PLYMOUTH, Mass. — The Pilgrim nuclear power plant in Plymouth has permanently shut down after 47 years of generating electricity, bring to a close the era of nuclear power in Massachusetts.
The final shutdown occurred at 5:28 p.m. Friday.
Entergy announced in 2015 it would retire Massachusetts’ only remaining reactor, citing competition from less expensive energy sources.
Entergy had said the shutdown would take about five hours, with technicians first reducing Pilgrim’s power output from the 40 percent to 26 percent to about 8 percent, before launching the final step of inserting control rods into the fuel assembly to seal off further nuclear reactions.
The focus now turns to the daunting task of cleaning up and dismantling the plant. The Nuclear Regulatory Commission is reviewing Entergy’s proposal to sell Pilgrim to a private nuclear waste management firm that promises a speedier decommissioning.
The closing leaves Seabrook in New Hampshire and Millstone in Connecticut as New England’s only operational commercial nuclear plants.
Pilgrim’s retirement and the loss of its 680 megawatts of power aren’t likely to disrupt overall regional energy supplies or the reliability of the electrical grid, according to experts.
ISO-New England, which operates the region’s bulk power system, says three new power plants that can burn either natural gas or oil will be online by this summer and several small solar facilities and a new wind farm will also help absorb the impact.
“We’ve actually seen more megawatts coming in than the megawatts of Pilgrim that are leaving,” said Anne George, a vice president for ISO.
The shutdown could result in a short-term increase in carbon emissions because of the greater reliance on the gas and oil-burning plants, she said, though longer range trends point to growth in cleaner, renewable energy sources.
It’s unclear whether Pilgrim’s closing could affect consumer prices. George noted that nuclear power generally enters the electricity market at lower prices than most other fuels.
What happens next? It’s far from certain how decommissioning will unfold.
Entergy announced plans last year to sell Pilgrim, along with several other retiring U.S. reactors, to Holtec International for decommissioning. The deals are awaiting NRC approval.