Millstone
Millstone is a nuclear plant in New London County, Connecticut, operated by Dominion Energy Nuclear Conn Inc. No other power plant in Connecticut has more nameplate capacity; the state has 182 in all. Within the ISO New England balancing area it is the largest of 1,475 plants. Its biggest unit, rated at 1,350 MW, is the largest single generator in Connecticut. Ownership is shared by three organizations; the largest stake, 56%, is held by Dominion Energy Nuclear Conn Inc.
Nameplate capacity, 2025
2,260 MW
2,108 MW net summer capacity
2 operable units
- Nuclear2,260 MW100%
Unit by unit, 1975 to 2025
operating in 2025bar height follows unit size
Among Connecticut’s plants
Largest plants in the state by nameplate capacity, with the plants ranked next to this one.
- 1Millstonethis plant
- 2CPV Towantic Energy Center842 MW
- 3Lake Road Generating Plant840 MW
Other rankings
- All US power plants
- 54th of 14,286
- US nuclear plants
- 21st of 56
Operable units
| Unit | Technology | Nameplate | Summer | Online | Status |
|---|---|---|---|---|---|
| 2 | Nuclear | 910 MW | 863 MW | 1975 | Operating |
| 3 | Nuclear | 1,350 MW | 1,245 MW | 1986 | Operating |
Who owns it
Shares are weighted by the nameplate capacity of each unit an owner holds.
| Owner | Share of capacity |
|---|---|
| Dominion Energy Nuclear Conn Inc | 55.8% |
| Massachusetts Mun Wholes Electric Co | 2.9% |
| Green Mountain Power Corp | 1.0% |
| Dominion Energy Nuclear Conn Inc (sole owner of the other units) | 40.3% |
Grid and site
- Balancing area
- ISO New England
- Reliability region
- Northeast Power Coordinating Council
- Highest grid connection voltage
- 345 kV
- Water source
- Long Island Sound
- Nearest town on record
- Waterford
- Operator type
- Independent producer
- Coordinates
- 41.311°N, 72.168°W
Closest plants
| Plant | Runs on | Capacity | Distance |
|---|---|---|---|
| Yale New Haven - New London | Natural gas | 1.8 MW | 3.7 mi northeast |
| Pfizer Groton Plant | Natural gas | 37.5 MW | 4.8 mi east |
| Pfizer Groton Fuel Cell | Natural gas | 5.6 MW | 5.3 mi east |
| Bridge Street 1 & 2 | Oil and petroleum | 5.2 MW | 5.7 mi northeast |
| Connecticut College | Natural gas | 1.2 MW | 5.9 mi northeast |
| CMEEC - Polaris Park Solar Hybrid | Solar | 4.3 MW | 6.8 mi northeast |
| Water Treatment 1 & 2 | Oil and petroleum | 5.2 MW | 7.0 mi east |
| CMEEC - Navy NE Trident | Solar | 1 MW | 7.4 mi northeast |