AIKEN, S.C. – EM workers at the Savannah River Site recently cleared a path to move bundled spent nuclear fuel assemblies vertically instead of horizontally, a change to increase the efficiency of this process by 25 percent.
Employees from Savannah River Nuclear Solutions (SRNS), the site’s management and operations contractor, relocated storage racks no longer in use to create the path. That allowed them to move an interim bucket storage closer to the location where spent nuclear fuel casks are unloaded at the site’s L Area Basin Disassembly Basin. Bucket storage is used to unload fuel from the casks and store it for eventual processing. This storage method allows casks to be removed from the basin quickly, saving time and money.
“The basin travel path modifications will allow our operators to be dressed out in their personal protection equipment for shorter durations, reducing the potential for heat stress. It also saves half a shift worth of work for each cask processed, leading to a 25-percent efficiency gain,” DOE-Savannah River Nuclear Materials Manager Maxcine Maxted said. “This will ultimately save DOE money from more efficient operations and ensure our ability to meet our commitments.”
The casks arrive at the basin from off-site foreign and domestic research reactors via truck and are unloaded within an underwater pit in the transfer bay. Crews bundle the fuel assemblies and move them through the basin to storage locations. The fuel returns to the transfer bay before it is shipped by rail to the site’s H Canyon to be processed into a low enriched uranium solution, which can be used to create fuel for commercial nuclear reactors.
“All fuel loading and unloading happens in the transfer bay, so it really becomes a choke point for our work,” SRNS L Area Facility Manager Lakela Lofton said. “We have to carefully plan when we receive incoming shipments around shipments to H Canyon for processing. To address this issue, L Area management organized a continuous improvement event involving some of the best minds in our organization to come up with a way to accelerate and increase availability of our transfer bay.”
Workers turn the fuel bundles horizontally to move them to the transfer bay for loading into a 70-ton cask for shipment to H Canyon.
“Turning the fuel bundle horizontally while keeping it under water is time consuming and precarious work,” Lofton said. “Specialized tools are used to slowly lift the bottom end of the fuel bundle by operators standing on platforms above.”
The SRNS team recognized that keeping the 11.5-foot-tall fuel bundles vertical in transit would save time and effort. However, the team needed to ensure appropriate space between the bundles and adequate water depth for radiation shielding to protect workers.
“The primary concern was that if the vertical fuel bundle inadvertently fell while transferring, it would have the potential of interacting with other fuel,” Lofton said.
The team moved the unused storage racks to ensure that if a fuel bundle fell, it would only interact with empty racks.
“We expect to be able to start moving fuel vertically early in 2020, which will allow us to process fuel more efficiently,” Lofton said.