U.S. nuclear generation fell to the lowest level in four days as Entergy Corp. shut a reactor in Massachusetts after recirculation pumps tripped offline.
Total U.S. production declined 0.6 percent from yesterday to 92,923 megawatts, or 91 percent of capacity, according to U.S. Nuclear Regulatory Commission data compiled by Bloomberg. Output was 2.5 percent less than a year earlier with eight of 104 reactors offline.
Entergy shut the 685-megawatt Pilgrim 1 reactor yesterday after operating it at full power. The cause of the pump trip at the unit, 38 miles (61 kilometers) southeast of Boston, is being investigated, the company said.
“The plant will be restarted after a thorough evaluation and any necessary repairs are completed,” Entergy said in an e-mailed statement.
Generation in the Northeast dropped 2.8 percent to 24,214 megawatts, the biggest slide since Dec. 16. Western output increased by 130 megawatts as Entergy boosted generation at the Grand Gulf 1 reactor in Mississippi to 90 percent from 80 percent yesterday. The unit tripped offline last week when a protective relay identified a fault, said Mike Bowling, a company spokesman based in Jackson.
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 43 days in 2011, according to the Nuclear Energy Institute.