Abstract: A process for the recovery of chemical values, particularly uranium, nickel and/or radionuclides from process equipment theretofore employed in a uranium hexafluoride isotope enrichment cascade. Preferably, the process is carried out, in situ, at subatmospheric pressure employing the existing process equipment from which the chemical values are to be recovered. In one aspect, the process includes recovery of uranium values employing a gaseous fluorinating agent at subatmospheric pressure, followed by recovery of nickel values employing a gaseous reactant comprising a mixture of carbon monoxide and a promoter, preferably hydrogen sulfide and at subatmospheric pressure.