Method for Cleaning Spent Nuclear Fuel Created

 Method for Cleaning Spent Nuclear Fuel Created

A collaboration of investigators at the Sandia National Laboratories (SNL) announces the development of a method for removing dangerous gases from spent nuclear fuels. This could finally enable the production of cleaner, safer nuclear energy around the world.

At the same time, the innovation would also contribute to reducing the amount of radioactive waste currently being produced by power plants and medical isotope production facilities. Together, these sources produce large volumes of wastes that are extremely difficult to manage.

In the United States, the Yucca Mountain project has been on hold for years. This was to be a facility designed specifically for handling such dangerous chemicals, by storing them underground. By using the new approach, such expensive and potentially-dangerous endeavors may no longer be needed.

In order to capture and remove volatile radioactive gas, SNL investigators decided to use something called metal-organic frameworks (MOF). These crystalline compounds can be used to construct 1- through 3-D structures that can be designed to exhibit extreme porosity. 

SNL Surface and Interface Sciences Department chemist Tina Nenoff explains that the MOF could be used both for nuclear fuel reprocessing, and for nuclear reactor accident cleanup efforts. “This is one of the first attempts to use a MOF for iodine capture,” she explains. 

“The goal is to find a methodology for highly selective separations that result in less waste being interred,” Nenoff goes on to say. The reason why iodine is the primary target of such studies is that it has a half-life of about 16 million years.

What this means is that it can act on the environment for prolonged periods of time, and also that it has the potential to contaminate everything it comes in contact with in the meantime. Researchers took inspiration from a material called silver-loaded zeolite.

“Silver attracts iodine to form silver iodide. The zeolite holds the silver in its pores and then reacts with iodine to trap silver iodide,” the expert says. However, silver is too expensive for wide-scale use, so the SNL group developed an MOF that featured the zeolite Mordenite.

The material displays numerous pores, a high surface area, as well as extreme stability and chemical absorption rates. Furthermore, the MOF that results from this compound can be fashioned into pallets, and then be stored in glass residues after it captures radioactive iodine isotopes. 

The SNL is operated by Lockheed Martin's Sandia Corporation, under a contract with the US Department of Energy’s (DOE) National Nuclear Security Administration (NNSA).