AIKEN, S.C. – Employees at the Savannah River Site (SRS) recently began underwater vacuuming to remove resin from a reactor’s spent nuclear fuel cores.
“In the early ‘90s, resin was deposited on a number of High Flux Isotope Reactor (HFIR) cores during L Area Basin operations,” said Neil McIntosh, L Area facility manager at Savannah River Nuclear Solutions (SRNS), the site’s management and operations contractor. “The resin deposits rendered the cores unsuitable for dissolution and processing in H Canyon, which is the disposition path for this type of fuel.”
As a result, the site’s spent nuclear program created an innovative method for resin deposit removal while the cores remained underwater to maintain adequate shielding from radiation, McIntosh said.
The HFIR is the highest flux reactor-based source of neutrons for research in the U.S. using highly enriched uranium. The fuel elements, an inner and an outer element, together form a reactor “core.” The reactor is located at Oak Ridge National Laboratory in Tennessee.
Before beginning vacuuming, personnel went through extensive training involving mock fuel and used virtual reality to practice the operation.
“Installation of the vacuum station and the start of vacuuming were completed ahead of schedule, even with the delays associated with the COVID-19 pandemic,” said McIntosh. “Once the cores are vacuumed clean of resin, they can be sent for further processing in H Canyon.”
At H Canyon, the cores are dissolved in nitric acid and the resulting materials are dispositioned as authorized by DOE.
“Thanks to the innovation of the L Basin team, we are able to clean and process the affected HFIR cores,” DOE Nuclear Materials Senior Technical Advisor Maxcine Maxted said. “Accelerating the de-inventory of L Basin moves us closer to our long-term goals of environmental cleanup.”
All vacuuming of HFIR spent nuclear fuel cores is scheduled for completion by fiscal year 2023.
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.