Waterford — A major inspection of Units 2 and 3 at the Millstone Power Station resulted in one finding of a safety problem of very low significance, the Nuclear Regulatory Commission announced Wednesday.

The three-week inspection, completed May 11, brought a team of seven NRC officials to the two units to examine areas related to the adequacy of various engineering components of the nuclear power plants, along with procedures, calculations of systems, records and conduct interviews with personnel, among other areas.

This level of inspection takes place every three years as a condition of the power station’s operating license. It is one of the most intensive of all the regular NRC reviews nuclear power plants undergo, said Neil Sheehan, NRC spokesman. The main purpose is to ensure that systems and components are being operated consistent with their design, he said.

The single finding was determined by the NRC to be of “very low safety significance,” but was considered “more than minor” because it involved a main objective of ensuring that systems that are intended to work in the case of accidents or other emergencies are verified as reliable, the NRC said.

The finding involved verification of the design of a control circuit in Unit 2 that would be used for power switching in the event of an emergency, Ken Holt, spokesman for Millstone owner Dominion, said. NRC inspectors found that the calculations that would verify that it would perform correctly in a safety event had not been done, Holt said. The calculations are now being done, he added.

The NRC said the problem did not result in a loss of operability or functionality of the system.

“This is one of the largest inspections, and obviously we would have preferred that the NRC had no findings, but we are pleased that the one they did find was of very low safety significance, and we’re working on corrective actions,” he said.

Sheehan said most NRC inspections of this type result in one to three findings.

The NRC will conduct a follow-up inspection will be conducted in the coming weeks to verify that the corrections have been made.

j.benson@theday.com