The results of a series of neutron diffusion calculations relating to an untamped Orally sphere are presented in detail in this report. The three-velocity neutron transport theory was taken as the basis for the analytical work preceding the computations. This particular theory, also known as the transport approximation, is defined in LA-1271 and known to be quite accurate for assemblies primarily involving materials of large atomic weight. For a sphere of uniform density and atomic composition the transport theory has another advantage. It can readily be formulated in terms of simultaneous integral equations (in our case three), relatively simple in form, involving the collision densities [formula] and a set of parameter values describing the materials. Nb(r) is , as indicated, a function of the radial distance [formula] and the velocity index g, g - 1, 2, 3. The parameters, fifteen in number for the three-velocity theory, are comprised of the velocities, the inverse mean free paths, and the transfer coefficients.

Critical mass of an Oy (93.9%) sphere in graphite is given as a function of graphite tamper thickness. It was shown that approximately 20(in) of graphite is effectively infinite and that the approximately 17(in) used herein is approximately 98% infinite. Critical mass measurements of Oy (93.9%) spheres and cylinders of different diameters are given for approximately 17(in) graphite tamper, for effectively infinite paraffin tamper, and for effectively infinite water tamper. From these measurements cylindrical shape factors were computed. Both shape factors and critical masses are shown in Figs. 22 and 23 as function of the critical height to diameter rate of the cylinders.

Design and construction of remote control equipment for plutonium metal production are described. Criteria for the design of the equipment included the following: rubber gloves were to be completely eliminated; all mechanisms were to be built as integral units to facilitate replacement through use of the plastic- bag technique; no accessory equipment such as switches, valves, piping, or cylinders were to be inside the contaminated enclosure unless required to handle the plutonium; and all units were to be tested in mockups before final design. The chemical process, general layout, and operating function are outlined. Descriptions are given of all mechanical units, electrical systems, hydroxide slurry systems, ventilation systems, and chemical tanks and manifolds. (W.L.H.)