
Unscheduled
2018-03-12 2018-03-16 5 491d - -
Scheduled RE 29
2016-09-25 2016-11-06 43 482d 2016-09-25 0d
Unscheduled
2015-05-30 2015-06-01 3 210d - -
Scheduled RE 28
2014-09-28 2014-11-01 35 116d 2014-09-27 +1d
Unscheduled
2014-05-30 2014-06-04 6 549d - -
Scheduled RE 27
2012-10-14 2012-11-27 45 526d 2012-10-01 +13d
Scheduled RE 26
2011-03-13 2011-05-07 56 485d 2011-03-12 +1d
Unscheduled
2009-11-12 2009-11-13 2 4d - -
Unscheduled
2009-11-07 2009-11-08 2 3d - -
Scheduled RE 25
2009-09-26 2009-11-04 40 200d 2009-09-26 0d
Unscheduled
2009-03-06 2009-03-10 5 207d - -
Unscheduled
2008-08-09 2008-08-11 3 84d - -
Scheduled RE 24
2008-04-12 2008-05-17 36 327d 2008-04-12 0d
Unscheduled
2007-05-19 2007-05-21 3 179d - -
Scheduled RE 23
2006-10-21 2006-11-21 32 150d 2006-10-20 +1d
Unscheduled
2006-05-23 2006-05-24 2 84d - -
Unscheduled
2006-02-26 2006-02-28 3 154d - -
Unscheduled
2005-09-23 2005-09-25 3 159d - -
Unscheduled
2005-04-16 2005-04-17 2 58d - -
Scheduled RE 22
2005-01-15 2005-02-17 34 69d 2005-01-15 0d
Unscheduled
2004-10-20 2004-11-07 19 322d - -
Unscheduled
2003-11-29 2003-12-03 5 27d - -
Unscheduled
2003-10-28 2003-11-02 6 120d - -
Scheduled RE 21
2003-05-27 2003-06-30 35 35d 2003-05-27 0d
Unscheduled
2003-04-21 2003-04-22 2 6d - -
Unscheduled
2003-02-24 2003-04-15 51 280d - -
Unscheduled
2002-05-15 2002-05-20 6 137d - -
Scheduled RE 20
2001-11-04 2001-12-29 56 233d 2001-11-04 0d
Unscheduled
2001-03-16 2001-03-16 1 3d - -
Unscheduled
2001-03-04 2001-03-13 10 137d - -
Unscheduled
2000-10-14 2000-10-18 5 140d - -
Scheduled RE 19SGR/Major
2000-03-04 2000-05-27 85 50d 2000-03-04 0d
Unscheduled
2000-01-09 2000-01-14 6 107d - -
Unscheduled
1999-09-18 1999-09-24 7 - - -
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