Jan. 10—WATERFORD — More than a decade before its licenses are set to expire for the two Millstone nuclear stations it owns locally, Dominion Energy has filed a notice with the U.S. Nuclear Regulatory Commission that it intends to seek approval to run the plants for many years to come.

In a letter to the NRC dated Dec. 20, Dominion's vice president of nuclear engineering and fleet support, James E. Holloway, stated that the company, along with partners Green Mountain Power Corp. and Massachusetts Municipal Wholesale Electric Co., plans to apply for a license extension of 20 years for both Millstone 2 and Millstone 3.

The older Millstone 2 plant's license currently runs through July 31, 2035, while the newer Millstone 3's license will not expire until Nov. 25, 2045. The plants currently account for about a third of the town's tax revenue, or about $36 million a year, according to Dominion calculations.

Michael O'Connor, site vice president of Millstone Power Station, said in an email that Dominion's notification to the NRC does not necessarily commit it to running the power stations through the licensure periods, which would extend to 2055 for Millstone 2 and 2065 for Millstone 3.

"Although we have no plans to do so at this time, the plants can be removed from service permanently any time during this period," he said. "Currently, we have no plans to close the plant as long as it is economically feasible to operate it. It is critical for both the New England region and our company."

O'Connor went on to explain that the license-renewal process will include assessments of the plants' key safety systems to ensure the "ongoing viability" of the nuclear plants, which are regularly overhauled and maintained.

"Components needed to safely and reliably generate electricity are in a life cycle management process," he said. "As equipment ages or becomes obsolete it is replaced with new components."

According to the NRC's website, license renewal applications must address a wide range of potential issues, including environmental effects and safety compliance.

"An applicant must address the technical aspects of plant aging and describe how those effects will be managed," the website said. "The NRC will renew a license only if it determines that a currently operating plant will continue to maintain the required level of safety."

O'Connor said the notice to the NRC came early to allow the agency sufficient time to review all the materials about the plant that have to be provided by Dominion in the license-renewal process. No formal license renewal application will be submitted until 2025 at the earliest, he added, and a decision could come as late as 2035.