Capacity factor is a measure of reliability, and reliability delivers results. The U.S. nuclear power fleet produced about 789.9 TWh of clean electricity in 2020 and ended the year with 94 operating reactors. According to Energy Information Administration data, that’s about 37 percent more electricity than the 576.9 TWh produced in 1990 by a much larger fleet of 112 reactors.
Nuclear News has tracked and analyzed the capacity factors of the U.S. fleet since the early 1980s, before concerted industry efforts yielded unforeseen performance improvements. High nuclear capacity factors are now less an achievement than an expectation. So much so, in fact, that advanced reactors in development today are assumed to be capable of achieving capacity factors above 90 or even 95 percent.
The U.S. fleet has maintained a median capacity factor near 90 percent for 20 years (see Fig. 1), and the median design electrical rating (DER) net capacity factor for 2018–2020, at 91.33, does not disappoint—unless by showing virtually no change relative to the median of 91.34 recorded in 2015–2017. However, this lack of meaningful difference only underscores the consistent reliability of the U.S. fleet.