Grand Gulf 1
Online · 100% powerEntergy·Port Gibson, MS·BWR·1,401 MWe
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.OnlineReduced PowerCoastdownPower AscensionRefueling 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 (Started 2026-03-26). Clean run (no forced outages since last refueling).
198
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2010-05-24 to 2012-02-20).
637
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.
1
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
83.6%
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.
10.16 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.
8
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.
97.2%
Fuel Utilization
3yr avg
Reactor Status
Capacity Factor (365-Day)
100%
Current
86.9%
365-Day Avg
#75
of 94 plants
Min: 0%
Max: 100%
53 days <80%
Outage Days by Year
?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, Grand Gulf 1 has spent 724 days in scheduled refueling outages and 528 days in forced or unplanned outages. Taller bars mark the years with the most downtime.
Performance Trends
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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
Grand Gulf 1 has 79 outages plotted here, averaging 16 days each. The most recent, in Feb 2026, was a scheduled refueling outage lasting 41 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
Grand Gulf 1 has completed 16 scheduled refueling outages on record, averaging 45 days each. The most recent, in Feb 2026, ran 41 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, Grand Gulf 1 takes about 10 days to climb from first power back to full power. That average is drawn from 16 startups on record, and the most recent took 12 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
6 of 16 refuelings
19 days median
89% power at shutdown
0.3% per day
Grand Gulf 1 coasted down for a week or longer before 6 of its 16 refuelings on record. Those coastdowns ran a median of 19 days and ended near 89% power. The most recent refueling, in Feb 2026, followed a 14-day coastdown from 97% to 94%.
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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 Mar 28, 2026
71.4% remaining
3.5 FPD margin
Grand Gulf 1 has an estimated 71.4% of its fuel left. Across its last 15 cycles, it has refueled with an average of 20.2% remaining.
Avg refuel: 20.2%
Avg refuel (3yr): 2.8%
Deepest burn: 1.8% (2014-03 → 2016-02)
Most margin: 37.2% (2016-03 → 2018-04)
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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, Grand Gulf 1 has run at about 83.6% of its rated capacity. Across the last 12 reported months it averaged 86.8%. 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.
Estimated reactivity remaining in Grand Gulf 1's current fuel cycle, shown as a stylized fuel rod that drains as the cycle progresses. The cycle starts when the unit returns to power after its most recent refueling outage, and the gauge represents the fraction of that cycle's typical effective full-power days (EFPD) still available. Days at less than 100% power burn fuel proportionally — so a unit with significant downtime (high burn deficit) drains slower and ends with MORE reactivity left, giving operators margin to coast down (extend the cycle by reducing power) instead of refueling on the calendar. The dashed red line near the bottom marks the rough industry coastdown threshold (~15% remaining). Cycle target is the unit's median recent cycle length. Source: NRC daily reactor status reports cross-referenced against scheduled refuel outage history.
Fuel Burn Down Cycle since Mar 28, 2026
Grand Gulf 1 is 195 days into its current fuel cycle with an estimated 71.4% of its fuel left. Its typical cycle runs about 669 days.
Fresh — 100%
Refuel — 0%
71.4% remaining
Fresh fuel
Cycle progress
195 / 669 days
EFPD remaining
477 days
Effective burn
192 EFPD
Burn deficit
3.5 FPD
Grand Gulf 1 is early in its fuel cycle with 477 EFPD of reactivity remaining. Refuel is not expected for many months.
Outage History & Daily Power Log
This table logs every recorded outage for Grand Gulf 1, 79 in all since 1999. Of those, 16 were scheduled refueling outages and 63 were unplanned or forced. The typical outage lasted about 16 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 |
|---|---|---|---|---|---|---|
| 2026-02-14 | 2026-03-26 | 41 | 241d | 2026-02-26 | -12d | |
| 2025-06-18 | 2025-06-18 | 1 | 116d | - | - | |
| 2025-02-16 | 2025-02-22 | 7 | 88d | - | - | |
| 2024-11-11 | 2024-11-20 | 10 | 227d | - | - | |
|
Scheduled
RF24
|
2024-03-02 | 2024-03-29 | 28 | 60d | 2024-03-01 | +1d |
| 2023-12-17 | 2024-01-02 | 17 | 361d | - | - | |
| 2022-12-20 | 2022-12-21 | 2 | 121d | - | - | |
|
Unscheduled
|
2022-08-20 | 2022-08-21 | 2 | 15d | - | - |
|
Unscheduled
|
2022-07-13 | 2022-08-05 | 24 | 11d | - | - |
| 2022-07-01 | 2022-07-02 | 2 | 62d | - | - | |
|
Scheduled
RF23SGR/Major
|
2022-02-27 | 2022-04-30 | 63 | 302d | 2022-02-24 | +3d |
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Unscheduled
|
2021-04-21 | 2021-05-01 | 11 | 129d | - | - |
| 2020-12-12 | 2020-12-13 | 2 | 10d | - | - | |
| 2020-11-06 | 2020-12-02 | 27 | 71d | - | - | |
| 2020-08-25 | 2020-08-27 | 3 | 2d | - | - | |
| 2020-08-08 | 2020-08-23 | 16 | 70d | - | - | |
| 2020-05-26 | 2020-05-30 | 5 | 5d | - | - | |
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Scheduled
RF22SGR/Major
|
2020-02-23 | 2020-05-21 | 89 | 82d | 2020-02-22 | +1d |
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Unscheduled
|
2019-11-28 | 2019-12-03 | 6 | 3d | - | - |
|
Unscheduled
|
2019-11-16 | 2019-11-25 | 10 | 182d | - | - |
| 2019-05-13 | 2019-05-18 | 6 | 77d | - | - | |
| 2019-02-24 | 2019-02-25 | 2 | 70d | - | - | |
| 2018-12-13 | 2018-12-16 | 4 | 87d | - | - | |
| 2018-09-15 | 2018-09-17 | 3 | 66d | - | - | |
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Scheduled
RF21SGR/Major
|
2018-04-07 | 2018-07-11 | 96 | 64d | 2018-04-14 | -7d |
| 2018-01-31 | 2018-02-02 | 3 | 15d | - | - | |
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Unscheduled
|
2018-01-14 | 2018-01-16 | 3 | 2d | - | - |
|
Unscheduled
|
2018-01-09 | 2018-01-12 | 4 | 30d | - | - |
|
Unscheduled
|
2017-12-06 | 2017-12-10 | 5 | 4d | - | - |
|
Unscheduled
|
2017-11-17 | 2017-12-02 | 16 | 48d | - | - |
|
Unscheduled
|
2017-08-30 | 2017-09-30 | 32 | 139d | - | - |
| 2017-04-04 | 2017-04-13 | 10 | 66d | - | - | |
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Unscheduled
|
2016-09-09 | 2017-01-28 | 142 | 51d | - | - |
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Unscheduled
|
2016-07-11 | 2016-07-20 | 10 | 3d | - | - |
| 2016-06-26 | 2016-07-08 | 13 | 8d | - | - | |
| 2016-06-17 | 2016-06-18 | 2 | 79d | - | - | |
| 2016-03-30 | 2016-03-30 | 1 | 4d | - | - | |
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Scheduled
RF20
|
2016-02-20 | 2016-03-26 | 36 | 371d | 2016-02-21 | -1d |
| 2015-02-08 | 2015-02-14 | 7 | 315d | - | - | |
| 2014-03-30 | 2014-03-30 | 1 | 10d | - | - | |
| 2014-03-18 | 2014-03-20 | 3 | 4d | - | - | |
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Scheduled
RF19
|
2014-02-10 | 2014-03-14 | 33 | 98d | 2014-02-09 | +1d |
|
Unscheduled
|
2013-11-02 | 2013-11-04 | 3 | 21d | - | - |
|
Unscheduled
|
2013-10-11 | 2013-10-12 | 2 | 3d | - | - |
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Unscheduled
|
2013-10-05 | 2013-10-08 | 4 | 64d | - | - |
| 2013-07-31 | 2013-08-02 | 3 | 184d | - | - | |
| 2013-01-15 | 2013-01-28 | 14 | 8d | - | - | |
| 2013-01-05 | 2013-01-07 | 3 | 6d | - | - | |
| 2012-12-29 | 2012-12-30 | 2 | 15d | - | - | |
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Unscheduled
|
2012-12-09 | 2012-12-14 | 6 | 183d | - | - |
|
Unscheduled
|
2012-06-08 | 2012-06-09 | 2 | 2d | - | - |
| 2012-02-20 | 2012-06-06 | 108 | 637d | 2012-02-19 | +1d | |
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Scheduled
RF17
|
2010-04-26 | 2010-05-24 | 29 | 47d | 2010-03-14 | +43d |
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Unscheduled
|
2010-03-09 | 2010-03-10 | 2 | 498d | - | - |
| 2008-10-27 | 2008-10-27 | 1 | 7d | - | - | |
|
Scheduled
RF16
|
2008-09-22 | 2008-10-20 | 29 | 184d | 2008-09-18 | +4d |
|
Unscheduled
|
2008-03-22 | 2008-03-22 | 1 | 25d | - | - |
|
Unscheduled
|
2008-02-23 | 2008-02-26 | 4 | 39d | - | - |
|
Unscheduled
|
2008-01-13 | 2008-01-15 | 3 | 121d | - | - |
|
Unscheduled
|
2007-09-01 | 2007-09-14 | 14 | 10d | - | - |
|
Unscheduled
|
2007-08-22 | 2007-08-22 | 1 | 90d | - | - |
|
Unscheduled
|
2007-05-20 | 2007-05-24 | 5 | 39d | - | - |
|
Scheduled
RF15
|
2007-03-19 | 2007-04-11 | 24 | 294d | 2007-03-18 | +1d |
|
Unscheduled
|
2006-05-23 | 2006-05-29 | 7 | 218d | - | - |
|
Scheduled
RF14
|
2005-09-19 | 2005-10-17 | 29 | 218d | 2005-09-18 | +1d |
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Unscheduled
|
2005-02-12 | 2005-02-13 | 2 | 327d | - | - |
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Scheduled
RF13
|
2004-02-23 | 2004-03-22 | 29 | 301d | 2004-02-22 | +1d |
|
Unscheduled
|
2003-04-25 | 2003-04-28 | 4 | 84d | - | - |
|
Unscheduled
|
2003-01-31 | 2003-01-31 | 1 | 118d | - | - |
|
Scheduled
RF12
|
2002-09-14 | 2002-10-05 | 22 | 82d | 2002-09-14 | 0d |
|
Unscheduled
|
2002-06-23 | 2002-06-24 | 2 | 297d | - | - |
|
Unscheduled
|
2001-08-29 | 2001-08-30 | 2 | 4d | - | - |
|
Unscheduled
|
2001-08-24 | 2001-08-25 | 2 | 16d | - | - |
|
Unscheduled
|
2001-08-08 | 2001-08-08 | 1 | 96d | - | - |
|
Scheduled
RF11
|
2001-04-14 | 2001-05-04 | 21 | 208d | 2001-04-14 | 0d |
|
Unscheduled
|
2000-09-16 | 2000-09-18 | 3 | 283d | - | - |
|
Scheduled
RF10
|
1999-10-23 | 1999-12-08 | 47 | 236d | 1999-10-23 | 0d |
|
Unscheduled
|
1999-02-22 | 1999-03-01 | 8 | 26d | - | - |
|
Unscheduled
|
1999-01-14 | 1999-01-27 | 14 | - | - | - |
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