In a follow-up to prior reports, the Government Accountability Office said again Friday that using concrete-like grout would be a cheaper way to solidify the less-radioactive tank waste at the Department of Energy’s Hanford Site in Washington state.
The Savannah River Site in South Carolina has treated 4 million gallons of its radioactive salt waste using grout and the Government Accountability Office (GAO) calculates that given price escalation, DOE could save $95 billion over the next 60 years by grouting some of the low-level liquid waste at Hanford.
The best available data indicates the cost per curie of DOE vitrifying 50 million gallons of liquid low-level waste into glass at Hanford would be $17,500 with a cost-per-gallon of $1,400, GAO said. By contrast, the Savannah River Site’s cost per-curie cost for treating 36 million gallons of salt waste is $2,300 with a cost per gallon of $200.
Low-activity waste, as DOE calls it, accounts for 95% of the volume but only 3% of the radioactivity, of an estimated 54 million gallons of liquid waste at Hanford, GAO said. But the Bechtel-built Waste Treatment and Immobilization Plant can only process about 60% of this low-activity waste, GAO said.
DOE has yet to decide what to do with the remainder, GAO said in its Sept. 29 snapshot report. Research over the past couple of years by a Savannah River National Laboratory team and the National Academies of Science suggested grout could be a viable future alternative at Hanford. DOE and Washington state are already moving toward a 2,000-gallon demonstration grout test for Hanford liquid tank waste.
As a matter of policy, DOE currently treats all Hanford tank waste as if it is legally “high-level radioactive waste,” GAO said. High-level waste must end up buried in a deep underground repository, which does not currently exist. The grouted material from the demonstration project would be disposed of at either EnergySolutions in Utah or Waste Control Specialists in Texas, GAO noted.
The GAO has called upon Congress to clarify DOE authority to classify low-activity waste as something other than high-level waste.
