COLLEGE STATION --
The federal government has a problem -- what to do with 65 million gallons of nuclear waste, enough to fill 2,000 swimming pools.
Texas A&M University chemists may have a solution. They have developed a way to remove the most potent radioactive elements from the waste, making disposal easier and cheaper. The waste sits at the Hanford Processing Site in Washington state, and it has started to cause problems.
"A lot of the tanks are starting to leak into the environment," said Elizabeth Behrens, a Texas A&M doctoral student. "The government is looking for ways of economically reducing the volume of waste and disposing of it in a safe manner, so it won't create any more environmental damage or harm to the public."
The production of nuclear weapons at Hanford left behind highly radioactive forms of the elements strontium and cesium. This waste was dumped into steel tanks and half-buried on the processing site. The tanks have started leaking. Strontium is slowly contaminating groundwater, Behrens said, posing a threat to humans and wildlife.
"Strontium is like calcium," she said. "If you ingest it, it goes directly to your bones, where it sits and starts to decay and possibly causes cancer."
Normally such high-level radioactive waste must be turned into glass logs, which are wrapped in steel and buried deeply. The government is looking for ways to convert this high-level waste into less harmful forms, which are cheaper to dispose of.
Behrens has developed a way to remove strontium and cesium from the waste by exchanging them with the less harmful sodium. The process uses an ion exchanger, a device that can selectively remove elements from a solution and replace them with other elements.
By removing the most radioactive ingredients, this exchange renders the toxic witch's brew less radioactive, so it can be mixed with cement and safely buried.
"Since each glass log costs about $1 million, they want to minimize the number of glass logs they make and maximize the low-level waste, which can be disposed of inexpensively," she said.
The trick is in removing the strontium and cesium, which are surrounded by huge amounts of sludge. It's like looking for a needle in a haystack, she said.
Chemistry professor Abraham Clearfield, who supervises Behrens and other graduate students working on similar projects, said their research has produced compounds that are inexpensive yet effective.
Still, the researchers must sell their ideas to the big research corporations that Congress has asked to study cleaning up the Hanford site.
"Once they get going on the remediation, they're going to have some surprises because in many cases they don't know what's in the tanks," he said. "We feel they need not one or two but at least a dozen materials to use in the cleanup. That way they can decide which material is best suited for a particular pollutant."
Behrens hopes they choose hers.
"Your job is to find something that does just as well or better than their favorite material," she said. "Mine competes with theirs. In some areas, it competes with the leading materials favored by the national laboratories."
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