Outages during U.S. chief energy plants were intensely low this summer (June by August), averaging 2.9 gigawatts (GW), or reduction than 3% of sum U.S. chief capacity. During 4 days in August, outages forsaken to usually 0.1 GW out of a sum U.S. chief ability of 98.7 GW, a lowest value available given a U.S. Nuclear Regulatory Commission (NRC) began collecting information in 2007.
Nuclear energy plants yield baseload electricity era and do not change outlay in response to daily or hourly fluctuations in electricity demand, as do energy plants using on other fuels, such as healthy gas. In June, chief energy accounted for scarcely 20% of sum U.S. electricity generation. Although chief plant outages are typically low during a summer and winter months, when electricity direct is comparatively high, outages this year have been most reduce than normal. The diminution in chief energy plant outages, both designed and unplanned, might be attributable to several factors.
Shorter refueling-related outages. Nuclear reactors typically refuel each 18 to 24 months. Although a reactor can be fueled in as small as 10 days, refueling-related outages mostly final longer, as operators report other noncritical upkeep work during a same time to minimize downtime.
The normal era of chief energy plant refueling outages has been usually declining. In a early 1990s, refueling-related outages lasted about 3 months. More recently, these outages lasted 6 weeks.
Fewer uprates. Uprates to chief reactors, in that a energy plant increases a limit generating capacity, generally engage physically modifying a energy plant and need a plant to be offline. Large or extended uprates might even be implemented over a march of dual refueling outages.
In early 2013, 5 reactors finished extended energy uprates totaling some-more than 600 megawatts (MW), that compulsory extensive outages. In contrast, uprates now underneath examination and tentative capitulation by a NRC sum usually 61 MW, and a NRC expects to accept additional requests for a sum of usually 580 MW between 2015 and 2019, out of a sum ability of 98.7 GW.
Improved handling performance. U.S. chief energy plant opening and trustworthiness have consistently softened over a past 10 years. In 2014, a chief swift operated during an normal annual ability factor—the magnitude of a capability of a energy plant to sojourn online and beget electricity—of 91.7%. The chief fleet’s normal estimated monthly ability cause for Aug 2015 was 98.4%, compared with 96.4% for Aug 2014. According to a Nuclear Energy Institute, 95 of 99 handling reactors achieved a ability cause of 90% or aloft during August, and 48 of a nation’s 99 handling chief reactors achieved a ability cause of 100% or above—reported ability factors somewhat above 100% are probable since they are formed on net summer capacity, that can be reduce than tangible limit era capacity. Unplanned involuntary or primer reactor shutdowns also reached a record low of 59 shutdowns in 2014.
Continued potency improvements will digest outages of chief energy plants. However, as summer transitions to fall, outages are approaching to boost from their ancestral lows as chief plants enter a tumble refueling and upkeep season. Outages can be tracked on EIA’s Status of U.S. Nuclear Outages website.