SRS crews could double-stack 300 waste canisters in fiscal 2025

Crews at the Department of Energy’s Savannah River Site (SRS) are expected to double-stack 300 canisters of vitrified high level waste this fiscal year ending Sept. 30. 

That figure would continue a decade-long mission that is conserving space at the South Carolina complex, according to the DOE.  

 To date, liquid waste contractor BWX Technologies-led Savannah River Mission Completion (SRMC) has double-stacked 182 canisters in fiscal 2025, according to an SRS spokesperson. The 300-canister mark will continue a downward trend in recent years, which has included: 368 canisters in fiscal 2022; 349 canisters in 2023; and 333 canisters in fiscal 2024..

 The double-stacking method includes using a cutting tool to remove an existing steel crossbar from each canister support in the below-grade vaults. From there, the removed crossbar is replaced with a plate that rests on the vault floor, increasing the available height so canisters can be stacked on top of each other.

 The method was deemed necessary in 2015 after it was determined that the total canister space in Glass Waste Storage Buildings (GWSB) 1 and 2 was less than the total number of canisters expected to be produced from liquid waste processing. A year later, double-stacking in GWSB 1 began at the 310-square-mile Savannah River Site.

 “Double-stacking saves the federal government an estimated $100 million or more by avoiding construction of a third canister storage building,” the SRS spokesperson said.” The spokesperson did not immediately have exact figures. 

To date, 2,596 canisters have been placed in double-stack positions in GWSB 1, according to the spokesperson. A total of 4,524 canisters in GWSB 1 will be double-stacked. Work began earlier this year to expand storage space in GWSB 2, which will eventually house 3,510 double-stacked canisters, and 585 singular canisters. Modifications in the second storage building are expected to be completed by September 2030 and will save another $100 million.

 “Once completed, this strategy will increase the total storage capacity (in both GWSBs) to a planned 8,619 canisters,” the spokesperson added.

The SRS liquid waste mission includes the removal of more than 30 million gallons of Cold War-era liquid waste, stored in 51 underground waste tanks. To date, eight of those 51 tanks have been operationally closed.

 About 90 percent of the waste in those tanks is salt waste and is treated through the Salt Waste Processing Facility before being permanently stored in Saltstone Disposal Units on site. The rest is sludge waste and is treated at the Defense Waste Processing Facility before it is placed in canisters and temporarily stored in the GSWBs until a federal repository for high-level waste is established.

 Overall, the mission is expected to last until 2037.