Free benchmark
Nuclear Availability Index
How much of the U.S. nuclear fleet is actually producing, as a single number. 100 means the fleet is running flat out; lower means more megawatts offline. Updated every morning, free to cite.
Baseload NAI · Jun 16, 2026
99.5
1-day +0.8
7-day +2.5
NAI, last 12 months
The seasonal dips are spring and fall refueling, when utilities take units down in the mild shoulder seasons.
By ISO / region, today
lowest availability first| ISO / Region | NAI | MW offline | Nuclear capacity | Units |
|---|---|---|---|---|
| MISO | 97.8 | 259 | 11,512 | 13 |
| Florida Power & Light (FPL) | 98.1 | 69 | 3,649 | 4 |
| PJM | 99.6 | 128 | 32,692 | 31 |
| TVA | 100.0 | 0 | 8,181 | 7 |
| Duke Progress (CPLE) | 100.0 | 0 | 3,593 | 4 |
| Duke Carolinas (DUK) | 100.0 | 0 | 7,226 | 7 |
| Bonneville (BPAT) | 100.0 | 0 | 1,151 | 1 |
| ERCOT | 100.0 | 0 | 4,986 | 4 |
| SPP | 100.0 | 0 | 1,948 | 2 |
| CAISO | 100.0 | 0 | 2,240 | 2 |
| Southern (SOCO) | 100.0 | 0 | 8,080 | 8 |
| NYISO | 100.0 | 0 | 3,326 | 4 |
| ISO-NE | 100.0 | 0 | 3,352 | 3 |
| Palo Verde / SRP | 100.0 | 0 | 3,937 | 3 |
| Dominion SC (SCEG) | 100.0 | 0 | 977 | 1 |
Methodology & citation
The NAI is U.S. nuclear generation divided by available nuclear capacity, expressed as a percent, summed over every operating unit reporting that day. It is the positive framing of "MW offline": an NAI of 96.0 means 4% of the fleet's capacity is offline for refueling, maintenance or a forced outage. Source data is the NRC Daily Power Reactor Status Report and EIA net-summer capacity, updated every morning. It is an availability measure, not a forecast.
Cite as: NukeGryd Nuclear Availability Index (NAI), 99.5 as of Jun 16, 2026. NukeGryd, NukeWorker.com.