U.S. nuclear power generation fell for a fourth day as Constellation Energy Group Inc. shut the smaller of two reactors at the Nine Mile Point Nuclear Station in New York.
Production dropped 0.2 percent to 89,100 megawatts, or 87 percent of capacity, according to Nuclear Regulatory Commission data compiled by Bloomberg. Output was 5.5 percent lower than a year earlier, with 12 of 104 U.S. reactors offline.
Constellation halted the 621-megawatt Nine Mile Point 1, located 6 miles (10 kilometers) northeast of Oswego, after operators noticed signs of air leakage from the unit’s drywell, part of its primary containment system.
The unit ran at full capacity yesterday but began to shut down around 4:45 p.m. yesterday and was taken off the grid by 7:10 p.m. The plant is stable and poses no risk to the public or employees, said Jill Lyon, a Constellation spokeswoman based in Scriba, New York.
“This was an orderly shutdown of the unit and did not meet any of the criteria for an emergency classification,” Lyon said in an e-mail.
The Tennessee Valley Authority’s Browns Ferry 2, a 1,104-megawatt reactor 84 miles north of Birmingham, Alabama, boosted output to 98 percent of capacity from 48 percent yesterday.
LaSalle 2, Exelon Corp.’s 1,120-megawatt reactor 70 miles southwest of Chicago, declined to 80 percent of capacity from 98 percent.
Nebraska Public Power District’s Cooper 1 unit boosted output to 100 percent of its 830-megawatt capacity and Pacific Gas & Electric Co.’s 1,149-megawatt Diablo Canyon 2 lowered output to 65 percent of capacity.
Reactor maintenance shutdowns, usually undertaken in the U.S. spring or fall when energy use is lowest, may increase consumption of natural gas and coal to generate electricity. The average refueling down time was 43 days in 2011, according to the Nuclear Energy Institute.