New Nuclear Reactors and Waste Management: What’s Changing?
Nuclear power plants produce 10% of the world’s electricity, but the way we deal with nuclear waste is as varied as it is creative. New nuclear reactor designs could introduce new wrinkles for nuclear waste management.
The Current State of Nuclear Waste Management
Nuclear waste can be roughly split into two categories: low-level waste and high-level waste. Low-level waste, like contaminated protection equipment from hospitals and research centers, can be stored onsite and often handled like regular trash once its radioactivity has decayed enough. High-level waste, on the other hand, is much more radioactive and often quite hot.
Many experts agree that the best long-term solution for spent fuel and other high-level nuclear waste is a geologic repository—a very deep, very carefully managed hole in the ground. Finland is the furthest along with plans to build one, and its site on the southwest coast of the country should be operational this year.
New Reactor Designs and Waste Management
New nuclear reactor designs could require tweaks to ensure that existing systems can handle their waste. Some new reactors will look quite similar to operating models, so their spent fuel will be managed in much the same way that it is today. But others use novel materials as coolants and fuels.
“Unusual materials will create unusual waste,” says Syed Bahauddin Alam, an assistant professor of nuclear, plasma, and radiological engineering at the University of Illinois Urbana-Champaign.
TRISO Fuel and High-Level Waste
Some advanced designs could increase the volume of material that needs to be handled as high-level waste. Take reactors that use TRISO (tri-structural isotropic) fuel, for example. TRISO contains a uranium kernel surrounded by several layers of protective material and then embedded in graphite shells.
The graphite that encases TRISO will likely be lumped together with the rest of the spent fuel, making the waste much bulkier than current fuel. Today, separating those layers would be difficult and expensive, according to a 2024 report from the Nuclear Innovation Alliance.
Liquid-Fueled Molten-Salt Reactors and Waste Volume
Liquid-fueled molten-salt reactors, another new type, could increase waste volume too. In these designs, fuel and coolant are not kept separate as in most reactors; instead, the fuel is dissolved directly into a molten salt that’s used as the coolant.
That means the entire vat of molten salt would need to be handled as high-level waste. On the other hand, some other reactor designs could produce a smaller volume of spent fuel, but that isn’t necessarily a smaller problem.
Fast Reactors and Heat Generation
Fast reactors, for example, achieve a higher burn-up, consuming more of the fissile material and extracting more energy from their fuel. That means spent fuel from these reactors typically has a higher concentration of fission products and emits more heat.
And that heat could be the killer factor for designing waste solutions. Spent fuel needs to be kept relatively cool, so it doesn’t melt and release hazardous by-products. Too much heat in a repository could also damage the surrounding rock.
Location, Location, Location
Regardless of what materials are used, even just changing the size of reactors and where they’re sited could introduce complications for waste management.
Some new reactors are essentially smaller versions of existing reactors, but they could be sited in different locations, which could affect waste management. For example, a smaller reactor might be sited in a more urban area, which could make waste management more complicated.
Conclusion
New nuclear reactor designs could introduce new wrinkles for nuclear waste management. While some new reactors will look quite similar to operating models, others use novel materials as coolants and fuels, which could create unusual waste.
The best long-term solution for spent fuel and other high-level nuclear waste is a geologic repository—a very deep, very carefully managed hole in the ground. Finland is the furthest along with plans to build one, and its site on the southwest coast of the country should be operational this year.
As new nuclear reactor designs emerge, it’s essential to consider how they will affect waste management. By understanding the challenges and opportunities presented by new reactor designs, we can work towards a more sustainable and responsible nuclear energy future.
