A set of reactive chemical transport calculations was conducted with the Subsurface Transport Over Reactive Multiphases (STORM) code to evaluate the long-term performance of a representative low-activity waste glass in a shallow subsurface disposal system located on the Hanford Site. Two-dimensional simulations were run until the waste form release rates reached a quasi-stationary-state, usually after 2,000 to 4,000 yr. The primary difference between the waste form release simulations for the 2001 ILAW PA, and the simulations described herein, is the number of different materials considered. Whereas the previous PA considered only LAWABP1 glass, the current PA also describes radionuclide release from three different WTP glasses (LAWA44, LAWB45 and LAWC22), two different bulk vitrification glasses (6-tank composite and S-109), and three different grout waste forms (containing Silver Iodide, Barium Iodide and Barium Iodate. All WTP and bulk vitrification glasses perform well. However, the radionuclide release from the salt in the cast refractory surrounding the bulk vitrification waste packages is 2 to 170 times higher than the glass release rate, depending on the water recharge rate. Iodine-129 release from grouted waste forms is highly sensitive to the solubility of the iodine compound contained in the grout. The normalized iodine release rate from grout containing barium iodate is a factor of 10 higher than what the normalized release rate would be if the iodine were contained in LAWA44 glass.
Revised: November 10, 2005 |
Published: July 26, 2005