Optimizing U.S. Nuclear Refueling Outages for Efficiency
U.S. Nuclear Power Plants Optimize Safety and Efficiency During Refueling Outages
U.S. nuclear power plants typically undergo refueling outages every 18 to 24 months, with these maintenance periods typically taking place in the spring and fall when electricity demand is at its lowest. The Energy Information Administration (EIA) tracks U.S. nuclear plant outages and updates a webpage daily with data provided by the Nuclear Regulatory Commission (NRC). From 2018 through 2023, spring outages peaked in mid-April with an average capacity of about 15 GW to slightly more than 23 GW out of service. Fall outages follow a similar pattern, peaking in late October with a comparable amount of capacity offline for maintenance and refueling.
During refueling outages, plants take the opportunity to schedule facility upgrades, repairs, and other maintenance work while the nuclear reactor is offline. In recent years, the average duration of refueling outages has been around 32 days, a significant improvement from the more than 80 days it took back in 1997. This progress has been attributed to a focus on continuous improvement within the industry.
The fuel for nuclear plants involves ceramic pellets of uranium that go into metal tubes and form fuel rods. Cranes can grab bundled rods and move them around. During a refueling, the oldest one-third or so of the fuel is shifted to a used fuel pool, and new bundles are added. Refuelings for a given U.S. reactor typically occur every 18 or 24 months.
The Electric Power Research Institute (EPRI) has played a significant role in optimizing outage planning techniques with the issuance of their technical report titled “Effective Refueling Outage Preparation and Execution Guidance” in 1993. This report has been updated periodically to reflect evolving industry practices and technological advancements, with the most recent version released in November 2022.
EPRI’s ChemWorks Tools, including the shutdown calculator (SDC) tool, have provided valuable assistance in outage planning. A recent study by researchers from Korea Hydro and Nuclear Power’s Central Research Institute utilized the SDC tool to model shutdown chemistry evolution and predict cleanup times in pressurized water reactors (PWRs). Their findings, published in Nuclear Engineering and Technology, highlighted the tool’s ability to accurately estimate cleanup time and improve the efficiency and safety of shutdown chemistry evolutions in nuclear power plants.
The ongoing effort to ensure excellence in nuclear refueling outage safety, performance, and cost management is crucial for the industry. With the assistance of tools and guidance from organizations like EPRI, nuclear power plants are able to optimize outage schedules, minimize downtime, enhance safety measures, and improve overall efficiency during the refueling process.
Overall, the industry’s dedication to continuous improvement and adherence to best practices has led to significant advancements in the efficiency and safety of U.S. nuclear power plants during refueling outages. By incorporating the latest technologies and guidance, these plants are able to ensure the reliable and sustainable production of electricity for years to come.