Nuclear powerNew fuel materials to make nuclear reactors safer
Nuclear power is an important energy source in the United States and around the world and is essential as a clean energy to reduce current carbon emissions from fossil fuels. However, many people feel the risk of nuclear accidents does not outweigh the benefits associated with nuclear energy. Scientists are exploring new materials for nuclear fuel, which could make current light water reactors (LWRs) safer.
Nuclear power is an important energy source in the United States and around the world and is essential as a clean energy to reduce current carbon emissions from fossil fuels. However, many people feel the risk of nuclear accidents does not outweigh the benefits associated with nuclear energy.
Michael Tonks, assistant professor of mechanical and nuclear engineering at Penn State and director of the Microstructure Science and Engineering Laboratory at Penn State, is involved with three projects through the Department of Energy’s Nuclear Energy University Program (NEUP). These projects are exploring new materials for nuclear fuel, which could make current light water reactors (LWRs) safer.
Penn State notes that these projects all fall under the broad topic of accident tolerant fuels, or fuels with enhanced tolerance to withstand loss of coolant during a nuclear accident for considerably longer than traditional fuels. The extra time gives reactor operators more time to resolve problems before there are large consequences. Accident tolerant fuels also need to have similar or improved performance compared to current fuels and be cost effective.
“The issues with the Fukushima Daiichi nuclear reactor accident were actually direct issues with the choice of material for the fuel and cladding,” Tonks said. “And so the idea is that maybe we can change the fuel material or the cladding material, but keep everything else in the reactor the same.”
Cladding is the metal that surrounds a stack of fuel pellets and separates the fuel from the coolant inside the reactor.
Altering the fuel and cladding is a more cost-effective and near-term solution than replacing existing nuclear reactors with newly designed reactors, and it could drastically change the future and safety of nuclear energy.
The nuclear fuel used in all LWRs in this country is uranium dioxide and the cladding material used in these LWRs is a zirconium alloy. These materials have properties that make them very good choices for use in nuclear reactors and they continue to perform well. However, they also have issues that keep them from holding up well in accident conditions.
Uranium dioxide has very low thermal conductivity, which means it traps heat inside the fuel pellet. Not only is the low thermal conductivity counterproductive to a nuclear reactor’s goal to generate heat, but it can also cause the fuel pellets to overheat and even melt when a reactor loses coolant.
