Maximum safe cylinder diameters, slab thicknesses, and minimum critical masses in spherical geometries for fuel of < 5.0& U-235 enrichment have been evaluated. It is of interest to know the minimum critical masses as a function of cylinder diameter for vessels that are not safe by geometry. Curves will be presented of critical masses as a function of cylinder diameter and fuel rod size for 1.6%, 3.0%, and 5.0% U-235 enriched metal-water systems.

Neutron radiation can be greatly reduced by substituting plutonium trichloride for plutonium tetrafluoride in the dry chemistry step of metal preparation. Chloride processes are now common in the metal preparation industry, and the 234-5 Developmental Laboratory has shown plutonium trichloride can be satisfactorily prepared and reduced to the metal.