Scientists have improved their understanding of the challenging nuclear waste that could lead to better cleanup methods. Researchers at Washington State University studied the chemistry of technetium-99, a byproduct of plutonium weapons production which is considered a major challenge for environmental cleanup.
At the Hanford Site nuclear complex in Washington, there are about 2,000 pounds of the element dispersed within about 56 million gallons of nuclear waste in 177 storage tanks.
The US Department of Energy is in the process of building a waste treatment plant at Hanford to immobilise hazardous nuclear waste in glass.However, researchers have been stymied because not all the technetium-99 is incorporated into the glass and volatilised gas must be recycled back into the melter system.
The element can be very soluble in water and moves easily through the environment when in certain forms, so it is considered a significant environmental hazard.Since technetium compounds are challenging to work with, earlier research has used less volatile substitutes to try to understand the material’s behaviour.
Some of the compounds themselves have not been studied for 50 years, 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. The research was published in the journal Inorganic Chemistry.