Abstract
Disposal in deep geological layers is the main course of action envisaged in France for the management of high-level nuclear waste, the chemical immobilization of radionuclides being ensured by the use of borosilicate glass. Over time and as groundwater permeates through the waste package s protective barriers, the glass matrix is expected to undergo chemical alteration. Simplified borosilicate glass alteration in the presence of water and self-irradiation (α, β, γ) from radionuclides has been an object of research for several decades, and it was established that energy deposition via self-irradiation increases the alteration rate and formation of an altered layer [1], [2]. The observed morphology of the altered glass layer features a structure of pores up to a few nms in diameter [2], [3], the long-term role of which is still unclear [4]. The closure of such pores under certain conditions was observed as well [5], suggesting that competing processes may be at work. Concomitantly, electron and ion irradiation of mesoporous silica such as SBA-15 and MCM-41 was recently investigated, and the collapse of the pore structure was monitored using Small-Angle X-Ray Scattering (SAXS) [6], [7]. Here we propose a novel approach to the study of borosilicate glass alteration layers via the sol-gel synthesis of an appropriate mesoporous substitute, suitable for SAXS monitoring. Since the presence or absence of water is suspected to be a determining factor [5], an experimental setup is devised to provide a wet environment while irradiating the material.[1] C. Gillet, Etude des effets de synergie entre irradiation et altération par l eau des verres nucléaires., UNIVERSITÉ DE MONTPELLIER, (2022).[2] M. Tribet et al., New Insights about the Importance of the Alteration Layer/Glass Interface, J. Phys. Chem. C, vol. 124 (2020), no 18, p. 10032.[3] S. Gin et al., A General Mechanism for Gel Layer Formation on Borosilicate Glass under Aqueous Corrosion, J. Phys. Chem. C, vol. 124 (2020), no 9, p. 5132.[4] M. Taron, Simulation à l échelle nanoscopique du transport réactif : application à la dissolution des verres nucléaires , UNIVERSITÉ DE MONTPELLIER, (2022).[5] A. H. Mir, A. Jan, J.-M. Delaye, S. Donnelly, J. Hinks, et S. Gin, Effect of decades of corrosion on the microstructure of altered glasses and their radiation stability, Npj Mater. Degrad., vol. 4 (2020), no 1, p. 11.[6] J. Lin, Radiation-induced Alterations in Mesoporous Silicas: The Effect of Electronic Processes Involving Ions and Electrons, UNIVERSITÉ DE MONTPELLIER, (2022).[7] Y. Lou, B. Siboulet, S. Dourdain, M. R. Rafiuddin, X. Deschanels, et J.-M. Delaye, Molecular dynamics simulation of ballistic effects in mesoporous silica, J. Non-Cryst. Solids, vol. 549 (2020), p. 120346.