The U.S. nuclear power industry’s 99 operating power generation facilities operated with a capacity factor of 96.4 percent in June, according to a Nuclear Energy Institute report.  It is the highest number in the past six years.

The figure compares to 95.4 percent last June, and is 7 percent higher than the 89.2 percent performance achieved in June 2012.

Capacity factor compares the amount of electricity a power plant produces over a given period to the maximum it could produce at continuous full power operation during the same period. Reactors running at 100 percent capacity, for example, are operating nonstop and at full power over the period measured.

This year the spring refueling outages were quicker than last, averaging 34 days compared to 39 days in the spring of 2014.

“The top generating US nuclear units in 2014 were, Arizona Public Service’s 1,405-MW Palo Verde-3, producing 12.2 million MWh and posting an annual capacity factor of 97.5 percent. STP Nuclear Operating Company’s 1,312-MW South Texas-2, generating 12.19 million MWh and obtaining the highest capacity factor in the analysis globally, over 100 percent,” said the NEI.