GE Hitachi Nuclear Energy (GEH), in coordination with Exelon Generation, unveiled a new, innovative remotely-operated tool that has successfully enabled nuclear technicians to complete tasks at the bottom of nuclear reactors more quickly and safely.
This new tool remotely disconnects – uncouples - control rods (one of the pieces of equipment that allows operators to control power production) from their associated blades at the bottom of the reactor during preventative maintenance. Utilizing the battery-powered, wireless device minimizes the amount of radiation that workers are exposed to and allows parallel work activities to take place under the reactor pressure vessel during service outages. The tool has been shown to reduce radiation dose associated with uncoupling by as much as 60 percent.
“The remote uncoupling tool is unique in the industry and another example of our singular ability to develop solutions to some of our customers’ most challenging issues,” said Kevin Walsh, GEH Senior Vice President, Nuclear Services and Fuels. “It is also an important illustration of our use of 3-D printing technologies, speeding our time to market by months and eliminating the significant expense of fabricating metallic mock ups.”
The tool, based on 3-D printed prototypes created on-site at GEH’s world headquarters in Wilmington, N.C., has been successfully deployed during recent maintenance work at the Dresden Generating Station in Morris, Ill. and the Peach Bottom Atomic Power Station in Delta, Pa. A total of 19 drives were uncoupled with the tool at Peach Bottom and 25 were uncoupled at Dresden. The plants are operated by Exelon Generation which operates the largest nuclear fleet in the U.S.
“Safety is at the forefront of everything we do,” said Exelon’s Senior Vice President Dave Rhodes, who oversees refueling activities across the 14 nuclear plants Exelon operates. “We are pleased to have worked with GE Hitachi on a tool that adds another layer of safety to our work process.”
Control rod blades are long, cruciform metal-tube components that contain neutron-absorbing material and are positioned adjacent to nuclear fuel assemblies within the reactor core. Operators remotely adjust the position of these blades to manage power generation.
In order to remove control rod blades during service outages the blades must be uncoupled from drive mechanisms underneath the reactor pressure vessel. Any blades that are not successfully uncoupled from underneath the vessel must be uncoupled from a refueling floor above the vessel, a more time consuming process.
Because of the tool’s effectiveness it was not necessary to conduct any uncoupling from the refueling floor during the Dresden and Peach Bottom outages. This new tool replaces a much more labor-intensive process involving floor jacks and the removal of large quantities of steel plates.