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Count of currently-Operating US nuclear units with at least 2 completed refueling cycles of historical data. Newer units (e.g., Vogtle 4, which started commercial operation in 2024) need a second refuel before they can be ranked — they appear in the count once they have data.
93
Units Ranked
Active operating fleet
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Fleet-wide average fuel utilization = 100% minus the average refuel-point fuel %. Measures the fraction of each unit's typical cycle (calendar days from refuel to refuel) that produced full-power generation, after accounting for startup, derates, forced outages, and coastdown. Higher is more efficient. The fleet median is shown below the average for distribution context.
97.1%
Fleet Avg Utilization
median 98.1%
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Highest fuel utilization in the fleet — the operator that consistently burns the most of each fuel cycle before refueling, leaving the smallest reactivity margin at refuel. A 100% utilization is essentially impossible (every unit has some derate or startup ramp), so this number indicates the practical ceiling for US operators.
99.8%
Top Utilization
Oconee 1
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Fleet-wide average startup duration — typical days from first power generation (>0%) post-refuel to sustained full power (≥95% for 2+ consecutive days). Computed as a robust mean per unit (drops outliers like post-major-outage startups), then averaged across the fleet. Lower is faster restart.
5.0d
Fleet Avg Startup
median 4.2d
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Fastest typical startup duration in the fleet — the operator with the shortest median-time from first power back to sustained full power after refueling. Reflects operating discipline and post-refuel testing efficiency. Outlier startups (like post-major-outage cycles) are excluded so this is the unit's repeatable performance, not its best-ever single restart.
2.1d
Fastest Startup
Oconee 1
Across 93 reactors with enough cycle history, the fleet burns about 97.1% of its designed fuel cycle before refueling and gets back to full power in about 5.0 days after an outage. Oconee 1 leads on both fuel use (99.8%) and restart speed (about 2.1 days).
Fuel Utilization Leaders % of designed cycle burned before refueling
| # | Unit | Utilization | Avg Refuel % | Cycles |
|---|---|---|---|---|
| 1 | Oconee 1 | 99.8% | 0.2% | 15 |
| 2 | LaSalle 2 | 99.3% | 0.7% | 14 |
| 3 | Braidwood 2 | 99.2% | 0.8% | 18 |
| 4 | McGuire 1 | 99.2% | 0.8% | 17 |
| 5 | Point Beach 1 | 99.2% | 0.8% | 17 |
| 6 | Byron 1 | 99.1% | 0.9% | 18 |
| 7 | Byron 2 | 99.1% | 0.9% | 17 |
| 8 | Harris 1 | 99.1% | 0.9% | 17 |
| 9 | Point Beach 2 | 99.1% | 0.9% | 17 |
| 10 | Surry 1 | 99.1% | 0.9% | 17 |
| 11 | Ginna | 98.9% | 1.1% | 18 |
| 12 | North Anna 1 | 98.9% | 1.1% | 17 |
| 13 | Salem 2 | 98.9% | 1.1% | 18 |
| 14 | Surry 2 | 98.9% | 1.1% | 18 |
| 15 | Catawba 1 | 98.8% | 1.2% | 18 |
| 16 | Limerick 2 | 98.8% | 1.2% | 13 |
| 17 | Beaver Valley 1 | 98.7% | 1.3% | 17 |
| 18 | Beaver Valley 2 | 98.7% | 1.3% | 18 |
| 19 | Braidwood 1 | 98.7% | 1.3% | 17 |
| 20 | Catawba 2 | 98.7% | 1.3% | 17 |
| 21 | Palo Verde 3 | 98.7% | 1.3% | 17 |
| 22 | Arkansas Nuclear 2 | 98.6% | 1.4% | 18 |
| 23 | Farley 1 | 98.6% | 1.4% | 17 |
| 24 | Robinson 2 | 98.6% | 1.4% | 15 |
| 25 | Salem 1 | 98.6% | 1.4% | 17 |
| 26 | Palo Verde 1 | 98.5% | 1.5% | 17 |
| 27 | South Texas 2 | 98.5% | 1.5% | 18 |
| 28 | Dresden 2 | 98.4% | 1.6% | 13 |
| 29 | Watts Bar 2 | 98.4% | 1.6% | 5 |
| 30 | Calvert Cliffs 1 | 98.3% | 1.7% | 13 |
| 31 | Comanche Peak 2 | 98.3% | 1.7% | 18 |
| 32 | McGuire 2 | 98.3% | 1.7% | 18 |
| 33 | Millstone 2 | 98.3% | 1.7% | 17 |
| 34 | Peach Bottom 3 | 98.3% | 1.7% | 13 |
| 35 | Seabrook 1 | 98.3% | 1.7% | 18 |
| 36 | D.C. Cook 2 | 98.2% | 1.8% | 16 |
| 37 | Davis-Besse | 98.2% | 1.8% | 12 |
| 38 | Saint Lucie 1 | 98.2% | 1.8% | 17 |
| 39 | Susquehanna 2 | 98.2% | 1.8% | 13 |
| 40 | Turkey Point 4 | 98.2% | 1.8% | 17 |
| 41 | Browns Ferry 2 | 98.1% | 1.9% | 13 |
| 42 | Farley 2 | 98.1% | 1.9% | 17 |
| 43 | Oconee 3 | 98.1% | 1.9% | 15 |
| 44 | Quad Cities 1 | 98.1% | 1.9% | 14 |
| 45 | Turkey Point 3 | 98.1% | 1.9% | 17 |
| 46 | Vogtle 1 | 98.1% | 1.9% | 18 |
| 47 | Vogtle 2 | 98.1% | 1.9% | 17 |
| 48 | Brunswick 2 | 97.9% | 2.1% | 13 |
| 49 | LaSalle 1 | 97.9% | 2.1% | 12 |
| 50 | Limerick 1 | 97.9% | 2.1% | 13 |
| 51 | Oconee 2 | 97.9% | 2.1% | 15 |
| 52 | Palo Verde 2 | 97.9% | 2.1% | 18 |
| 53 | Wolf Creek 1 | 97.9% | 2.1% | 18 |
| 54 | Comanche Peak 1 | 97.7% | 2.3% | 17 |
| 55 | Diablo Canyon 2 | 97.7% | 2.3% | 16 |
| 56 | FitzPatrick | 97.6% | 2.4% | 12 |
| 57 | Brunswick 1 | 97.5% | 2.5% | 13 |
| 58 | Callaway | 97.5% | 2.5% | 17 |
| 59 | Columbia Generating Station | 97.5% | 2.5% | 13 |
| 60 | Dresden 3 | 97.4% | 2.6% | 13 |
| 61 | Cooper | 97.3% | 2.7% | 14 |
| 62 | D.C. Cook 1 | 97.3% | 2.7% | 15 |
| 63 | Peach Bottom 2 | 97.3% | 2.7% | 12 |
| 64 | Calvert Cliffs 2 | 97.2% | 2.8% | 13 |
| 65 | Quad Cities 2 | 97.2% | 2.8% | 13 |
| 66 | Diablo Canyon 1 | 97.1% | 2.9% | 16 |
| 67 | Sequoyah 2 | 97.0% | 3.0% | 17 |
| 68 | South Texas 1 | 97.0% | 3.0% | 17 |
| 69 | Nine Mile Point 2 | 96.9% | 3.1% | 13 |
| 70 | Nine Mile Point 1 | 96.8% | 3.2% | 13 |
| 71 | Hatch 2 | 96.5% | 3.5% | 13 |
| 72 | Clinton | 96.4% | 3.6% | 15 |
| 73 | Saint Lucie 2 | 96.0% | 4.0% | 17 |
| 74 | Susquehanna 1 | 96.0% | 4.0% | 13 |
| 75 | Fermi 2 | 95.8% | 4.2% | 16 |
| 76 | Hatch 1 | 95.8% | 4.2% | 14 |
| 77 | Hope Creek 1 | 95.8% | 4.2% | 17 |
| 78 | Prairie Island 2 | 95.8% | 4.2% | 14 |
| 79 | Sequoyah 1 | 95.7% | 4.3% | 17 |
| 80 | Monticello | 95.4% | 4.6% | 13 |
| 81 | North Anna 2 | 95.1% | 4.9% | 17 |
| 82 | Browns Ferry 1 | 94.7% | 5.3% | 8 |
| 83 | Summer | 94.7% | 5.3% | 18 |
| 84 | Browns Ferry 3 | 94.1% | 5.9% | 13 |
| 85 | Arkansas Nuclear 1 | 94.0% | 6.0% | 17 |
| 86 | Vogtle 3 | 93.9% | 6.1% | 2 |
| 87 | Perry 1 | 93.8% | 6.2% | 13 |
| 88 | River Bend 1 | 93.1% | 6.9% | 14 |
| 89 | Millstone 3 | 92.8% | 7.2% | 16 |
| 90 | Grand Gulf 1 | 92.2% | 7.8% | 15 |
| 91 | Watts Bar 1 | 86.7% | 13.3% | 18 |
| 92 | Waterford 3 | 86.3% | 13.7% | 17 |
| 93 | Prairie Island 1 | 83.3% | 16.7% | 14 |
Fastest Startups Days from first power to sustained 95%+ (outliers excluded)
| # | Unit | Typical Startup | Sample | Outliers |
|---|---|---|---|---|
| 1 | Oconee 1 | 2.1d | 10 | — |
| 2 | Oconee 3 | 2.3d | 10 | 1 |
| 3 | Davis-Besse | 2.7d | 10 | 1 |
| 4 | Saint Lucie 2 | 2.7d | 10 | 3 |
| 5 | Millstone 2 | 2.8d | 10 | 1 |
| 6 | McGuire 1 | 2.9d | 10 | 1 |
| 7 | Oconee 2 | 2.9d | 10 | — |
| 8 | Peach Bottom 3 | 2.9d | 10 | 2 |
| 9 | Dresden 3 | 3.0d | 10 | — |
| 10 | Harris 1 | 3.1d | 10 | — |
| 11 | North Anna 2 | 3.1d | 10 | 1 |
| 12 | Braidwood 2 | 3.2d | 10 | — |
| 13 | Catawba 1 | 3.2d | 10 | — |
| 14 | LaSalle 2 | 3.2d | 10 | 1 |
| 15 | Surry 2 | 3.2d | 10 | 1 |
| 16 | Byron 2 | 3.3d | 10 | — |
| 17 | Calvert Cliffs 1 | 3.3d | 10 | — |
| 18 | Calvert Cliffs 2 | 3.3d | 10 | — |
| 19 | Wolf Creek 1 | 3.3d | 10 | — |
| 20 | Catawba 2 | 3.4d | 10 | — |
| 21 | LaSalle 1 | 3.4d | 10 | 1 |
| 22 | Quad Cities 1 | 3.4d | 10 | 2 |
| 23 | Saint Lucie 1 | 3.4d | 10 | 1 |
| 24 | Comanche Peak 1 | 3.5d | 10 | — |
| 25 | Surry 1 | 3.5d | 10 | — |
| 26 | South Texas 2 | 3.6d | 10 | 2 |
| 27 | Vogtle 1 | 3.6d | 10 | 1 |
| 28 | Vogtle 2 | 3.6d | 10 | — |
| 29 | Callaway | 3.7d | 10 | — |
| 30 | Palo Verde 1 | 3.7d | 10 | — |
| 31 | Braidwood 1 | 3.8d | 10 | — |
| 32 | Peach Bottom 2 | 3.8d | 10 | — |
| 33 | Arkansas Nuclear 2 | 3.9d | 10 | — |
| 34 | FitzPatrick | 3.9d | 10 | 1 |
| 35 | Millstone 3 | 3.9d | 10 | 1 |
| 36 | Seabrook 1 | 3.9d | 10 | — |
| 37 | Arkansas Nuclear 1 | 4.0d | 10 | 3 |
| 38 | Salem 1 | 4.0d | 10 | — |
| 39 | Byron 1 | 4.1d | 10 | — |
| 40 | McGuire 2 | 4.1d | 10 | 1 |
| 41 | Nine Mile Point 2 | 4.1d | 10 | 1 |
| 42 | Quad Cities 2 | 4.1d | 10 | — |
| 43 | Sequoyah 1 | 4.1d | 10 | 1 |
| 44 | Summer | 4.1d | 10 | 1 |
| 45 | Limerick 2 | 4.2d | 10 | — |
| 46 | Nine Mile Point 1 | 4.2d | 10 | 1 |
| 47 | North Anna 1 | 4.2d | 10 | — |
| 48 | Beaver Valley 2 | 4.3d | 10 | — |
| 49 | Comanche Peak 2 | 4.5d | 10 | — |
| 50 | Ginna | 4.5d | 10 | — |
| 51 | Limerick 1 | 4.7d | 10 | — |
| 52 | Palo Verde 3 | 4.7d | 10 | — |
| 53 | Point Beach 1 | 4.8d | 10 | 1 |
| 54 | Prairie Island 1 | 4.8d | 10 | — |
| 55 | Watts Bar 2 | 4.8d | 5 | 1 |
| 56 | Beaver Valley 1 | 5.0d | 10 | — |
| 57 | Sequoyah 2 | 5.0d | 10 | 1 |
| 58 | Dresden 2 | 5.1d | 10 | — |
| 59 | Point Beach 2 | 5.1d | 10 | — |
| 60 | Diablo Canyon 2 | 5.2d | 10 | 1 |
| 61 | Browns Ferry 1 | 5.3d | 9 | 2 |
| 62 | D.C. Cook 2 | 5.4d | 10 | — |
| 63 | Palo Verde 2 | 5.5d | 10 | — |
| 64 | Farley 2 | 5.6d | 10 | — |
| 65 | D.C. Cook 1 | 5.7d | 10 | — |
| 66 | Hope Creek 1 | 5.7d | 10 | — |
| 67 | Robinson 2 | 5.7d | 10 | — |
| 68 | Turkey Point 3 | 5.7d | 10 | — |
| 69 | Salem 2 | 5.8d | 10 | — |
| 70 | South Texas 1 | 5.8d | 10 | — |
| 71 | Monticello | 6.0d | 10 | — |
| 72 | Vogtle 3 | 6.0d | 3 | 1 |
| 73 | Diablo Canyon 1 | 6.1d | 10 | 1 |
| 74 | Turkey Point 4 | 6.1d | 10 | 2 |
| 75 | Watts Bar 1 | 6.1d | 10 | — |
| 76 | Hatch 1 | 6.3d | 10 | 1 |
| 77 | Prairie Island 2 | 6.3d | 10 | 1 |
| 78 | Cooper | 6.5d | 10 | — |
| 79 | Fermi 2 | 6.7d | 10 | 1 |
| 80 | Clinton | 7.0d | 10 | — |
| 81 | Farley 1 | 7.5d | 10 | — |
| 82 | Brunswick 1 | 7.7d | 10 | — |
| 83 | Browns Ferry 2 | 7.9d | 10 | 1 |
| 84 | Waterford 3 | 7.9d | 10 | — |
| 85 | Hatch 2 | 8.1d | 10 | 1 |
| 86 | Susquehanna 2 | 8.2d | 10 | 1 |
| 87 | Perry 1 | 8.3d | 10 | — |
| 88 | Browns Ferry 3 | 8.9d | 10 | — |
| 89 | Brunswick 2 | 9.5d | 10 | — |
| 90 | Susquehanna 1 | 11.2d | 10 | 1 |
| 91 | Columbia Generating Station | 11.5d | 10 | — |
| 92 | River Bend 1 | 12.3d | 10 | 1 |
| 93 | Grand Gulf 1 | 14.2d | 10 | 1 |
Operational Excellence Composite Leaderboard 7-metric composite + year-over-year trend (5-metric apples-to-apples)
Oconee 1 tops the composite ranking with a score of 90 out of 100, blending reliability, efficiency, and operating discipline. The table below ranks the full fleet.
Composite ranks across the active US fleet on a 7-metric 5-year window (Reliability, Efficiency, Discipline). The Trend (YoY) column compares this year's score to last year's, computed on a 5-metric apples-to-apples subset (point-in-time fuel utilization & startup excluded since they have no historical record). Threshold for "stable": < 2 points. Click a column header to sort. · trend cache 2026-08-01
Efficiency Map Higher utilization + faster startup = more efficient operator (lower-right is best)
Each dot plots a reactor by how fully it burns its fuel (right is better) against its typical startup time (lower is faster). Units toward the lower-right corner both use their fuel efficiently and restart quickly.