The Department of Energy's Office of Environmental Management is continuing efforts to clean up nuclear waste left over from Cold War-era weapons production. It recently released a "roadmap" that seeks to outline strategies for a safer and more efficient cleanup process at the nation's 16 remaining waste sites, to be implemented over the next ten years.

The roadmap aims specifically to examine technologies applied in the storage and transportation of waste consisting mainly of plutonium, uranium and spent nuclear fuel. The document also focuses on remediation of contaminated soil and groundwater, strategies to safely deactivate and decommission aging waste storage facilities, and methods for reducing health hazards for the office's 34,000-member workforce.

During the Cold War, safety procedures and waste storage methods at the nation's multiple nuclear weapons facilities were largely inadequate and deficient. Waste was often stored in underground carbon steel containers whose integrity over many decades has been compromised due to corrosion, allowing toxic material to leak into the air and groundwater around those sites.  

The Office of Environmental Management was established in 1989 as part of an effort to centralize management of the DOE's waste sites and to deal with enhancing the safety and effectiveness of remediation. According to Mark Gilbertson, EM's Deputy Assistant Secretary for Engineering and Technology, the program originally managed 105 sites, of which 89 have been cleaned thus far.

"Originally the cleanup program was in the area of 2 million acres overall-the area [in terms of size not location] of Rhode Island and Delaware combined," says Gilbertson. "We have about two hundred storage tanks...about 88 million gallons of liquid radioactive waste. We deal with enough nuclear waste that would fill a superdome."

The new roadmap acts as a guide for how to best deal with the remainder of the waste as safely and efficiently as possible.  

"We highlight [in the roadmap] what the nature of our technical risks and uncertainties are with the program and then lay out strategies that we would like to implement as we move into the future. We have things in there like how do you better remove waste from the tanks...how do we determine how waste would perform over long periods of time."

Methods for waste removal

One novel method is slated to be used at the 586-square-mile Hanford Nuclear Reservation, situated along the Columbia River in the southeastern part of Washington State. The site currently houses 53 million gallons of liquid waste in massive underground tanks, and the Department of Energy is shelling out $690 million a year there for the construction of a vitrification plant that will be used to solidify the highly toxic contents of those tanks.

As Gilbertson explains, the tanks' most potent contents consist of a peanut butter-like mixture of sludge and salt cake-sodium nitrite and nitrate crystals formed as a result of evaporation over several decades' time. The sludge and salt cake are separated from the more "inert materials" by adding water and agitating. After the sludge is separated from the less potent matter, it is blended with liquid glass-a process that allows it to solidify and "become very stable over long periods of time."

Once the glass hardens it is placed inside stainless steel containers, most of which will be placed inside tunnels dug into stone foundations at Nevada's Yucca Mountain. Another waste isolation pilot plant exists in New Mexico, where the tanks are placed inside salt foundations. "When they close up the tunnel," says Gilbertson," the salt creeps around and entombs it." The idea is for the material to eventually decay, although he readily admits it is a process that can take "years and years and years and years and years."

History of the Hanford Site

The Hanford Nuclear Reservation was originally the site of the world's first full-scale plutonium reactor, built in 1943 as part of the Manhattan Project. It produced plutonium used in the atomic bomb dropped on Nagasaki, Japan in 1945 and later housed nine reactors that supplied weapons-grade material for three-quarters of the U.S. nuclear arsenal during the Cold War. It was officially decommissioned in 1990, and the waste tanks have remained at the site since.

The Environmental Protection Agency considers Hanford to be the most contaminated place in the Western Hemisphere and cleanup efforts there have been expensive and problematic, according to Pamela Brown Larsen, executive director for Hanford Communities, an independent organization that acts as liaison between local communities and the regional DOE office.

"There were five different chemical separation processes used during the plutonium production years," she says. "And so the waste that was generated is more complicated, more complex than what was generated, for example, at the Savannah River Site (South Carolina)...or by nuclear weapons production in France or England. It's taken longer for them to figure out how to deal with these 53 million gallons."

Another problematic aspect of cleanup at Hanford revolves around extensive soil contamination, which Larsen explains occurred when close to 500 billion gallons of liquid "that wasn't as contaminated" were poured into massive ditches near the processing facilities. For years, workers at the site went under the assumption the liquid would simply evaporate-since Hanford is located in an arid desert climate-and that "rain and surface water would not move those contaminants through the soil into the groundwater."

However, the liquid has not evaporated and the fear now exists that groundwater could be contaminated and seep into the Columbia River, which supplies drinking water to nearly one million people in surrounding communities and may well threaten sensitive fish habitats.

"It's the life-blood of the Northwest," Larsen states. Though she points out that currently Columbia is considered a "Class A" river and the water has been deemed safe for consumption.

DOE Cleanup Program Status

To date, the Department of Energy has spent a total of $75 billion on nuclear waste remediation. Environmental Management's budget for 2008 is $5.7 billion and the DOE is asking for $5.5 billion in 2009, according to the department's current Congressional Budget Request. Yet, according to Larsen, the budget appropriation for Hanford falls far too short.

"The challenge at Hanford is that there is so much money required to just keep the lights on and keep everything safe and assure that there's no further harm to the people and the environment," she says.

Larsen says the total budget slated for Hanford in 2008 is close to $1.9 billion, of which roughly half is dedicated to soil remediation and the other half to the waste tank program and construction of the glass facility. However, the 2009 budget cuts the amount slated for soil cleanup by about $35 million, and Larsen stresses the overall Hanford budget needs an additional $200 million in 2009 to remain effective.

"At this point in time, we're very concerned that the budget cuts are going to result in the cleanup being delayed or taking significantly longer," she says.

Yet, Larsen is quick to point out the new roadmap will have a significantly positive impact on the Hanford project, citing the necessity to examine new technologies to deal with the cleanup effort.

"Given the complexity of the contaminants that need to be cleaned up," she says, "there has been a need to develop new technology to address those contaminants. There's been such good progress at Hanford, we're very hopeful that progress will continue."

Asked about concerns the project may be indefinitely delayed due to budget problems, Larsen replied: "We're not willing to accept that."