The Yankee Rowe nuclear reactor, a western Massachusetts plant that is the nation's oldest, began shutting down yesterday a few hours after the staff of the Nuclear Regulatory Commission said it had "reduced confidence" in the plant's safety.
Regulators seldom close an operating plant. The last time it happened was in 1987, when federal inspectors found operators asleep in the control room and other deficiencies at the Peach Bottom plant in southeastern Pennsylvania.
This time, the staff had planned to present its findings to the NRC this morning, but a plant spokesman, William McGee, said that under the circumstances, "it seemed like the prudent thing to do for us to voluntarily initiate the shutdown" rather than wait for a vote.
Operators said they hoped to win permission to reopen the plant soon. But critics of Yankee Rowe, who have been fighting for months to close the plant for precisely the reasons cited yesterday in the NRC staff's findings, said they would try to keep it closed.
The plant supplies about 1 percent of New England's electric power, so the closing will not affect supply or price.
Rowe had intended to apply for renewal of its 40-year operating license last month under a procedure laid out by the NRC this summer, but the plant abandoned that schedule as it became embroiled in a furorover its safety and whether it should be closed immediately as a hazard.
Attention was focused on Rowe's safety in June when a nuclear watchdog group, the Union of Concerned Scientists, petitioned the commission to shut down the plant because of uncertainty about the condition of the reactor pressure vessel. Radiation makes the vessel more brittle every year.
Until yesterday, the NRC's staff had agreed with Rowe's operators that the plant could be safely operated until March, when the owners, a coalition of New England utilities, planned to close it for its most detailed inspection since the plant began operation in 1960.
But yesterday, the chief of the NRC's staff sent a memorandum to the commissioners saying new computer simulations cast additional doubt on the vessel's safety.
The problem, which experts say could become increasingly common among the nation's aging reactors, is whether the vessel is so brittle that it would crack like a glass jar during an accident.
At the plant, a mile south of the Vermont border and 35 miles east of Albany, N.Y., some opponents were ambivalent about the closing.
"I think the NRC staff recommendation that it be closed down is good news," said Gail Steinbring, a member of an activist group, Citizens Awareness Network. "But in reality, we've been living with a risk far greater than we were aware of."