Millstone
New London County, Connecticut · EIA plant ID 566 · Operator: Dominion Nuclear Conn Inc
Nameplate2,260MWSummer 2,108 MW
Generators2in service
Net generation16,999GWh12 mo to Aug 2026
Capacity factor92%nuclear units, summer MW
Heat rate—thermal plants only
First online1975
The 12-month figures include preliminary EIA-923 months, which EIA revises. Final data runs through Dec 2025.
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), nuclear units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 15,427.8 | 87.8% | — |
| 2002 | 14,918.3 | 84.9% | — |
| 2003 | 16,078.1 | 91.9% | — |
| 2004 | 16,539.1 | 92.4% | — |
| 2005 | 15,562.1 | 87.2% | — |
| 2006 | 16,589.4 | 93.0% | — |
| 2007 | 16,386.1 | 92.5% | — |
| 2008 | 15,432.9 | 87.2% | — |
| 2009 | 16,657.4 | 90.4% | — |
| 2010 | 16,750.3 | 91.0% | — |
| 2011 | 15,927.8 | 86.5% | — |
| 2012 | 17,077.9 | 92.5% | — |
| 2013 | 17,079.6 | 92.7% | — |
| 2014 | 15,840.6 | 85.2% | — |
| 2015 | 17,410.9 | 95.2% | — |
| 2016 | 16,575.5 | 90.4% | — |
| 2017 | 16,499.6 | 90.2% | — |
| 2018 | 16,881.5 | 93.0% | — |
| 2019 | 16,733.4 | 92.1% | — |
| 2020 | 15,714.9 | 86.3% | — |
| 2021 | 17,216.5 | 93.7% | — |
| 2022 | 16,464.2 | 89.2% | — |
| 2023 | 13,669.5 | 75.0% | — |
| 2024 | 16,870.3 | 91.3% | — |
| 2025 | 16,708.7 | 90.5% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| 2 | Nuclear | ST | 909.9 | 863.4 | Dec 1975 | Operating | — | coming soon |
| 3 | Nuclear | ST | 1,350 | 1,245 | Apr 1986 | Operating | — | coming soon |
Owner / operator
Operator: Dominion Nuclear Conn Inc. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| Dominion Energy Nuclear Conn Inc | 55.8% | 1,262 MW |
| Dominion Nuclear Conn Inc | 40.3% | 910 MW |
| Massachusetts Mun Wholes Electric Co | 2.9% | 65 MW |
| Green Mountain Power Corp | 1.0% | 23 MW |
Nearby plants
Within 80 km.
| Yale New Haven - New London | 2 MW | 5.9 km |
| Pfizer Groton Plant | 38 MW | 7.8 km |
| Pfizer Groton Fuel Cell | 6 MW | 8.5 km |
| Bridge Street 1 & 2 | 5 MW | 9.2 km |
| Connecticut College | 1 MW | 9.5 km |
| Groton Flanders Road Landfill | — | 10.8 km |