New clues found for nuclear waste cleanup

According to a study, the research being done on the chemistry of technetium-99 has boosted the understanding of the challenging nuclear waste and can lead to better cleanup methods.

The study was published in the journal Inorganic Chemistry.

Technetium-99 is a byproduct of plutonium weapons production and is considered a major U.S. challenge for environmental cleanup.

There are about 2,000 pounds of the element dispersed within approximately 56 million gallons of nuclear waste in 177 storage tanks, at the Hanford Site nuclear complex in Washington state.

The U.S. Department of Energy is in the process of building a waste treatment plant at Hanford, to immobilize hazardous nuclear waste in glass.

But, the researchers got obstructed during the study because not all the technetium-99 is incorporated into the glass and volatilized gas must be recycled back into the melter system.

Techtonium-99 can be very soluble in water and moves easily through the environment when in certain forms, so it is considered a significant environmental hazard.

The compounds of the element are challenging to work with, earlier research has used less volatile substitutes to try to understand the material's behavior.

"The logistics are very challenging," said John McCloy, associate professor in the School of Mechanical and Materials Engineering.

The researchers conducted fundamental chemistry tests to better understand technetium-99 and its unique challenges for storage. They determined that the sodium forms of the element behave much differently than other alkalis, which possibly is related to its volatility and to why it may be so reactive with water.

"The structure and spectral signatures of these compounds will aid in refining the understanding of technetium incorporation into nuclear waste glasses," said McCloy.

The researchers also hope the work will contribute to the study of other poorly understood chemical compounds.