For nearly four decades, the Fuel Reprocessing Complex (Buildings CPP-601, CPP-603, CPP-627, CPP-640) at the Idaho Chemical Processing Plant (ICPP) recovered usable uranium from spent reactor fuel. The facility was constantly evolving to process new types of spent nuclear fuel and would eventually process materials from nearly 100 different reactors. Research and test reactors located at the National Reactor Testing Station supplied a large proportion of the fuel load for the facility, along with nearly all of the fuel cores that had powered the United States Navy's fleet of nuclear submarines and surface ships. Fuels clad in aluminum, zirconium, stainless steel, and graphite were routinely processed at the plant. Custom processing capabilities were also developed through the years and a variety of valuable isotopes and inert gases were isolated and shipped to research laboratories across the country. AS ICPP scientists developed the facilities and the skills necessary to reprocess highly enriched fuels from so many different sources, they also came up with many general improvements and scientific advances in fuel reprocessing techniques and waste management as a whole. In 1992, when changing political tides and lowered demand for uranium caused the Department of Energy to halt all fuel reprocessing efforts across the country, approximately 31,432 kg of uranium had been successfully recovered at the Idaho Chemical Processing Plant. The four main buildings that housed the complex fuel reprocessing operation now await decontamination and demolition.