Effects of periodic manual stirring and uranium addition on surrogate plutonium glass processing

Using thorium as a plutonium surrogate, homogeneous glasses have been processed ranging from 15 to 20 elemental weight percent thorium with 0 to 5 elemental weight percent uranium. Homogeneous glasses have been processed at 1,475 C with residence times ranging from 1 to 12 hours. High ramp rates successfully inhibited thorium silicate formation. Residence times of 5 to 7 hours were required for static melts to become homogeneous for glasses containing 15 elemental weight percent thorium. Thorium dissolution rates have been determined for glasses containing 15 elemental weight percent thorium with and without the addition of uranium. When compared to identical glass compositions which were not stirred, stirred melts produced homogeneous vitreous products with an 80 percent reduction in residence time. A 20 elemental weight percent thorium glass was produced at 1,475 C by adding 2 elemental weight percent uranium. Without the addition of uranium, a melt temperature of 1,500 C was required