Callaway Nuclear Plant Returns to Service Following Record-Setting Refueling and Maintenance

The outage duration of 63 days and 13 hours set a new world record for the shortest time it took to conduct an outage that included replacement of four steam generators - the giant "boilers" that produce steam for generating electricity. The previous record was 64 days and 17 hours, set by the South Texas Project in October 2002.

Refueling outages at the 1,147-megawatt plant occur approximately every 18 months, and this was the plant's 14th refueling since it began operating in 1984.

As in past refueling outages, thousands of maintenance activities, modifications, inspections and tests were performed throughout the plant. About 3,000 people worked on the project, including more than 2,000 contractors and Ameren employees from other locations who joined the plant's regular staff to help handle the large volume of work.

Replacement of the plant's four steam generators was the biggest job due to their huge size. Measuring 70 feet tall and 17 feet in diameter at their widest part, and weighing 400 tons each, the new steam generators feature the latest technology for efficiency and reliability.

Another major upgrade performed during the outage involved replacing all four turbine rotors with new, more-efficient models. Each turbine rotor is 35 feet long. Three are 15 feet wide and weigh 164 tons, while the other is eight feet wide and weighs 70 tons. The rotors spin by steam pressure to turn an electric generator and produce electricity.

Like the replacement steam generators, the new turbine rotors are designed to provide increased efficiency and durability compared to the original units manufactured in the 1970s.

The refueling, itself, involved replacing 88 of the 193 fuel assemblies in the reactor core. A fuel assembly is an 8 1/2-inch- square bundle of 12-foot- long metal tubes containing ceramic pellets of uranium dioxide fuel. Each fuel pellet is about the size of a pencil eraser.

Used fuel assemblies removed from the reactor will be stored temporarily in the spent fuel pool - a stainless steel-lined water pool inside the fuel building. The pool - about the size of a tennis court - has enough space to safely store all the used fuel that accumulates at the plant until 2020, with the capability for additional storage capacity through 2024 when the plant's current operating license expires.

Eventually, AmerenUE plans to ship the used fuel to a permanent disposal facility licensed by the U.S. Nuclear Regulatory Commission. In early 2002, Congress and the president approved Yucca Mountain, Nev., as the site for this facility, and the U.S. Department of Energy is currently preparing a license application.

The Callaway Plant generates enough electricity to power 830,000 average homes. While the plant was out of service, its generation was replaced by other plants.