Saltstone, a mixture of low-level radioactive waste and cementlike grout, is pumped into underground vaults at the site, where it hardens to a stable, permanent form.
In a 289-page technical evaluation released Friday, the NRC concluded that the Saltstone Disposal Facility vaults meet most performance objectives, including resistance to intrusion from groundwater, protection of workers who operate the site and stability against earthquakes.
“However, based on its evaluation of DOE’s results and independent sensitivity analyses conducted with DOE’s models, the NRC staff no longer has reasonable assurance that DOE’s disposal activities meet the performance objective for protection of the general population from releases of radioactivity,” the report said.
The saltstone is a byproduct of ongoing efforts to dispose of 36 million gallons of material left over from Cold War nuclear weapons programs. The waste, stored in 49 underground tanks – some of which are leaking – is separated into two streams, with high-level material sent to the Defense Waste Processing Facility to be encased in glass, or “vitrified.”
The remaining low-level waste is the focus of the NRC’s report, which concluded that any ill effects could occur thousands of years after the site is officially “closed,” or permanently capped with soil. For example, one DOE model forecasts excessive radiation releases after 10,000 years, while the NRC says it could be closer to 8,000 years.
Nothing in the report indicates a current threat of release of radiation, and there is no effort to halt activity at the project, which is also subject to oversight from the South Carolina Department of Health and Environmental Control.
“We stand by ready to work with the Nuclear Regulatory Commission and the U.S. Department of Energy to resolve concerns raised in the NRC’s report on SRS’ Saltstone Disposal Facility,” DHEC Director Catherine Templeton said in a statement issued Friday on the findings. “We’ve seen the report, and we’ve already begun a careful consideration of the issues. We’ll evaluate any specific recommendations that might arise from resolution of the NRC concerns.”
Jim Giusti, an Energy Department spokesman at the site, said department officials will work to resolve any differences of opinion among agencies.
“The department is committed to the safe and compliant disposal of low activity radioactive waste, such as saltstone, and to ensure that the saltstone disposal process is protective of human health and the environment,” he said.