The Zippe-type centrifuge is a gas centrifuge designed to enrich the rare fissile isotope uranium-235 (235U) from the mixture of isotopes found in naturally occurring uranium compounds. The isotopic separation is based on the slight difference in mass of the isotopes. The Zippe design was originally developed in the Soviet Union by a team led by 60 Austrian and German scientists and engineers captured after World War II, working in detention. In the West (and now generally) the type is known by the name of the man who recreated the technology after his return to the West in 1956, based on his recollection of his work in (and contributions to) the Soviet program, Gernot Zippe. To the extent that it might be referred to in Soviet/Russian usage by any one person's name, it was known (at least