Nooter Construction Company designed a plan to replace the condenser tubing, in the circulating water system, at the Callaway Nuclear Generating Station. They implemented the plan by utilizing large on- site prefabricated “supermodule” tube bundle assemblies. This was the first ever supermodule replacement completed safely.
About 400 people worked on the site at the project’s peak. Crews worked two 12 hour shifts, seven days per week. Despite the heavy work schedules, safety remained a top priority for both NCC and Ameren. Nooter began assembling the new tubes into supermodules outside the plant’s secure area about six months before the planned outage.
The condensers have three pressure levels—HP, IP, and LP. For each pressure level, there were six bundles. NCC replaced the six original bundles with a four bundle arrangement, and the two bottom bundles were significantly larger than those coming out. Crews assembled the bundles with weld pipe bracing between the baffles. The supermodules were 56 feet long, 30 feet high and 25 feet wide and were assembled atop three fixtures. About 6 feet of vertical space existed under the modules, which allowed access for a hydraulic deck transport trailer.
Before NCC could begin removing the existing tube bundles, crews had to reinforce the condenser walls to shore up the feedwater heaters located above the condensers. The original tube bundles provided the interior structural support for condensers and the exchangers, which weigh approximately a half million pounds. NCC transported the supermodules, weighing about 500 tons each, into the plant on a track system. As each old tubing section came out, crews drove the transporter under one of the new supermodules and moved it into the plant.
It followed with three modules installed during a three day period beginning May 4, 2004.
NCC completed the entire condenser change out within 44 days. Shannon Able, AmerenUE project manager said, “NCC did an outstanding job with the project. We had a limited design going in, and NCC took what we had and built a good plan and schedule. I was impressed with their on-site management team and they had good control on the job all the way.”