[en] This Notice of Construction (NOC) presents the required information regarding Phase 1 and 2 of the decommissioning of the 233-S Plutonium Concentration Facility Complex (233-S Complex). Phase 1 includes preparing the site, setting up temporary containments where required, removing inventory and equipment, and final decontamination of the structure. Phase 2 includes dismantling and removing the structure and final site stabilization. The project will include techniques that minimize the volume of the waste. Radioisotopes found include neptunium 237, plutonium 237, 238, 239, 240, 241, and 242, and americium 241. The 233-S building was designed and operated to concentrate the plutonium solutions generated by the REDOX Plant using an ion-exchange process. The process was expanded in 1962 to include neptunium received from the REDOX Plant