The owner of the Pilgrim nuclear power plant in Plymouth, Massachusetts says the facility will be refueled next year, pushing its planned shutdown to May 2019.

New Orleans-based Entergy Corp. announced in October that it would close the state’s only nuclear power plant as soon as spring 2017 and as late as spring 2019.

Entergy’s decision Thursday to refuel next spring pushes the closure to the back end of the original plan.

The Plymouth plant, which began generating electricity in 1972 and was relicensed for 20 years in 2012, generates 680 megawatts of electricity, enough to power more than 600,000 homes.

Entergy cited “poor market conditions, reduced revenues and increased operational costs” in its shutdown decision. Federal inspectors had downgraded the plant’s safety rating to the lowest level.