The corrosion behavior of DWPF glasses [report]

W.L. Ebert, J.K. Bates
1995 unpublished
We analyzed the corroded surfaces of reference glasses developed for the Defense Waste Processing Facility (DWPF) to characterize their corrosion behavior. The corrosion mechanism of nucIear waste glasses must be known in order to provide source terms describing radionuclide release for performance assessment calculations. Different D W F reference glasses were corroded under conditions that highlighted various aspects of the corrosion process and led to different extents of corrosion. The
more » ... corrosion. The glasses corroded by similar mechanisms, and a phenomenological description of their corrosion behavior is presented here. The initial leaching of soluble glass components results in the formation of an amorphous gel layer on the glass surface. The gel layer is a transient phase that transforms into a layer of clay crystallites, which equilibrates with the solution as corrosion continues. The cIay layer does not act as a barrier to either water penetration or glass dissolution, which continues beneath it, and may eventually separate from the glass. Solubility limits for glass components may be established by the eventual precipitation of secondary phases; thus, corrosion of the glass becomes controfled by the chemical equilibrium between the solution and the assemblage of secondary phases. In effect, the solution is an intermediate phase through which the glass transforms to an energetically more favorable assemblage of phases. Implications regarding the prediction of long-term glass corrosion behavior are discussed.
doi:10.2172/80966 fatcat:i72e4o4ikvd6pagwkwxso3yl4i