In the electric utility industry, “outage” can be an unwelcome word. However, for nuclear plants, scheduled refueling outages mean greater efficiency and reliability. While nuclear plants produce carbon-free energy around the clock, every 18 to 24 months the plants shut down for maintenance, inspections and refueling, at which time workers replace about one-third of the used fuel assemblies with new ones. These focused outages make nuclear plants even more efficient because they offer workers the opportunity to perform maintenance that would be more difficult if the plant was online. By conducting inspections and performing maintenance at the same time as refueling, workers can eliminate the need to power down the plant at other times to perform the same work. This allows nuclear plants to produce electricity continuously for months and even years at a time – a feature no other electricity source provides.
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. Typical refueling outage duration for U.S. nuclear plants is 25 days, among the shortest average in recent decades.
Even though outage duration has gotten shorter over the years, safety and quality work remain top priority. There are typically about 9,000 work activities that go on, which on average is about 343 activities completed each day of an outage. Sounds like a lot to do in a short amount of time! Each Duke Energy-operated nuclear site has a highly-skilled outage scheduling team that helps keep everyone on pace by managing schedules and work scope, all while keeping workers safe.
We recently met with Brittany Hansen, senior Work Management specialist at McGuire Nuclear Station in Huntersville, N.C. She shared some interesting things about the outage management team she works with at the two-unit nuclear site. We’re sharing our top five with you:
The refueling outage management team begins preparing for an outage about three years in advance of the actual outage start date. There typically is a list of milestone activities governed by a procedure that dictates the scope of work and work tasks. The main body of work begins about 12 months from the outage start when the outage scope is developed – that’s when the actual outage schedule is created and reviewed by different groups to ensure the outage can be conducted in the most efficient manner.
The outage management team works full-time focusing their efforts on the upcoming refueling outage from 10-months out through the completion of the outage. An individual in the outage management team contributes about 2,000 hours preparing for a refueling outage. For the whole team, that’s over 14,000 man-hours. As one outage ends, planning for the next outage begins.
The outage management group is made up of eight teammates, each with a specific focus area for scheduling outage work. Work is divided by one of three nuclear systems – primary, secondary and electrical. One team member is the reactor building coordinator – managing work within the containment building like moving equipment in and out of the building. Along with schedulers within the group, the team works alongside three maintenance coordinators who are also separated by discipline. Their role is to position maintenance work at times and dates within the outage schedule to optimize crew performance.
There’s a lot to consider when it comes to choosing what work takes priority. In addition to required refueling tasks, the team looks at preventive maintenance and inspections that must occur on a certain frequency. They also determine which equipment may need to be upgraded or repaired, which ideally can only be done when a unit is shut down. Budget, including overall labor and material cost is, also part of the equation. Outage work scope is then determined based on all of these factors.
When it comes to developing the outage schedule, engagement is essential. It takes multiple departments to provide input when it comes to scheduling to ensure our nuclear plants can return to service safely. The outage management group collaborates with every group at their respective nuclear site to ensure the schedule is accurate and achievable before the outage begins.