Self-Diffusion of <SUP>22</SUP>Na and <SUP>137</SUP>Cs in Simulated Nuclear Waste Glass

Abstract

The knowledge of self-diffusion of various elements is important for understanding and elucidating the long-term dissolution of the nuclear waste glass. The self-diffusion coefficients of Na and Cs in P0798 simulated nuclear waste glass have been measured by an ion beam sputter-sectioning technique using the radioactive isotopes 22 Na and 137 Cs. The temperature dependence of the diffusion coefficients in each temperature range in P0798 glass below the glass transition temperature T g can be expressed by the following equations:The diffusion coefficient of 22 Na was about ten orders of magnitude larger than that of 137 Cs at 573 K. The large difference in the diffusion coefficients is explained in terms of the ion size effect, the mixed-alkali effect and lower concentration of Cs compared with Na in P0798 glass.

Ion-Exchange Interdiffusion Model with Potential Application to Long-Term Nuclear Waste Glass Performance

“…The values of the activation energies derived in this work match well with values reported in the industrial ion-exchange literature. The exact activation energies for ion exchange with between glass and molten salts vary depending on the ions in question and the glass composition but generally range from 100 to 150 kJ/mol. , An experiment using the Japanese P0798 simulant nuclear waste glass and a molten salt Na source also yielded a Na–Na activation energy of 113 kJ/mol; however, the absolute diffusion coefficient given in that study was 2 orders of magnitude lower than the diffusion coefficients obtained in the present study. The reason for the difference in activation energies is unknown but may be attributed to the use of Na + as the source species and not the smaller Li + species.…”

Effect of barium on diffusion of sodium in borosilicate glass

“…Diffusion in borosilicate glasses has been studied using various methods, such as, radiotracer method [3], concentration couple method [4], Rutherford backscattering spectrometry (RBS) [5] and heterogeneous isotopic exchange method [6]. In the radiotracer method the radiotracer is deposited on one surface of the sample which is then annealed at a specific temperature.…”

Effects of shear and walls on the diffusion of colloids in microchannels

“…Most current applications concern dilute systems using particles as tracers or scavengers [40,41], but the flow of concentrated colloidal fluids through microchannels (e.g., in filtration or after on-chip synthesis) is emerging. Other practical scenarios where the diffusive behavior of particles plays a role are drug delivery [42], the operation of semisolid flow batteries [43], the handling of nuclear waste [44], and stagnant or slowly moving slurries of clay or sand particles in geological rock formations [45].…”