Europium structural effect on a borosilicate glass of nuclear interest: combining experimental techniques with Reverse Monte Carlo modelling to investigate short to medium range order

摘要

In-depth understanding of the effects of actinides in borosilicate glass matrices used for nuclear waste disposal is of great importance for nuclear spent fuel reprocessing cycle and fission products immobilization. This work carried out on ternary simplified glasses (Si, B,Na) doped respectively with,1 mol. % and 3.85 mol. % europium, presents a comprehensive study on the behaviour of trivalent europium taken as a surrogate of trivalent actinides. Neutron scattering, Wide Angle X-ray Scattering, Nuclear Magnetic Resonance, Raman Spectroscopy and Reverse Monte Carlo simulations were performed. For both glasses, it was found that europium coordination number was around 6 ± 0.2,revealing an octahedral spatial configuration. Europium species accommodates in both silicate and borate site distributions but preferentially in the silicate network. Europium induces a ⅣB/ⅢB ratio decrease and a silicate network polymerization according to NMR ~(29)Si chemical shift and Raman spectra evolution.