Using a new technique called "virtual alignment," Siemens Generation Services (SGS) and Southern States Millwright Regional Council (SSMRC) millwrights replaced 40-year-old machinery during a spring 2021 upgrade of Unit 1 at Farley Nuclear Station near Dothan, Alabama. The team completed the project -- which increased the plant's output by more than 26 megawatts and improved its reliability -- 100 hours ahead of schedule.
The overhaul included installing a new high-pressure rotor, guide blade carriers and blade rings; retrofitting a steam generator feed pump with new components; and replacing several valves.
"Reducing duration by four days -- that's massive," said Jason Guggisberg, district service manager for Siemens. "That's a significant amount of revenue for Plant Farley and Siemens. And it's a direct result of feedback from craft and implementation of lessons learned."
In fall of 2020, SGS and millwrights from the SSMRC upgraded Unit 2 of Alabama Power's dual-unit Plant Farley. Millwrights cataloged "lessons learned" from the Unit 2 project, and the team drew on this knowledge during the Unit 1 project.
Adaptations
"A lot of issues we faced with the fall outage were anticipated and dealt with preemptively with the spring outage," said Shane Harris, millwright craft labor supervisor.
Sarah Wilson, a journeyman member of Millwright Local 1263 who worked on both the fall and spring outages, said there was a learning curve with the rigging involved in removing the old equipment. In order for the new components to fit properly, a lot of machining activities had to take place in the lower half of the cylinder, Harris said, and some of the hole alignments were off during the fall project. All these challenges and solutions were recorded.
"We saw what could be expected for the other unit," Wilson explained.
That made the second project go smoother and faster. "This time, as soon as a component came in, we verified it and performed the machining," Harris said.
Virtual alignment
Millwrights install the new high-pressure rotor.
A new computer-modeling method also helped reduce outage duration and customer risks. "We make 3-D scans of our parts, assemble them in virtual space, and then decide what machining is required to assemble a machine one time versus putting it together and taking it apart several times," Guggisberg said. "It's really cool."
SGS used the same technique with the fall outage and improved it in the spring based on feedback from millwrights and other craftspeople.
"We were able to enhance the process and, as a result, our performance during the outage," Guggisberg said.
Logistics and manpower
The SGS team was composed of 90 craftspeople, including 47 millwrights as well as pipefitters, laborers, boilermakers, operating engineers and two carpenters.
Anna Rademakers, manager of nuclear service for SGS, said working with David Bonds, nuclear representative for the SSMRC, to fill the millwright positions was "seamless." Because the SSMRC has one point person for nuclear projects, she does not have to coordinate efforts with multiple business agents.
"David knows what we need and who we need," Rademakers said. "We get all the information as far as the scope and the manpower counts, and it's basically a well-oiled team. We also do the background screening for the Plant Farley site, so we have a very streamlined process. No one is sitting around being unproductive. When folks come in, they're doing their training, getting badged and on the deck."
For more information about the Southern States Millwright Regional Council, visit their website or call (855) 577-7672.
