Complex sentence: The Federal Protective Forces are responsible for defending Department of Energy sites at which Category I special material is stored, which generally includes Uranium-235, Uranium-233, and Plutonium-239 in certain formulations.
Split into simpler sentences: The Federal Protective Forces are responsible for defending Department of Energy sites at which Category I special material is stored. This generally includes Uranium-235, Uranium-233, and Plutonium-239 in certain formulations.