The Savannah River Site in South Carolina has begun making space to temporarily store even more canisters of vitrified radioactive waste in Glass Waste Storage Building 1 (GWSB 1) by double-stacking the canisters on top of each other, according to update issued Thursday.
Double-stacking formally started on Aug. 25, the Department of Energy facility said.
Before the waste is vitrified, or converted, it poses a much bigger threat. The original waste form dates to the Cold War-era and is a product of nuclear weapons production during that time. All told, SRS is home to about 36 million gallons of waste, a large portion of which must be converted and stored in these canisters.
The canisters stacked in GWSB 1 are filled with waste that was processed through the SRS Defense Waste Processing Facility (DWPF), which takes waste and a special glass product and heats the two products to create a molten glass. The final product is suitable for long-term storage at a repository. According to a November 2015 update, DWPF has produced more than 4,000 canisters of the waste form. To make progress in the double-stacking method, workers, starting late last year, had to relocate canisters of the waste from GWSB 1 to GWSB 2.
Each canister is 10 feet tall. There are 2,254 one-canister storage positons in GWSB 1. SRS will literally double that capacity and make 4,508 spaces to store waste. To accommodate two canisters stacked vertically, the holding slots, which stand at 21 feet deep, will need to be modified, according to previous reports from Savannah River Remediation (SRR), the site’s liquid waste contractor. For example, the crossbar base support where the canisters rest will must be removed. Also, a thick, concrete shield plug that guards against radiation will be replaced by a thinner, denser cast-iron shield plug, which will provide equivalent radiation shielding and structural support.
So far, 150 of the storage positions have been modified for double-stacking. SRS says the modifications will be completed in the next seven to eight years.
Double-stacking is expected to provide adequate storage through 2026. Storage at SRS is only a temporary solution as the nation searches for a federal repository to permanently store waste from SRS and other sites across the country. That location would have been Yucca Mountain – a Nevada site about 100 miles from Las Vegas. About $13 billion was spent on Yucca Mountain after DOE began drilling at the mountain in 1994 and President George W. Bush signed off on the repository in 2002. But that all changed in 2010 when President Barack Obama ordered work on Yucca to cease. His administration subsequently established a “consent-based” plan for storage of U.S. nuclear waste.
