No abstract

A two-site model has been derived and tested against experimental data for monovalent species ion exchange in molten chloride salt/zeolite A. This system is of interest for the application of spent nuclear fuel treatment. Fission products and transuranics that accumulate in a molten salt electrorefining process can be preferentially removed and eventually stabilized in a waste form, using zeolite A. An excellent fit of Cs-Rb-Na-Li-K data to the model was found with different selectivity sequences for the two sites. Cesium was found to be the preferred cation in the R-cage sites, while lithium was preferred in the framework sites.

Properly formulated and properly "canned" radwaste concretes can be readily hot-isostaticallypressed (HIPed) into materials that e h b i t performance equivalent to typical radwaste-type glasses. The HIPing conditions (temperature/presswe) required to turn a concrete waste form into a "vitrified" waste form are quite mild and therefore consistent w i t h both safety and high productivity. This paper describes the process and its products with reference to its potential application to Idaho Chemical Processing Plant (ICPP) reprocessing wastes.

A cement capable of being Hot Isostatically Pressed (HIP 'ed) into a glass-ceramic has been proposed for use as the waste form for SNF reprocessing wastes at the Idaho National Engineering Laboratories. Such an “intermediate” cement, with a composition based on that of common glasses, has been designed and tested. The cement formulations included mixed I.N.E.L. wastes, blast furnace slag, reactive silica, alumina, and I.N.E.L. soil or vermiculite, which was activated with potassium or sodium hydroxide. Modified FUETAP processing was performed and the cement was subsequently characterized. Results of compressive strength testing ranged from 1452 psi to 4163 psi, exceeding the NRC-suggested standard of >500 psi. Total dissolved solids concentrations in waste form leachates were calculated from a static leach test in which leachate conductivity was measured. Effective diffusivities for radioisotopes Cs and Sr were calculated from leachate analysis data. Diffusivity values were on the order of 10-15 to 10-10 cm2/sec, which compare favorably with diffusivities in other materials.