The Search for Element 61

Abstract

The Oak Ridge National Laboratory was established during the Second World War. Its primary objective, as a part of the Manhattan Project in 1943, was the development, as rapidly as possible, of a feasible process for the production of the fissionable nuclides, Pu²⁴⁰ and U²³⁵ at a purity level and rate sufficient for the assembly of the nuclear bomb which was under development concurrently at the laboratory complex established in the University of California Project at Los Alamos, New Mexico (1,2) as another part of the Manhattan Project. In the Oak Ridge, Tennessee complex the Clinton Laboratories, identified as X-10 at the time (1943), were operated by the University of Chicago. It was involved with the development of a chemical process for the separation of slow-neutron fissionable Pu²⁴⁰, produced in the graphite-moderated nuclear reactor built for this purpose, from the components of the fuel elements and the radioactive products formed simultaneously. Research programs to develop a technique for the separation of the slow-neutron fissionable U²³⁵ isotope from its much more abundant naturally occurring isotope, U²³⁸, were carried out in two other installations in Oak Ridge. The first of these, known as Y-12, was operated by Tennessee Eastman and examined electromagnetic techniques for their separation. Union Carbide was in charge of operations at K-25, the second installation used to examine the feasibility of uranium isotope separation by a gaseous diffusion process. In this process advantage was taken of mass-based differences in the diffusion of U²³⁵F₆ and U²³⁸F₆ through porous barriers.