American researchers have developed a process for removing an extremely toxic element from nuclear waste, paving the way for safer and faster disposal.
In an article published in the latest issue of the journal Science, the team from the University of North Carolina at Chapel Hill (UNC), the USA, described how they managed to remove highly radioactive americium from the nuclear waste – a problem that has puzzled researchers for decades.
"In order to solve the nuclear waste problem, you have to solve the americium problem," said Tom Meyer, Professor of Chemistry at UNC, who led the study.
The new technique breaks down americium into a more manageable material by removing three electrons. Professor Meyer used a similar technique previously to tear electrons from water molecules in a research dealing with solar energy. The only difference is that splitting americium requires twice the amount of energy as splitting water. The resulting element behaves more like plutonium and uranium, which are easy to remove from the radioactive waste with existing techniques.
According to researcher Chris Dares, nuclear fuel is initially used as small solid pellets loaded into long, thin rods. To reprocess them, the used fuel is first dissolved in acid and the plutonium and uranium separated. In the process, americium will either be separated with plutonium and uranium or removed in a second step.
The UNC researchers cooperated on the research with Idaho National Laboratory, which provided guidance on working with nuclear materials and is currently helping the team to find a way to scale up the technology.
"With a scaled-up solution, not only will we no longer have to think about the dangers of storing radioactive waste long-term, but we will have a viable solution to close the nuclear fuel cycle and contribute to solving the world's energy needs,” Dares said. “That's exciting."
Various research teams have been trying to find a way to remove americium from nuclear waste for decades. However, all previously developed techniques encountered problems rendering the solutions unfeasible. Meyer’s and Dares’s solution is thus the first that appears to be genuinely viable.
In addition to simplifying nuclear waste storage, the new technique also paves the way for closing the nuclear fuel cycle, which would enable further spread of nuclear energy generation, considered by some as a key step to reducing greenhouse gas emissions from power generation.