Radioactive waste also plays a significant role. Uranium tailings are waste by-product materials left over from the rough processing of uranium-bearing ore. They are not significantly radioactive. Mill tailings are sometimes referred to as 11(e)2 wastes, from the section of the Atomic Energy Act of 1946 that defines them. Uranium mill tailings typically also contain chemically hazardous heavy metal such as lead and arsenic. Vast mounds of uranium mill tailings are left at many old mining sites, especially in Colorado, New Mexico, and Utah. Although mill tailings are not very radioactive, they have long half-lives. Mill tailings often contain radium, thorium and
Uranium nitride and, in particular, it undergoes an (n,p) reaction which produces significant amounts of radioactive C which would need to be carefully contained and sequestered during reprocessing or permanent storage. Each uranium dinitride complex is considered to have three distinct compounds present simultaneously because of decomposing of uranium dinitride (UN) into uranium sesquinitride (UN), and the uranium mononitride (UN). Uranium dinitrides decompose to uranium mononitride by the following sequence of reactions: Decomposition of UN is the most common method for isolating uranium sesquinitride (UN). Uranium mononitride is being considered as a potential fuel for generation IV reactors such as the Hyperion