Ion Irradiation Induced Leaching Property Changes of Borosilicate Glass

In the process of deep geological disposal of high-level radioactive waste, the strong radiation field caused by the decay of radionuclides can lead to the leaching property changes of the waste glass. In this work, the 15 MeV Si ion irradiation was used to simulate the strong radiation field of deep geological disposal. The samples were immersed for 1, 3, 7, 14, and 28 days in KOH solution with pH=9.0 by using the MCC-1 method, respectively. The leaching behavior of the borosilicate glass before and after irradiation was studied by inductively coupled plasma emission spectrometer, Raman spectrometer and scanning electron microscope. It is observed that the leached glass surfaces occur constantly corrode and fall off with the increase of leaching time. The leaching rate of the irradiated glass samples is significantly higher than that of the unirradiated glass samples. Although it is observed that the thickness of altered layer is increased after irradiation, there are no significant difference in the structure and element composition of the altered layer between the unirradiated glass and the irradiated glass. The sodium and boron elements in the formed altered layer are basically depleted. The SiO₂ network structure in the altered layer is dissolved, a large number of Si—OH bonds and borosilicate structures are created, and the transformation from four-coordinated boron units to three-coordinated boron units is also observed.