Waterford — Violations of safety equipment requirements at Unit 3 of the Millstone Power Station have led to increased oversight by the Nuclear Regulatory Commission.

The NRC announced Tuesday that it has finalized a “white” finding for plant owner Dominion’s failure to promptly identify and correct repeated problems involving a feedwater pump that is part of the reactor safety system. NRC spokesman Neil Sheehan said the “white” finding, of “low to moderate” safety significance, the second-lowest on a four-tier scale of violations, will be in effect until June 30. The NRC began increased oversight of Unit 3 last June 30 when it issued a preliminary “white” finding.

Along with the “white” finding, the NRC also confirmed Tuesday that it has begun a special inspection related to security at Millstone.

“We can confirm that we have a security review under way at Millstone,” Sheehan said. “However, we can’t provide details.”

He said if the inspection results in findings that are greater than “green,” the lowest level of safety significance, the public and the media would be notified.

Millstone spokesman Ken Holt said he could not comment on the security inspection.

The violation involving the feedwater pump was found after NRC inspectors determined that from May 2013 to February 2014, Unit 3’s backup feedwater pump was operating improperly because of an incorrect bearing. The bearing, which had been mislabeled by the manufacturer, caused two unexpected fluctuations in cooling water flow to the reactor and three shutdowns of the pump. The backup pump is one of several pumps at the plant that can be used to draw in water after a shutdown to cool the reactor in an emergency. Although Dominion has repaired the pump and completed a root-cause evaluation, the NRC said it is taking enforcement actions because of the length of time the company took to address the problem.

“Our inspectors have carefully documented multiple problems involving this pump that occurred over the course of many months,” David Lew, acting NRC regional administrator for Region 1, said in a news release. “What concerns the NRC is that despite repeated efforts to repair this important component, the problems persisted and called into question the pump’s past reliability.”

The NRC did not levy a fine for the violation but will require the company to pay for the cost of the additional inspections.

Holt said the last time there was a “white” finding at Millstone was in February of 2011. Unit 3 is currently shut down for refueling, and the company is using this time to do additional testing and maintenance on the feedwater pumps, he said.

In addition to the increased oversight, the NRC also will conduct an additional inspection on the corrective actions plant workers undertook to fix the problems with the pump, Holt said.

Sheehan noted that the NRC also has begun a separate special inspection relating to different problems with the same pump. That inspection began in September, and once completed, an inspection report will be issued within 45 days.

The NRC issues about a dozen findings of “white” or higher levels annually for the 99 operating reactors nationwide. A “white” finding, Sheehan said, “is not an ordinary development.”

Bill Sheehan, chairman of the Nuclear Energy Advisory Council, said the NRC’s action finalizing the white finding was expected. The council, a citizens’ panel that oversees safety-related issues at Millstone, last month expressed concerns about safety issues at the plant that have come to light in three recent special inspections by the NRC. In addition to the two special inspections of the pump, the NRC also initiated an inspection in May of the plant’s power line outage detection system. The inspection followed an unplanned shutdown of Units 2 and 3 due to an outage in electricity lines that service the plant. The NRC issued a “severity level 3” violation for that system, determining that plant staff could have taken steps to avoid the sequence of events that led to both plants going offline.

On Tuesday, Bill Sheehan, who is not related to the NRC spokesman, said he remains concerned.

“What a white finding means is that performance has slipped, and that’s disturbing,” he said.

Dominion, he said, has not responded to the issues raised by council members at its Sept. 18 meeting, which was the annual presentation by Millstone representatives of the events of the past year at the plant.

“Having one (special inspection) is disturbing, but having two others shows a performance deterioration,” he said. “I hope they can figure out why and correct this.”

j.benson@theday.com

Twitter: @BensonJudy