What do new nuclear reactors mean for waste?

As new nuclear reactor designs emerge in the coming years, they will likely require adjustments to existing waste management systems, according to experts including Edwin Lyman of the Union of Concerned Scientists. Some advanced reactors—such as those using TRISO fuel or molten-salt cooling—could significantly increase the volume of high-level waste or produce spent fuel with higher heat output, complicating storage and disposal plans. Fast reactors, which achieve higher fuel burn-up, generate spent fuel with greater concentrations of fission products and more heat, a factor that "really drives how much you can put inside a repository," according to Paul Dickman, a former Department of Energy and NRC official. Small modular reactors could create practical problems for the U.S., where waste is currently stored onsite at individual plants, since distributing waste across numerous small sites would be impractical. Companies designing these reactors have begun submitting waste-management plans to the Nuclear Regulatory Commission, though definitive answers about actual waste profiles will only emerge once the reactors become operational.