US tech could boost energy extraction from nuclear fuel, reduce radioactive waste

Researchers at the University of Mississippi have found that embedding metallic fission fuel with uranium nitride nanoparticles can help improve the lifetime and safety of fission reactors. Additionally, the approach also helps reduce radioactive waste generated by fission plants, thereby improving the adoption of this source of energy.

Nuclear fission technology is well known for its ability to produce large amounts of energy without generating any carbon emissions. Compared with renewable sources of energy like solar and wind, nuclear fission reactors require a fraction of the land. Yet, they are not the top choice for countries looking to improve energy production capacities. Even in the US, nuclear fission reactors only supply 20 percent of the electricity generated.

Much of the resistance to the adoption of fission energy is due to the generation of radioactive waste. A research team led by Samrat Choudhury, an associate professor of mechanical engineering at the University of Mississippi, explored ways to reduce waste and found an innovative approach.

Challenges with nuclear fuel When a nuclear reactor is operational, the metallic fuel inside it swells and contacts the reactor s cladding. The cladding is designed to be the protective shell that prevents the radioactive fuel and its byproducts from reaching the reactor wall. However, over time, when the swollen metallic fuel repeatedly comes into contact with the cladding, the latter degrades and becomes brittle, thereby shortening the reactor s lifetime.

Choudhury and his team were looking for ways to trap the fission materials within the metallic matrix and prevent them from reaching the cladding. Previous research by the team showed that forming tiny uranium nitride particles in the fuel could help capture fission gases and other byproducts. Increasing the life of the fuel and the reactor In their recent work, the researchers tested the nanoparticles and found that the interface between uranium-nitride nanoparticles and metallic fuel could be used to capture the fission products.

If you can leave the fuel longer in the reactor and get all the energy that can be extracted from it, then the rate at which you are accumulating spent fuel will slow down, explained Indrajit Charit, chair of the Department of Nuclear Engineering and Industrial Management at the University of Idaho. “Fuel burnup is also dependent on the cladding performance. If the cladding is breaking, you cannot just leave the fuel inside. So, this research also helps us improve both fuel burnup and efficiency.

“If we can use the fuel for a longer period of time, there is a potential to decrease the amount of waste we generate, added Choudhury. “If we can reduce the waste substantially, adopting nuclear energy is going to get a lot easier.” However, before this becomes a reality, the researchers need to demonstrate their technology under real-world conditions.

The team will now focus on perfecting their nanoparticle-laced fuel recipe and then find an industry partner to test it. “It takes a long time to mature these technologies and get to a level where companies would adopt them, but this is the first step,” concluded Charit. The research findings were published in the journal Advanced Materials Interfaces.