Apparent solubility limit of nuclear glass

Most nuclear glass alteration models are based on a first-order kinetic law of the general type r = r0(l-Csi/C*) or r = r0(l-Q/K). It is generally assumed that the establishment of quasi steady-state concentrations in solution corresponds to an intrinsic glass solubility limit that may be expressed either in terms of the dissolved silicon concentration C* or as an ion activity product at saturation K. Experimental research over the last five years in France has shown that the quasi steady-state concentrations observed in solution do not correspond to a thermodynamic solubility limit with respect to the glass. This assertion is supported by a large body of experimental evidence that is discussed in this paper. The signification of the C* parameter is therefore reconsidered, and its implications on long-term behavior modeling are discussed. Copyright (2001) Material Research Society