The findings could determine what steps the owners must take as they prepare to wind down operations at the 43-year-old plant. Entergy Corp., which bought Pilgrim in 1999, has said it plans to refuel the facility a final time next year.

The Nuclear Regulatory Commission will conduct a three-week review of the facility’s physical state and staff performance, an intensive evaluation brought on by a downgrade to Pilgrim’s safety rating last year.

Federal regulators on Monday will begin a high-stakes inspection of Pilgrim Nuclear Power Station in Plymouth, dispatching a team of 20 people to the troubled plant as they seek to ensure that it has a plan to produce power safely before its scheduled closure in 2019.


The company called the inspection “the next step in Pilgrim’s process toward a return to industry excellence.”

“We have worked hard to address the issues that led to station performance decline and look forward to demonstrating to the NRC that we have made significant progress in these areas through the inspection process,” Entergy spokesman Patrick O’Brien said in a statement.

Only two other reactors — both in Arkansas — have safety ratings as low as Pilgrim, which has been cited for repeated incidents in which it had to shut down without warning.

Officials say that while none of those issues put the public at serious risk, they raised concerns that were significant enough to warrant stricter oversight. If the plant were downgraded any further, federal regulators could order it to close sooner than expected.

“There’s always the possibility that we could find areas of concern that could lead to a change in our posture when it comes to the plant,” said Neil Sheehan, an NRC spokesman.

Pilgrim officials are seeking to convince regulators that they have a solid plan to improve safety. Entergy has said the plant is losing about $40 million a year, and that bringing it into compliance with federal safety requirements would cost tens of millions of dollars.


Critics of the nuclear facility are hoping to see regulators come down hard on the plant, which they say has a history of neglecting maintenance issues.

US Senator Edward Markey, who has been outspoken about his concerns over Pilgrim, called on the NRC to “scrub Pilgrim from top to bottom.”

“I have serious concerns that both Entergy and the NRC cannot be trusted when it comes to Pilgrim’s safety,” he said.

Markey cited a recent NRC report that found that Entergy had not replaced aging electrical equipment to help contain radiation in an emergency, leaving some components in place for more than three times their recommended 10-year lifespan.

The NRC said those violations were not serious, but opponents said they represent a troubling trend.

“Many of these problems have a common thread, in that Entergy has been following a policy of not fixing anything until it breaks,” said Mary Lampert of the watchdog group PilgrimWatch.

The plant, which employs more than 600 people, will be closely monitored after it stops making power, as workers handle spent nuclear material stored on the site.

The Massachusetts Emergency Management Agency will send a representative to observe the inspection. Lampert had urged the state to send a nuclear engineer to play a more active part, but the agency said that was not its proper role.


The inspection comes as state and regional officials make plans to do without the 680 megawatts of power produced by the plant, enough for more than 600,000 homes.

The energy is carbon-free, a major boost to the state’s efforts to reduce greenhouse emissions.

Greg Cunningham, director of the Conservation Law Foundation’s energy and climate change program, said he is confident the state is making the necessary adjustments to offset Pilgrim’s closure.

“Certainly it makes the job harder and it requires further measures, but these are all things that are being weighed and contemplated and designed as we speak,” he said.

Andy Rosen can be reached at andrew.rosen@globe.com. Follow him on Twitter @andyrosen.