Behavior of helium release from simulated radioactive waste glasses.

Abstract

Rates of He release from two kinds of simulated high-level radioactive waste glasses were measured in the temperature range from 573 to 753K by a mass spectrometric method. Diffusion coefficients of He in the glasses were determined from the fractional release data. The diffusion coefficients were given as a function of temperature by the equations: D/(m2·s−1) = 2.3 × 10−6 exp (−71.1±2.1 kJ/RT) for P0798 glass =9.8 × 10−7 exp (−60.2±2.1 kJ/RT) for P0504 glass. In addition, solubilities of He in the glasses were determined from the measurement of the total amount of released He and found to be S/(atoms/m3) = 2.0 × 1022 for P0798 glass =2.2 × 1022 for P0504 glass. at 693 K and 1.7 × 105 Pa He. The diffusivities and solubilities of He in the glasses were, respectively, several and an order of magnitude lower than silica, alkali silicate and Pyrex glasses, which properties are notable for the radioactive waste glasses.