Published online by Cambridge University Press: 25 February 2011
Volatility of 137Cs and 106Ru at 600ºC over high-level waste glass in a canister is numerically analyzed. The time-dependence of normalized concentrations of each radionuclide is traced by a differential equation based on a simple model consisting of competitive forward and backward steps. It is assumed that, as time proceeds, a surface layer forms on the glass and serves as a protective barrier against volatilization. It is found that the forward rate of volatilization for 137Cs is about 140 times greater than that of 106Ru at 600ºC. The effects of the glass surface area and plenum volume on the concentration excursion inside the canister are closely estimated by the differential equation.