Entergy Corp. returned the River Bend 1 and Grand Gulf 1 reactors to full power early today, lifting U.S. nuclear generation to the highest level in more than three months.
Production nationwide gained 0.6 percent from yesterday to 90,373 megawatts, or 89 percent of capacity, the most since Sept. 14, according to U.S. Nuclear Regulatory Commission data compiled by Bloomberg. Output was 3.8 percent less than during the year-earlier period with 11 of 104 reactors offline.
River Bend 1, a 989-megawatt reactor 24 miles (39 kilometers) northwest of Baton Rouge, returned to 100 percent of capacity after slowing yesterday to 50 percent because of a failure to an optical isolator, according to Katie Damratoski, a company spokeswoman based in St. Francisville, Louisiana.
“The cause of the failure is under investigation,” she said. She described the equipment as a “device that is interposed between two systems to prevent one of them from having an undesired effect on the other.”
The 1,297-megawatt Grand Gulf plant operated at full power, up from 96 percent of capacity yesterday. Entergy returned the unit to service after completing a maintenance outage that began Dec. 8, said Suzanne Anderson, a company spokeswoman who is based at the plant.
Work was conducted on the main turbine generator systems, while testing and repairs were also done on several plant components, she said. Grand Gulf is about 25 miles southwest of Vicksburg, Mississippi.
Production in the West, the NRC region that stretches from Washington state to Louisiana, rose 2.6 percent to 19,446 megawatts, the highest since Dec. 8, commission data compiled by Bloomberg show.
The Northeastern region, covering the area from Maryland to Maine, gained 57 megawatts as Constellation Energy Group Inc. boosted output to full capacity at Nine Mile Point 1 near Oswego, New York.
The 621-megawatt unit, which powered up after completing maintenance, operated at 70 percent of capacity yesterday, Jill Lyon, a plant-based spokeswoman, said in an e-mail. Nine Mile Point 1 shut last week after operators saw indications of an air leak from the primary containment wall or drywell, she said.
FitzPatrick 1, a 852-megawatt Entergy unit also in New York, slowed to 50 percent of capacity for maintenance on one of the station’s four main condensor waterboxes, according to Tammy Holden, a company spokeswoman at the plant.
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.