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 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 (Started 2025-10-26). Clean run (no forced outages since last refueling).
317
Current Run
days ✔
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Longest recorded period of continuous operation between outages (1999-06-27 to 2001-02-03).
587
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.
7
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
90.2%
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), summed across every unit at this plant. Authoritative actuals, not an estimate.
16.91 TWh
Net Generation
EIA-923 · 12 mo to 2026-06 · plant total
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Total number of scheduled refueling outages detected in the historical data.
17
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.
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.
91.7%
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.
• 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:
Stable vs 2025
Compare Millstone 3 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
Millstone 3 has 41 outages plotted here, averaging 21 days each. The most recent, in Oct 2025, was a unplanned outage lasting 10 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, Millstone 3 takes about 4 days to climb from first power back to full power. That average is drawn from 17 startups on record, and the most recent took 4 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 19, 2025
8.4% remaining
17.2 FPD margin
Millstone 3 has an estimated 8.4% of its fuel left. Across its last 16 cycles, it has refueled with an average of 1.8% remaining.
Avg refuel: 1.8%
Avg refuel (3yr): 8.3%
Deepest burn: 0.0% (2001-03 → 2002-09)
Most margin: 8.3% (2023-12 → 2025-04)
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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, Millstone 3 has run at about 90.2% of its rated capacity. Across the last 12 reported months it averaged 96.9%. 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 Millstone 3, 41 in all since 1999. Of those, 17 were scheduled refueling outages and 24 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
|
2025-10-17 | 2025-10-26 | 10 | 75d | - | - |
|
Unscheduled
|
2025-08-01 | 2025-08-03 | 3 | 76d | - | - |
|
Scheduled
3R23
|
2025-04-11 | 2025-05-17 | 37 | 207d | 2025-04-13 | -2d |
|
Unscheduled
|
2024-09-04 | 2024-09-16 | 13 | 231d | - | - |
|
Unscheduled
|
2024-01-09 | 2024-01-17 | 9 | 32d | - | - |
|
Unscheduled
|
2023-12-03 | 2023-12-08 | 6 | 3d | - | - |
|
Scheduled
3R22
|
2023-10-20 | 2023-11-30 | 42 | 114d | 2023-10-14 | +6d |
|
Scram
# 56544
|
2023-05-31 | 2023-06-28 | 29 | 363d | - | - |
|
Scheduled
3R21
|
2022-04-08 | 2022-06-02 | 56 | 295d | 2022-04-07 | +1d |
|
Unscheduled
|
2021-06-11 | 2021-06-17 | 7 | 159d | - | - |
|
Unscheduled
|
2020-12-31 | 2021-01-03 | 4 | 50d | - | - |
|
Scheduled
3R20
|
2020-10-02 | 2020-11-11 | 41 | 171d | 2020-10-19 | -17d |
|
Scram
# 54663
|
2020-04-14 | 2020-04-14 | 1 | 4d | - | - |
|
Scram
# 54631
|
2020-04-02 | 2020-04-10 | 9 | 102d | - | - |
|
Unscheduled
|
2019-12-18 | 2019-12-22 | 5 | 218d | - | - |
|
Scheduled
3R19
|
2019-04-12 | 2019-05-14 | 33 | 515d | 2019-04-13 | -1d |
|
Scheduled
3R18
|
2017-10-13 | 2017-11-13 | 32 | 477d | 2017-10-08 | +5d |
|
Scram
# 52000
|
2016-06-13 | 2016-06-23 | 11 | 27d | - | - |
|
Scram
# 51929
|
2016-05-16 | 2016-05-17 | 2 | 4d | - | - |
|
Scheduled
3R17
|
2016-04-10 | 2016-05-12 | 33 | 73d | 2016-04-10 | 0d |
|
Scram
# 51682
|
2016-01-25 | 2016-01-28 | 4 | 435d | - | - |
|
Scheduled
3R16
|
2014-10-12 | 2014-11-16 | 36 | 132d | 2014-10-12 | 0d |
|
Scram
# 50141
|
2014-05-26 | 2014-06-02 | 8 | 286d | - | - |
|
Scram
# 49260
|
2013-08-10 | 2013-08-13 | 4 | 85d | - | - |
|
Scheduled
3R15
|
2013-04-14 | 2013-05-17 | 34 | 509d | 2013-04-14 | 0d |
|
Scheduled
3R14
|
2011-10-09 | 2011-11-22 | 45 | 419d | 2011-10-09 | 0d |
|
Unscheduled
|
2010-08-15 | 2010-08-16 | 2 | 89d | - | - |
|
Unscheduled
|
2010-05-18 | 2010-05-18 | 1 | 2d | - | - |
|
Scheduled
3R13
|
2010-04-11 | 2010-05-16 | 36 | 96d | 2010-04-04 | +7d |
|
Unscheduled
|
2009-12-20 | 2010-01-05 | 17 | 392d | - | - |
|
Scheduled
3R12
|
2008-10-12 | 2008-11-23 | 43 | 513d | 2008-10-12 | 0d |
|
Scheduled
3R11
|
2007-04-07 | 2007-05-18 | 42 | 68d | 2007-04-07 | 0d |
|
Unscheduled
|
2007-01-29 | 2007-01-29 | 1 | 421d | - | - |
|
Unscheduled
|
2005-12-02 | 2005-12-04 | 3 | 36d | - | - |
|
Scheduled
3R10
|
2005-09-30 | 2005-10-27 | 28 | 153d | 2005-09-29 | +1d |
|
Unscheduled
|
2005-04-18 | 2005-04-30 | 13 | 347d | - | - |
|
Scheduled
3R9
|
2004-04-03 | 2004-05-06 | 34 | 461d | 2004-04-02 | +1d |
|
Unscheduled
|
2002-12-23 | 2002-12-29 | 7 | 80d | - | - |
|
Scheduled
3R8
|
2002-09-07 | 2002-10-04 | 28 | 527d | 2002-09-07 | 0d |
|
Scheduled
3R7
|
2001-02-03 | 2001-03-29 | 55 | 587d | 2001-02-03 | 0d |
|
Unscheduled
|
1999-05-02 | 1999-06-27 | 57 | - | - | - |
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