March 21 (Bloomberg) -- U.S. nuclear-power generation dropped for a ninth day, the longest streak of declines since October 2010, as Exelon Corp. unexpectedly shut the 1,136-megawatt Byron 2 reactor in Illinois.
Nationwide production slipped 1.1 percent to 78,213 megawatts, or 77 percent of capacity, the lowest level of output since Nov. 22, according to U.S. Nuclear Regulatory Commission data compiled by Bloomberg. Generation was 2 percent less than a year ago with 22 of 104 nuclear reactors offline.
Byron 2, about 85 miles (137 kilometers) west of Chicago, shut after a loss of generator cooling water caused a manual reactor trip, an event report filed with the NRC showed. The unit had been operating at full capacity.
Exelon is investigating the cause of the malfunction, which occurred on the non-nuclear side of the plant, according to a company statement today. The company didn’t say when the unit is expected to return to service.
The unplanned shutdown sent output in the Midwest, the NRC’s Region 3, to the lowest level since May 2. Generation fell 6.4 percent to 16,675 megawatts.
The only other region to post a decline in production was the West, which slipped 0.1 percent to 16,500 megawatts after Entergy Corp.’s Arkansas Nuclear 1 reactor slowed to 80 percent of capacity from 82 percent yesterday. The 843-megawatt plant is about 65 miles northwest of Little Rock.
Nuclear-power production in the Southeastern region of the U.S., known as Region 2, snapped a 13-day decline after Southern Co. boosted the 883-megawatt Hatch 2 reactor to 47 percent of capacity. The unit, which is about 74 miles west of Savannah, Georgia, and was shut for scheduled refueling since Feb. 11, ran at 18 percent of capacity yesterday, commission data showed.
Southeastern generation advanced by 247 megawatts, while the Northeast added nine megawatts, the data showed.
Reactor maintenance shutdowns, usually undertaken in the U.S. spring or fall when energy use is at its lowest, may increase consumption of natural gas and coal to generate electricity. The average refueling down time was 46 days in 2012, according to the Nuclear Energy Institute.
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