It’s that time of the year again. Back to school sales fill commercials, radio waves, and storefronts as the first half of August fades into the background. It can be hard to accept these reminders that soon students will be crowding school buses as we attempt to soak up the final rays of the summer sun. Even with the last summer BBQs still on the calendar in the coming days, preparation for the fall season is in full swing. Here at EnergyGPS, we want to make sure everyone is prepared for the upcoming energy season. Summer, with its high demand days, isn’t quite in the rearview, but it’s still important to think ahead to shoulder season. In this article, we’ll explore one aspect of shoulder season and what you can expect for this fall’s nuclear outages.

 Just like when students return to school after summer break, we need to go back to the basics. Nuclear plants across the US need to go through routine maintenance and refueling. This scheduled work occurs every 18 months or two years depending on the plant. It’s done during the fall and spring when demand levels tend to be lower, and grids can spare some of the baseload energy nuclear plants provide. For the impacted regions, another energy source, often natural gas, will need to pick up the slack. This means understanding nuclear outages can be a key component when considering the level of power burns to expect this fall.

To get an idea of what’s in store for fall 2024, we can look to previous years to see how high outages typically get. However, we can’t just use last fall’s level of US nuclear outages as a reference point because of the 18 and 24-month cycles. In fact, we must go back 6 years to see the same set of plants go offline for refueling. The visualization below demonstrates the pattern of nuclear outages each fall and spring over the last several years. The green bold font represents the timing of plants that refuel every two years in the fall. They were offline in fall 2020 and fall 2022. The blue boxes represent the plants with 18-month cycles that are offline this fall. These plants were offline in spring 2023 and fall 2021, but not fall 2022 or fall 2020. To get back to the same set of plants, we need to go all the way back to fall 2018 which has both the green font plants and the blue box plants.

Figure 1 | Visualization of Nuclear Outage Patterns