Note: This story first appeared on Duke Energy's storytelling website, illumination.
While nuclear power plants produce low-carbon energy around the clock, every 18 to 24 months the plants shut down for roughly a month for maintenance, inspections and refueling.
Scheduled refueling outages result in greater efficiency and reliability when electricity is needed the most: hot summers and cold winters. That’s why outages occur during spring and fall, when energy demand is lowest.
In 2018, Duke Energy went through a record-breaking eight refueling outages. The company has 11 nuclear reactors at six sites, and each plant had at least one outage. Catawba and Oconee nuclear stations in South Carolina had two.
American nuclear plants provide the most efficient form of generation, producing an average 92 percent of their capacity. For comparison, solar averages 27 percent. In the Carolinas, Duke Energy’s six nuclear plants are a low-carbon energy source providing more than half of the energy delivered to customers.
Check out these videos for a behind-the-scenes look at what happens at the plants:
Video: McGuire Nuclear Station fuel loading
During a refueling outage, about one-third of a reactor’s used nuclear fuel is replaced, as seen in this video. The blue light coming from the reactor is known as the Cherenkov effect, which occurs when electrically charged particles travel through a clear medium like water.
Video: New turbine rotor at Robinson Nuclear Plant
With units temporarily shut down for refueling, planned outages provide nuclear workers the opportunity to replace major equipment. This video shows a new rotor – the part of a turbine that spins – being lifted into place.