Ameren Missouri Callaway Energy Center employees wore white protective suits and goggles as they stood on a bright yellow refueling machine at the nuclear facility Monday afternoon. They continued to add fuel assemblies back into the plant's reactor core.
The nuclear power plant started a planned refueling and maintenance outage on Oct. 11. Callaway Energy Center officials expect the plant to wrap up its maintenance projects and refueling later this month.
The 1,190-megawatt facility has refueling outages every 18 months. The plant is replacing 84 of its 193 fuel assemblies in the reactor core during its current outage. During each refueling outage, about one third of the fuel assemblies are transferred to the plant's spent fuel pool and that same number of new fuel assemblies are added back to the reactor.
While replacing the fuel assembles, Senior Director of Nuclear Operations Barry Cox said the plant keeps them under about 28 feet of water. The water helps keep the fuel assemblies cool and further protects the personnel at the plant who work to replace them.
The fuel assemblies are enclosed in the containment building on the plant's property. The dome-shaped building sits on 10-foot-thick floor and has 4-foot-thick walls. Inside the building is the nuclear facility's reactor vessel.
Another major project for the plant's 20th planned outage has been replacing the original reactor vessel head that was installed when the plant went online in 1984. Cox described the new reactor vessel head - a $150 million piece of equipment - as a key component to extending the life of the Callaway plant, which is waiting to hear the Nuclear Regulatory Commission's decision on its license renewal.
The plant's operating license is set to expire in 2024. The NRC will decide to accept or deny the plant's request to extend its
operating license to 2044. As part of the license renewal process, the plant evaluated equipment to determine how much longer the equipment will last before needing to be replaced.
The new reactor head was produced in Spain over a three year period. Then, it was shipped to New Orleans and transported to the Callaway Energy Center's Missouri River dock in late May. The plant contracted a company to use a crane to lift the 288,170 pound reactor vessel head up to the top of the containment building.
As part of its maintenance during this planned outage, the plant also performed an integrated leak rate test - a test it does every 10-15 years. For that test, the plant pressurized the containment, or reactor, building to 48 pounds.
"We pressurized that (the reactor building) to about 48 pounds and held it to make sure that it would hold pressure at 48 pounds for a specified period of time. That way, we can guarantee that there is no leakage," Cox said.
The plant's 800 employees have had the help of more than 1,100 additional workers during its current outage. The plant has and will continue to perform various other tests and safety inspections during the outage.
The Callaway plant produces about 20 percent of the electricity for Ameren Missouri's 1.2 million customers. Customers' service was not affected by the planned outage.