PLYMOUTH — Pilgrim Nuclear Power Station received some good news this week: an unusual occurrence at the 45-year-old problem-plagued reactor.

Federal inspectors, who had scrutinized 24 of the areas where the plant had fallen short, found all 24 had been satisfactorily addressed. The inspection report was based on a visit from a Nuclear Regulatory Commission inspection team in late March.

More important, perhaps, a violation that had helped pitch the plant in 2015 into the lowest performance category contained in federal standards had been adequately addressed, the inspectors reported.

The so-called “white” finding, indicating a problem of moderate significance, was closed and “will no longer be considered in assessing plant performance.”

The violation had involved failure of a safety relief valve needed to help vent steam from the reactor to a cooling pool called a torus.

The valve failed during a storm in 2013. Because valve problems weren’t adequately addressed, another safety relief valve failed in 2015 under similar circumstances.

Closing out the “white” violation is a significant step.

“That was a key area of focus,” NRC spokesman Neil Sheehan said.

Patrick O’Brien, spokesman for Entergy Corp., Pilgrim’s owner and operator, issued a statement saying the company is pleased with the recent inspection results.

“It demonstrates that the Pilgrim team has continued to improve performance at the site,” O’Brien wrote. “As the NRC notes in its letter, there remain three additional inspections, including one that just recently concluded, that we must satisfactorily complete before the NRC can give consideration to moving Pilgrim out of Column 4.”

That may present a challenge.

The series of inspections is part of the increased federal oversight of Pilgrim, based on its Column 4 performance status, one step above mandatory shutdown.

Inspectors check certain areas of a “recovery” plan that has been outlined in a Confirmatory Action Letter and signed by Entergy and the Nuclear Regulatory Commission.

The letter contains 156 items that must be addressed and closed out. “So far they have completed about 25 percent of the 156,” Sheehan said. “We still have 75 percent of the commitments to look at.”

Special inspections will continue if items still remain on Pilgrim’s “to do” list.

The NRC’s letter to Pilgrim managers said NRC staff “will assess the effectiveness of Entergy’s implementation of the corrective actions and evaluate whether the safety performance at Pilgrim has demonstrated sustained improvement warranting a transition out of Column 4,” once commitments in the Confirmatory Action Letter are met.

The agency would then schedule a public meeting in Plymouth to announce its findings.

Pilgrim is set to permanently close by June 1, 2019.

— Follow Christine Legere on Twitter: @ChrisLegereCCT.