SDU 6

Savannah River Remediation's 32-million gallon saltwaste disposal unit is complete and is being tied in to other procedural elements to bring the tank into operational status at the Savannah River Site.

Aiken’s Savannah River Site is now home to the world’s largest rubber-lined tank, and the company that built it plans on filling it with a kind of cement.

Savannah River Remediation, the liquid waste management contractor at SRS, announced the tank had completed leak testing in the waning days of 2016.

Known as Salt Disposal Unit 6, the 32-million-gallon structure includes a number of features to meet unique nuclear waste needs.

The 42-foot structure contains more than 12,500-cubic-yards of concrete, including more than 200 columns within that structure. All of that concrete, as well as all other material, were only used if they met Nuclear Quality Assurance 1 specifications.

NQA-1 is a quality scale developed by the American Society of Mechanical Engineers to meet the higher safety needs of nuclear facilities. A spokesperson for SRR said one of the largest challenges in building the massive structure was finding and managing commercial vendors that could meet the strict NQA-1 standards.

The concrete will come from processing waste in aging storage tanks at SRS.

Much of the high-level waste will be turned into glass form through the Defense Waste Processing facility. The remaining material, with significantly lower radioactivity, will be turned into a concrete form and poured into SDU 6 – and subsequent tanks once this one is full.

As material flows into the tank, pressure on the walls will change. To maintain structural integrity, engineers added wire strands to the outside of the tank. The wire is about three-eighths of an inch thick but would stretch nearly 290 miles if laid out straight.

The SRR representative said experts from entities like the Army Corps of Engineers, AECOM, Savannah River National Laboratory and other nuclear industry organizations collaborated to bring the project to life.

The entirety of the tank’s inside is covered with rubber. More than 7,000 individual pieces were epoxy bonded to the tank walls and floor during construction, making SDU 6 the largest rubber-lined tank anywhere on the planet.

SRR said the next steps include tying the tank into the mechanical, electrical and processing components on site.

After start-up testing and a readiness review, the tank will placed into operation. It was not immediately clear what an exact timeline for those processes looks like.

During a tour of the site, SRR representatives said more tanks of this type will be built to accommodate waste in the future, but did not give an exact number because of fluctuations in mission and changing circumstances over time.

Thomas Gardiner covers science, energy and technology topics for the Aiken Standard. Follow him on Twitter @TGardiner_AS.