AVM nuclear glass/steel/claystone system altered by Callovo–Oxfordian poral water with and without cement–bentonite grout at 70°C

Abstract

The effect of a cement-bentonite grout material (CBG) was studied through glass/steel interactions. Hence 2 experimental mock-ups, consisting of a "sandwich" of 4 materials in contact: stainlesssteel/AVM glass/AVM glass/P285NH steel, were leached by Callovo-Oxfordian poral water at 70°C for 1 year. CBG material was added for one experiment, whereas the second one was CBG-free. Chemical and structural analyses (SEM-EDS, Raman), performed mainly at the AVM glass/P285NH interface, evidenced a comparable alteration with and without the CBG. Indeed, its presence did not impact the gel formation by hydrolysis/condensation mechanism. For both experiments, the glass alteration rates corresponded to 0 ,70°3 2 , highlighting a kinetic rate drop after a 1-year leaching period. However, the CBG impacted the pH solution initially buffered by the claystone, promoting precipitation of Mg/Ferich silicates on the gel surface. Regarding P285NH corrosion, no major difference was observed with the CBG. Steel corrosion layers in both experiments were Si-free, and the corrosion rates were similar. Therefore, after 1 year at 70°C, the CBG had a limited effect on the glass/carbon steel interactions.

Characterization of Iron-Rich Phyllosilicates Formed at Different Fe/Si Ratios

“…Silica consumption can then lead to glass corrosion. Indeed, the study of Carriere et al (2021) identified phyllosilicate phases on the glass-steel interface.…”

“…The formation of phyllosilicates in the Fe-Si-O-H system has been reported in various geological and engineering settings: on meteorites (Elmaleh et al, 2015;Lauretta et al, 2000;Muller et al, 1979;Zolensky et al, 1993;Zolotov, 2014), on Mars (Bishop et al, 2008;Ehlmann et al, 2011), in deep-sea sediments (Badaut et al, 1985(Badaut et al, , 1992Baldermann et al, 2015;Marcus & Lam, 2014), in iron-banded formations (Eugster & Chou, 1973;Grubb, 1971), in ore deposits (Inoué & Kogure, 2016;Rasmussen et al, 1998;Rivas-Sanchez et al, 2006), at iron-clay (Lanson et al, 2012;Le Pape et al, 2015;Pignatelli et al, 2014) and steel-glass interfaces (Carriere et al, 2017(Carriere et al, , 2021Schlegel et al, 2016), and as a scale deposit in brinehandling equipment (Manceau et al, 1995). Thermodynamic modeling for some of these settings has been performed with the intention of estimating the physicochemical conditions which led to the formation of these minerals in the past (Chevrier et al, 2007;Fritz & Toth, 1997;Zolotov, 2014), or of estimating the evolution of physicochemical conditions for a given mineralogical composition with time (Ngo et al, 2015;Wilson et al, 2015).…”

“…First, for some settings such as iron-glass interfaces, the identification of newly-formed minerals is rather arduous due to their very small particle size. The thickness of the alteration layer between iron and glass is in the range of 1 µm (Carriere et al, 2017(Carriere et al, , 2021Schlegel et al, 2016). Second, the information regarding experimentally measured thermodynamic properties of iron-rich minerals is very limited.…”

“Impact of γ-radiation on carbon steel anaerobic corrosion and H2 production.”

“…Due to the progressive glass alteration process, the use of glass beaker and glass sample holder may induce ion-exchange mechanisms between silicon and iron ions [44][45][46]. We thus decided to perform additional post-mortem analysis on these glass elements.…”