Website: [DominionEnergy.com/Millstone](https://www.dominionenergy.com/safety/nuclear-safety/millstone-preparedness) ### Introduction Millstone Power Station is located in Waterford, Connecticut, on the shores of Long Island Sound. It is the only nuclear power plant in Connecticut and the only multi-unit nuclear facility in New England. The plant consists of two operational units, Millstone 2 and Millstone 3, which began commercial operation in 1975 and 1986, respectively. The facility is owned and operated by Dominion Energy, a publicly traded company (ticker: D) based in Richmond, Virginia. Dominion acquired the plant in 2000 from Northeast Utilities, marking a significant transition in its ownership history. Construction of Millstone began in the late 1960s, with Unit 1 (decommissioned in 1998) starting in 1966, Unit 2 in 1969, and Unit 3 in 1974. The plant faced challenges during its early years, including regulatory scrutiny and public opposition due to safety concerns, particularly in the 1990s when Unit 1 was shut down following operational issues. Notable events include temporary shutdowns of Units 2 and 3 in the mid-1990s due to safety violations and management issues, which led to significant reforms under new ownership. Currently, Millstone Power Station remains operational, providing a substantial portion of Connecticut’s electricity and contributing to the regional grid in New England. As of recent reports, it produces roughly one-third of the state’s electricity, underscoring its critical role in the energy landscape [CT Mirror](https://ctmirror.org/2025/10/09/millstone-nuclear-power-plant-50-years/). ### Technical Specifications | Specification | Details | |-------------------------|--------------------------------------| | Reactor Type | Pressurized Water Reactor (PWR) | | Reactor Model | Unit 2: Combustion Engineering; Unit 3: [[Westinghouse Electric Company|Westinghouse]] 4-loop | | Number of Units | 2 (Units 2 and 3 operational; Unit 1 decommissioned) | | Net Capacity (MWe) | Unit 2: 882 MWe; Unit 3: 1,227 MWe; Total: ~2,109 MWe | | Thermal Capacity (MWt) | Unit 2: 2,700 MWt; Unit 3: 3,650 MWt | | Cooling System | Once-through cooling using Long Island Sound | | Fuel Type | Enriched Uranium Dioxide (UO2) | | Commercial Operation | Unit 2: December 26, 1975; Unit 3: April 23, 1986 | | Grid Connection | Connected to ISO New England grid | Data sourced from [NRC.gov](https://www.nrc.gov/info-finder/reactors/mill3) and [Wikipedia](https://en.wikipedia.org/wiki/Millstone_Nuclear_Power_Plant). ### Licensing and Regulatory Status - **Original Operating License Date and Expiration**: Millstone Unit 2 received its operating license on September 26, 1975, with an original expiration date of September 26, 2015. Millstone Unit 3 received its license on January 31, 1986, with an original expiration of January 31, 2026. - **License Renewal Status**: Both units have received license renewals from the Nuclear Regulatory Commission (NRC). Unit 2’s license is extended to July 31, 2035, and Unit 3’s to November 25, 2045, allowing for a total of 60 years of operation per unit. - **Current NRC Oversight Status**: Millstone is under routine NRC oversight with no significant unresolved issues as of the latest reports. The plant is subject to regular inspections and performance reviews. - **Ongoing Regulatory Issues**: There are no major ongoing regulatory issues reported in recent NRC updates or news. The plant has maintained compliance with safety and operational standards post-renewal [NRC.gov](https://www.nrc.gov/info-finder/reactors/mill3). ### Ownership and Operations - **Current Owner/Operator**: Dominion Energy, through its subsidiary Dominion Nuclear Connecticut, Inc., owns and operates Millstone Power Station. - **Parent Company Financial Position**: Dominion Energy is a publicly traded utility (NYSE: D) with a market capitalization of approximately $48 billion as of late 2025. The company has a diversified energy portfolio, including nuclear, natural gas, and renewables, and has maintained stable financial performance despite market fluctuations. - **Employment and Economic Impact**: Millstone supports over 3,900 direct and indirect jobs in Connecticut, contributing significantly to the local economy through wages, taxes, and procurement. - **Annual Generation**: The plant generates enough electricity to power about 2 million homes annually, accounting for over half of Connecticut’s electricity consumption [Wikipedia](https://en.wikipedia.org/wiki/Millstone_Nuclear_Power_Plant). ### Recent News and Developments | Date | Event | Details | |-----------------|-------------------------------|-------------------------------------------------------------------------| | October 9, 2025 | 50-Year Anniversary | Millstone celebrated 50 years of operation, highlighting its role in providing one-third of Connecticut’s electricity [CT Mirror](https://ctmirror.org/2025/10/09/millstone-nuclear-power-plant-50-years/). | | June 2024 | Routine Maintenance Outage | Unit 2 underwent a scheduled refueling and maintenance outage, completed without incident, ensuring continued reliability. | | April 2023 | Safety Inspection | NRC conducted a biennial safety inspection, confirming compliance with [[Federal|federal]] regulations and no significant findings. | | January 2023 | Community Engagement | Dominion Energy hosted public forums to discuss emergency preparedness and plant safety updates for local residents. | | March 2022 | Economic Impact Study | A state report reaffirmed Millstone’s critical role in Connecticut’s economy, supporting thousands of jobs and energy stability. | These events reflect Millstone’s ongoing commitment to safety, reliability, and community engagement, with no major adverse incidents reported in the past two years. Information is compiled from various news sources and [DominionEnergy.com](https://www.dominionenergy.com/safety/nuclear-safety/millstone-preparedness). ### Safety and Emergency Planning - **Emergency Planning Zone (EPZ) Details**: The EPZ for Millstone includes a 10-mile radius around the plant, covering parts of Waterford, New London, and surrounding towns. Emergency plans are coordinated with state and local authorities, including evacuation routes and public notification systems [DominionEnergy.com](https://www.dominionenergy.com/safety/nuclear-safety/millstone-preparedness). - **Notable Safety Features or Upgrades**: Millstone has implemented post-Fukushima safety enhancements, including additional backup power systems and improved flood protection measures. Both units feature robust containment structures designed to withstand severe events. - **Historical Safety Incidents**: In the 1990s, Millstone faced significant safety concerns, leading to temporary shutdowns of Units 2 and 3 due to management and procedural issues. Unit 1 was permanently shut down in 1998 after failing to meet safety standards. Since Dominion’s acquisition in 2000, safety performance has improved, with no major incidents reported in recent decades [Wikipedia](https://en.wikipedia.org/wiki/Millstone_Nuclear_Power_Plant). ### Decommissioning Status (if applicable) - **Unit 1 Shutdown Date and Reason**: Millstone Unit 1, a boiling water reactor (BWR), was permanently shut down on July 21, 1998, due to economic unviability and safety concerns following regulatory scrutiny. - **Decommissioning Method and Timeline**: Unit 1 is in SAFSTOR status, a deferred dismantling method where the reactor is maintained in a safe condition until full decommissioning, currently projected for completion by 2050. Radioactive components are secured on-site. - **Spent Fuel Storage Status**: Spent fuel from Unit 1, along with operational units, is stored in dry cask storage on-site, managed under NRC regulations. - **Site Reuse Potential**: Portions of the 500-acre site not used for active operations or storage could potentially be repurposed for renewable energy projects or industrial use post-decommissioning, though no specific plans are confirmed [NRC.gov](https://www.nrc.gov/info-finder/reactors/mill3). ### New Hampshire Relevance Millstone Power Station holds significant relevance to [[New Hampshire]] due to its role in the regional energy grid and proximity to the state. Located approximately 100 miles from New Hampshire’s southern border, Millstone contributes to the ISO New England (ISO-NE) grid, which serves all six New England states, including New Hampshire. It provides a stable baseload power supply, helping to meet regional demand and stabilize electricity prices, which directly benefits New Hampshire consumers. Additionally, Millstone’s operational history offers lessons for New Hampshire’s nuclear policy, particularly concerning [[Seabrook Station]], the state’s only nuclear plant. Both facilities are PWRs operated under similar regulatory frameworks, and Millstone’s successful license renewals and post-Fukushima safety upgrades could inform strategies for Seabrook’s long-term operation. Millstone’s economic impact, supporting thousands of jobs, also mirrors Seabrook’s importance to New Hampshire’s economy. Furthermore, discussions around small modular reactors (SMRs) in New England could draw from Millstone’s operational and safety track record as a benchmark for future deployments, though New Hampshire-specific policies would need separate consideration. Overall, Millstone’s reliability and challenges provide a comparative case study for New Hampshire’s energy planning within the shared regional grid. ### Competitive Position Compared to other nuclear plants in the region, such as Seabrook Station in New Hampshire and the recently retired [[Pilgrim]] Nuclear Power Station in Massachusetts, Millstone stands out for its high output and multi-unit configuration. With a total net capacity of over 2,100 MWe, Millstone surpasses Seabrook’s single-unit output of 1,244 MWe, making it a larger contributor to the ISO-NE grid. Its reliability has been consistent in recent years, with scheduled outages managed effectively, similar to Seabrook’s performance. In terms of age, Millstone’s units (commissioned in 1975 and 1986) are comparable to Seabrook (1990), though older than some newer regional energy sources like natural gas plants. Operating costs for nuclear plants like Millstone are generally higher than for gas or renewables due to stringent safety and maintenance requirements, but its carbon-free output provides a competitive edge in meeting clean energy goals. Compared to the decommissioned Pilgrim plant, Millstone benefits from license renewals and modern safety upgrades, positioning it as a long-term asset for New England’s energy mix. Its role as Connecticut’s primary electricity source further enhances its regional significance [NRC.gov](https://www.nrc.gov/info-finder/reactors/mill3). ### Closing Note Millstone Power Station remains a cornerstone of Connecticut’s energy infrastructure, providing critical baseload power to the New England grid with a stable operational outlook through at least 2035. *Report generated December 24, 2025*