A study was made of the effects of substituting various fractions of borate, silicate, and mixtures of them, for phosphate, with a fixed waste composition of the Purex type. The ratio of waste to additives varied from 70 to 40 reduced atom per cent;i.e., of all known atoms except oxygen, the specified per cent came from the waste and the balance was added as the phosphorous, boron or silicon of phosphate, borate or silicate. This corresponds to a range of M/P of 3.95 to 1.13. Only at the 40 atom per cent waste level was there definite indication of improve¬ment of properties of the phosphate solid by adding borates and silicates. At the other levels there was a general deterioration. This was either in the form of increased solubility or separation into two liquid phases during melting.nSeparation of a second liquid phase is deemed a major drawback of the mixed system. It is undesirable since it will lead to fission product fractionation. One phase is of increased solubility and most generally one phase was much more viscous than the other.
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