Waterford — While Millstone Power Station will remain open for at least another decade following a deal announced by Gov. Ned Lamont last month, the U.S. Nuclear Regulatory Commission is reviewing the status of decommissioning funds for the nuclear plant's two operating units.

Millstone owner Dominion Energy recently filed an update on decommissioning funds as part of required biennial reporting to the NRC. As of Dec. 31, 2018, more than $1.37 billion — $672.5 million for Unit 2 and $704.8 million for Unit 3 — was held in external trusts to carry out future decommissioning of the units. The combined funds exceed NRC minimum requirements by almost $404 million, according to Dominion's report.

"The NRC will carefully review the submittal to ensure there is sufficient funding to carry out the decommissioning of the plants," NRC spokesman Neil Sheehan said Thursday. Sheehan noted that plant owners must submit updates on decommission funding every two years, while "plants that are within five years of permanent shutdown might submit updates on an annual basis."

While Millstone Unit 1 permanently ceased operations in 1998, Unit 2's operating license with the NRC is active until 2035, and Unit 3's license expires in 2045.

Millstone Unit 1 is undergoing what the NRC classifies as the SAFSTOR method of decommissioning, whereby a nuclear plant is maintained in a condition that allows it to be safely stored and monitored for several years before it is eventually decontaminated to levels that would allow unrestricted use of the site. The time limit for the SAFSTOR process is 60 years, which allows the radioactivity of materials to decrease over time.

"Dominion Energy believes that the amounts (of funds) currently available in the decommissioning trusts and their expected earnings will be sufficient to cover expected decommissioning costs for Millstone," plant spokesman Ken Holt said Thursday.

For all three units combined, about $1.85 billion is held in trust for decommissioning, with an expected total cost of approximately $1.7 billion in 2018 dollars, Holt said.

Holt said he did not have a breakdown of environmental cleanup and demolition costs involved in the decommissioning process but noted that because Units 1 and 2 were constructed so close together, waiting until Unit 2 "shuts down permanently will make demolition of both easier."

According to Dominion, there have been no changes to trust agreements established for nuclear decommissioning since the previous report to the NRC on March 30, 2017.

b.kail@theday.com