Monticello - Status & History

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

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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.
Oct2025NovDecJan2026FebMarAprMayJunJulAugSepOnline: Sep 12, 2025 to Dec 20, 2025Reduced Power: Dec 21, 2025 to Dec 23, 2025Online: Dec 24, 2025 to Feb 20, 2026Forced Outage: Feb 21, 2026 to Apr 2, 2026Power Ascension: Apr 3, 2026 to Apr 7, 2026Online: Apr 8, 2026 to Jul 27, 2026Reduced Power: Jul 28, 2026 to Aug 9, 2026Forced Outage: Aug 10, 2026 to Aug 27, 2026Power Ascension: Aug 28, 2026 to Aug 29, 2026Online: Aug 30, 2026 to Sep 12, 2026Today
OnlineReduced PowerPower AscensionForced 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
ranked of 93
Subscribers
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Days of continuous operation since the last outage ended. Clean run (no forced outages since last refueling).
16
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2019-05-13 to 2021-04-18).
706
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).
87.7%
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.
4.77 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.
2.7
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.
95.7%
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: 75/100 (#15/93)2022: 73/100 (#17/92)2023: 63/100 (#27/92)2024: 51/100 (#45/92)2025: 40/100 (#64/92)2026: 27/100 (#82/93) ↓ -12.2 pts vs 2025
Compare Monticello 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

Monticello has 44 outages plotted here, averaging 21 days each. The most recent, in Aug 2026, was a unplanned outage lasting 18 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, Monticello takes about 5 days to climb from first power back to full power. That average is drawn from 14 startups on record, and the most recent took 3 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 May 27, 2025

45.6% remaining 88.9 FPD margin
Monticello has an estimated 45.6% of its fuel left. Across its last 13 cycles, it has refueled with an average of 11.0% remaining.
Avg refuel: 11.0% Avg refuel (3yr): 4.3% Deepest burn: 2.7% (2019-05 → 2021-04) Most margin: 31.0% (2001-12 → 2003-04)
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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, Monticello has run at about 87.7% of its rated capacity. Across the last 12 reported months it averaged 80.5%. 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 Monticello, 44 in all since 1999. Of those, 14 were scheduled refueling outages and 30 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
Unscheduled
2026-08-10 2026-08-27 18 130d - -
Unscheduled
2026-02-21 2026-04-02 41 188d - -
Unscheduled
2025-08-14 2025-08-17 4 13d - -
Scram # 57832
2025-07-29 2025-08-01 4 56d - -
Unscheduled
2025-06-02 2025-06-03 2 9d - -
Scheduled M1R32
2025-04-19 2025-05-24 36 28d 2025-04-12 +7d
Scram # 57618
2025-03-20 2025-03-22 3 354d - -
Unscheduled
2024-03-27 2024-03-31 5 25d - -
Scram # 56995
2024-02-29 2024-03-02 3 146d - -
Scram # 56759
2023-09-28 2023-10-06 9 138d - -
Scheduled M1R31
2023-04-15 2023-05-13 29 16d 2023-04-15 0d
Unscheduled
2023-03-26 2023-03-30 5 423d - -
Unscheduled
2022-01-25 2022-01-27 3 251d - -
Scheduled M1R30
2021-04-18 2021-05-19 32 706d 2021-04-17 +1d
Scheduled M1R29
2019-04-14 2019-05-13 30 700d 2019-04-13 +1d
Scheduled M1R28
2017-04-15 2017-05-14 30 503d 2017-04-15 0d
Scram # 51560
2015-11-24 2015-11-29 6 180d - -
Scheduled M1R27
2015-04-13 2015-05-28 46 432d 2015-04-11 +2d
Unscheduled
2014-01-19 2014-02-05 18 185d - -
Scheduled M1R26SGR/Major
2013-03-02 2013-07-18 139 156d 2013-03-02 0d
Scram # 48341
2012-09-26 2012-09-27 2 40d - -
Unscheduled
2012-08-15 2012-08-17 3 251d - -
Unscheduled
2011-11-29 2011-12-08 10 2d - -
Scram # 47460
2011-11-20 2011-11-27 8 24d - -
Scram # 47364
2011-10-22 2011-10-27 6 117d - -
Unscheduled
2011-06-25 2011-06-27 3 34d - -
Scheduled M1R25SGR/Major
2011-03-05 2011-05-22 79 102d 2011-03-05 0d
Unscheduled
2010-11-18 2010-11-23 6 561d - -
Scheduled M1R24
2009-03-15 2009-05-06 53 170d 2009-03-16 -1d
Unscheduled
2008-09-12 2008-09-26 15 505d - -
Scheduled M1R23
2007-03-14 2007-04-26 44 50d 2007-03-13 +1d
Unscheduled
2007-01-11 2007-01-23 13 641d - -
Scheduled M1R22
2005-03-06 2005-04-10 36 258d 2005-03-05 +1d
Unscheduled
2004-06-19 2004-06-21 3 369d - -
Unscheduled
2003-06-15 2003-06-16 2 21d - -
Scheduled M1R21
2003-04-27 2003-05-25 29 457d 2003-04-27 0d
Unscheduled
2002-01-22 2002-01-25 4 40d - -
Scheduled M1R20
2001-11-04 2001-12-13 40 10d 2001-11-04 0d
Unscheduled
2001-10-24 2001-10-25 2 204d - -
Unscheduled
2001-02-26 2001-04-03 37 178d - -
Unscheduled
2000-08-28 2000-09-01 5 183d - -
Scheduled M1R19
2000-01-06 2000-02-27 53 224d 2000-01-06 0d
Unscheduled
1999-05-09 1999-05-27 19 10d - -
Unscheduled
1999-04-22 1999-04-29 8 - - -
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