Development and characterization of rare earth-rich glassy matrices envisaged for the immobilization of concentrated nuclear waste solutions

New nuclear highly durable glass compositions, able to immobilize a higher concentration of high-level nuclear wastes than current borosilicate nuclear glasses, are being studied Investigations are performed on rare earth (RE)-rich glasses, known as durable matrices. After a preliminary study on complex and simplified compositions, a basic glass composition was selected and studied (wt%): 51.0 SiO2-8.5 B2O3-12.2Na(2)O-4.3Al(2)O(3)-4.8CaO-3.2ZrO(2)-16.0RE(2)O(3). Chemical durability, physical properties (viscosity, transformation temperature), and crystallization tendency of glasses containing either a mixture of RE (La + Ce + Pr + Nd) or only one RE were studied and compared The local environment of RE (for RE = Nd) in the glass and its evolution according to Nd2O3 concentration (from 1.3 to 30 wt%) was also studied by coupling characterization methods such as extended X-ray absorption fine structure spectroscopy at the neodymium L-111-edge and optical absorption spectroscopy. B-11, Al-27 magic angle spinning-nuclear magnetic resonance, and Raman spectroscopy were also used to study glass structure.