A radioactive actinide metal, neptunium is the first transuranic element. Plutonium and other transuranic isotopes are produced from uranium by neutron absorption during reactor operation. The amount of transuranic transmutation is limited by the production of plutonium from uranium. Curium is a transuranic radioactive chemical element with the symbol Cm and atomic number 96. Fuel rods contain fission products and transuranic elements generated in the reactor core. As a member of the actinide series, it is the seventh transuranic element. It is the third-to-last actinide and the ninth transuranic element. Mixed waste, including transuranic mixed waste, is stored. Elements that have an atomic number greater than uranium are called transuranic ("beyond uranium"). It accepts transuranic waste generated from DOE activities. Such metals include, Lead, Cadmium, Copper, Silver, Mercury and many of the transuranic metals. Mendelevium was the ninth transuranic element to be synthesized. Fermi asked her to investigate the valence shell of the undiscovered transuranic elements. Displacement chromatography found a variety of applications including isolation of transuranic elements and biochemical entities. The naming of transuranic elements may be a source of controversy.