AIKEN, S.C. – EM and the management and operations contractor at the Savannah River Site (SRS) recently used underwater cameras for the first time to complete examinations of non-aluminum-clad spent nuclear fuel bundles stored in a basin, helping ensure the integrity of the storage systems.
Most spent nuclear fuel stored in the site’s L Basin is covered, or clad, in aluminum and then placed in aluminum bundles. However, a small portion of the fuel in L Basin is housed in aluminum bundles but clad in stainless steel or zirconium alloy, a type of metal know for its hardness and corrosion resistance.
“We needed a way to inspect the aluminum bundles that house non-aluminum-clad spent nuclear fuel to make sure galvanic corrosion wasn’t occurring,” Savannah River Nuclear Solutions (SRNS) Augmented Monitoring and Condition Assessment Program (AMCAP) Manager Michelle Hromyak said. “Galvanic corrosion happens when two metals that are dissimilar in nature — in this case the aluminum bundles and the zircalloy or stainless steel-clad spent nuclear fuel — are closely coupled underwater and one metal corrodes the other.”
AMCAP provides examination capabilities of the spent nuclear fuel to help extend the safe storage of the material until its final disposition.
After specifically selecting the cameras to withstand the radiochemistry of the water while being submerged approximately 30 feet into the basin, SRNS worked with Savannah River National Laboratory (SRNL) to design the long-handed tools to hold the cameras during the inspections.
In advance of the examinations, SRNL and SRNS developed a mock-up to test the cameras and the accompanying long-handled tools.
“Over the next few years, we plan to continue visual examinations to ensure fuel integrity,” Hromyak said. “With SRNL’s help, we are also developing ultrasonic testing capability to validate the integrity of the fuel inside the bundles and determine if any worsening storage conditions are occurring that we cannot see with just visual examinations.”
Spent nuclear fuel is nuclear fuel that has been irradiated in a nuclear reactor. The spent nuclear fuel from the site’s former production reactors, and from foreign and domestic research reactor programs, is safely stored in an underwater storage facility in L Area, called a disassembly basin.
L Basin has concrete walls up to 7 feet thick and holds approximately 3.4 million gallons of water, with pool depths up to 50 feet. The basin water provides shielding to protect workers from radiation. Since 1964, SRS has received more than 2,400 casks containing over 47,500 spent nuclear fuel assemblies.
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