The U.S. Energy Department has rescinded an order that would have nearly tripled the amount of plutonium in high-level waste converted to glass at Savannah River Site.
"The Office of Environmental Management has decided not to move forward at this time with its February decision to direct contractors to start planning for higher concentrations of plutonium in waste canisters at the Savannah River Site," said Jen Stutsman, a spokeswoman at the department's Washington headquarters.
The SRS-based Defense Waste Processing Facility uses a process called vitrification to convert liquid radioactive waste into a solid glass form suitable for long-term storage and permanent disposal.
Plutonium is among many materials in the 36 million gallons of waste left behind at SRS by decades of nuclear weapons production.
The department's order to increase plutonium levels in the waste canisters -- from 897 to 2,500 grams per cubic meter -- would have reduced the number of canisters needed to accommodate the waste.
The lower concentration, however, was necessary to meet the waste acceptance criteria for the Yucca Mountain waste repository project in Nevada, where much of the vitrified waste from SRS was to eventually be buried.
The Yucca Mountain project was later canceled by the Energy Department, prompting a series of lawsuits and protests that the absence of such a facility would keep radioactive waste in South Carolina much longer, if not permanently.
The decision not to implement the higher plutonium levels resulted from the need for more study and did not arise from protests or safety issues, officials said.
Tom Clements, the southeastern nuclear campaign coordinator for Friends of the Earth, said the uncertain future of waste stored at SRS and other areas might have contributed to the decision to put the changes on hold.
"Right now, where it will eventually go is uncertain," he said. "So how do they know they will meet the waste acceptance criteria for any repository, wherever it might be? The answer is, they don't."
Clements also said it is unlikely that all of the vitrified waste canisters would have made their way to Yucca Mountain.
The repository, 90 miles from Las Vegas, would have housed 70,000 tons of waste from the nation's 104 commercial reactors, with only about 10 percent of the space reserved for defense waste, such as the canisters from SRS.
The forecasted number of canisters from SRS is about 7,200, and about 2,900 have been filled.
Clements, citing DOE reports from the Hanford Site in Washington, where a new waste vitrification facility is being built, said that eventually at least 10,000 additional canisters will need a permanent home.
Yucca was being designed to accommodate just 8,315 canisters, or 4,776 metric tons, from the entire DOE complex, meaning the facility would not have been able to bury all the vitrified waste -- even if it had been constructed as planned.
The limited capacity of such repositories is among the reasons alternatives are under scrutiny by a blue ribbon commission created by Energy Secretary Steven Chu and the Obama administration.