Innovator | Chien Wai

Few people would see a connection between decaffeinating coffee beans and recycling nuclear waste, but Chien Wai, professor of chemistry, certainly did.
The same basic principles used in the decaffeination of coffee beans can be modified to extract usable enriched uranium from the ashes of low-level radioactive waste.

After years of trial and error, Wai came up with a system that worked and licensed the technology to international nuclear giant AREVA. The technology will be used in a recycling plant near Richland, Washington that will immediately start working on 32 tons of incinerator ash currently piled at the nearby enrichment plant.

Low-level nuclear waste includes common, everyday objects like air filters, gloves and lab coats that slowly become contaminated anywhere that uses radioactive materials. The most common producers of this type of waste are nuclear energy plants, uranium enrichment plants and hospitals, among others. The sheer volume of this waste is difficult to deal with; so many institutions are allowed to burn it, reducing its volume by 90 percent.

But it turns out that nearly 10 percent of that waste is usable enriched uranium meaning that there is currently about $5 million worth of nuclear fuel just sitting around in the Washington desert.

And nearly 40 years ago, Wai decided to go get it.

The process of decaffeinating coffee beans involves supercritical carbon dioxide. Most people know carbon dioxide as a gas or bubbles in our soda. But raise the temperature and pressure just a little bit, and the gas takes on the properties of both a liquid and a gas. It can move directly into a solid object like a gas and dissolve chemicals and compounds like a liquid.

But because CO2 cannot directly dissolve metals, a binding agent called a ligand must be introduced. Once the ligand is applied, the supercritical CO2 flows through the waste, dissolving both the ligand and the metals bounded to it. Then, when the CO2 is returned to normal pressure, it becomes a gas and evaporates, leaving behind only the extracted metal; enriched uranium in this case.

So in the end, tons of enriched uranium that was previously harmful to the environment will be extracted and reused for energy. The formerly radioactive ash pile will be easier to manage and the whole process is environmentally friendly. No solvents are used, no acids applied and no organic waste is left behind.

If all goes according to plan, the recycling plant will get through the waste in Richland and begin taking in similar waste from other sites around the country. Tons of formerly dangerous waste will no longer be harmful, tons of usable nuclear fuel worth millions of dollars will be recovered, the plant will provide jobs for the community, money will be made for the state of Washington and the University of Idaho, and similar plants will be built around the world.