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Published: 1976

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Volatilities of a zinc borosilicate glass containing 25 wt. percent simulated high-level radioactive waste calcine and of the calcine itself were determined in the range 800 to 1200°C. The fission products Rb, Mo, Ru, Te, and Cs were detected in the vapor from both the glass and the calcine. In general, the vaporization rates were lower from the glass with the exception of Rb and Cs at 1200°C, where the rates were about the same from the glass as from the calcine. Furthermore, slopes of Arrhenius plots for Rb and Cs were higher for the glass indicating that more of these elements would be lost from the glass above 1200°C than from the calcine. Vaporization of all volatile elements from the glass seems to be dominated by a single mechanism; thus, vapor composition over the glass is essentially temperature independent. Several mechanisms apply to vaporization of the various elements from the calcine. Gross weight-loss from the glass and calcine appears to be surface and diffusion controlled, respectively.