Material discovered to lower nuclear fuel recycling costs

A computer model has helped scientists find a new material that could help nuclear fuel recycling by capturing gases released during reprocessing.

Researchers based in Berkeley, California and Richland, Washington discovered the material, a metal-organic framework (MOF) called SBMOF-1, can remove radioactive krypton and xenon at ambient temperatures. This discovery is the result of collaboration between material scientists and computer modellers.

Praveen Thallapally, from the Department of Energy’s Pacific Northwest National Laboratory, said: “This is a great example of computer-inspired material discovery. Usually the experimental results are more realistic than computational ones. This time, the computer modelling showed us something the experiments weren't telling us.”

To capture radioactive gases given off such as krypton and xenon, entire gas streams are brought to temperatures below 0°C, which is both costly and energy intensive. This study looked at MOFs as they can trap these gases without the use of cryogenics. Containing small pores that can hold one molecule of a gas, MOFs can be used to selectively adsorb specific gases.

Maciej Haranczyk and Berend Smit from Lawrence Berkeley National Laboratory screened 125,000 possible MOFs to find one suitable for particular filtration purposes. SBMOF-1 possesses a pore size similar to xenon and was tested with a variety of gases including xenon, krypton, oxygen, helium, nitrogen and carbon dioxide. All other gases apart from xenon were able to pass through the material. It was also found in the absence of xenon, that SBMOF-1 captures krypton, so to remove both gases, researchers would run the gas streams through the material twice.

SBMOF-1 was also found to perform well in humid conditions, removing the need to dehydrate the gases, another expensive process. It also has a high degree of stability, confirmed by repeated tests in the lab.

The research was published in Nature Communications.