Production of H2 by water radiolysis in cement paste under electron irradiation: A joint experimental and theoretical study

Caër, Sophie Le; Dézerald, Lucile; Boukari, Khaoula; Lainé, Maxime; Taupin, Sébastien; Kavanagh, R.; Johnston, Conrad; Foy, Eddy; Charpentier, Thibault; Krakowiak, Konrad J.; Pellenq, Roland J.‐M.; Ulm, Franz Josef; Tribello, Gareth A.; Kohanoff, Jorge; Saúl, Andrés

doi:10.1016/j.cemconres.2017.05.022

Cited by 16 publications

(6 citation statements)

References 61 publications

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“…A similar situation was observed for tobermorite-11 in Ref. [23]. While the Ca/Si (C/S) ratio of this material (C/S = 0.7 − 0.8) is significantly lower than experimental values determined for typical C-S-H gels (C/S = 1.8) [26] and than the one obtained for the present model (C/S = 1.64) [5], it appears that the results for electron localization are remarkably independent on the C/S ratio.…”

Section: Chemical Effects: Electrons and Holessupporting

confidence: 84%

“…Knowing where exactly in the cement matrix will electrons and holes localize is important to assess the chemical and structural stability of the cement upon irradiation. These species participate in chemical reactions leading, e.g., to the production of H 2 from water dissociation [23]. The accumulation of H 2 is undesirable, especially when cement is used as a container for nuclear waste decommissioning, as it can build up pressure and lead to fracture and hence leakage of radioactive material into the soil and ground waters.…”

Section: Chemical Effects: Electrons and Holesmentioning

confidence: 99%

“…For the hole localization, there are significant differences between models. For example, considering two variants of tobermorite-11, it has been observed that holes localize on the intralayer or interlayer SiO 4 oxygens depending on the C/S ratio [23]. Holes localized in the intralayer space are unlikely to be involved in further reactions.…”

Section: Chemical Effects: Electrons and Holesmentioning

confidence: 99%

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Radioactive decay of $$\mathrm {{}^{90}Sr}$$ in cement: a non-equilibrium first-principles investigation

et al. 2021

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Cement is an inexpensive and relatively easily manageable material that is used as a last barrier for nuclear waste disposal. Under these conditions, the cement is in contact with low radiation doses, but there is a distinct possibility of being contaminated with radioactive products. Of particular concern is the medium lived half-life product $$\mathrm {{}^{90}Sr}$$ 90 Sr (28.8 years) due to its ability to replace Ca. $$\mathrm {{}^{90}Sr}$$ 90 Sr undergoes $$\beta $$ β -decay to $$\mathrm {{}^{90}Y}$$ 90 Y which, in turn, $$\beta $$ β -decays to stable $$\mathrm {{}^{90}Zr}$$ 90 Zr . In this work, we discuss systematically the chain of non-equilibrium processes that result as a consequence of $$\beta $$ β -decay events in cement. We first use density functional-based methods to study the consequences of the sudden increase of the nuclear charge from $$Z$$ Z to $$Z+1$$ Z + 1 , a possible induced ionization and the perturbation of the surrounding electronic charge. Secondly, we use molecular dynamics simulations to study the recoil of the daughter nucleus. Finally, we discuss the damage caused by the ionization cascade produced during the propagation of the $$\beta $$ β -electron and the resulting chemical and structural perturbation. Graphic Abstract

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Section: Chemical Effects: Electrons and Holessupporting

confidence: 84%

Section: Chemical Effects: Electrons and Holesmentioning

confidence: 99%

Section: Chemical Effects: Electrons and Holesmentioning

confidence: 99%

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Radioactive decay of $$\mathrm {{}^{90}Sr}$$ in cement: a non-equilibrium first-principles investigation

et al. 2021

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“…It leads to significant hydrolysis [59], in cement pores and-to a lesser extent-in the interlayer, which could affect mechanical, chemical, and transport properties of the paste. The methods presented here, including semigrand canonical Monte Carlo, ARTn, and mesoscopic models could be coupled to electronic structure calculations to further characterize the properties of C-S-H grains under such irradiation.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamics, kinetics, and mechanics of cesium sorption in cement paste: A multiscale assessment

Arayro

Dufresne

Zhou

et al. 2018

Phys. Rev. Materials

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Cesium-137 is a common radioactive byproduct found in nuclear spent fuel. Given its 30 year half life, its interactions with potential storage materials-such as cement paste-is of crucial importance. In this paper, simulations are used to establish the interaction of calcium silicate hydrates (C-S-H)-the main binding phase of cement paste-with Cs at the nano-and mesoscale. Different C-S-H compositions are explored, including a range of Ca/Si ratios from 1.0 to 2.0. These calculations are based on a set of 150 atomistic models, which qualitatively and quantitatively reproduce a number of experimentally measured features of C-S-H-within limits intrinsic to the approximations imposed by classical molecular dynamics and the steps followed when building the models. A procedure where hydrated Ca 2+ ions are swapped for Cs 1+ ions shows that Cs adsorption in the C-S-H interlayer is preferred to Cs adsorption at the nanopore surface when Cs concentrations are lower than 0.19 Mol/kg. Interlayer sorption decreases as the Ca/Si ratio increases. The activation relaxation technique nouveau is used to access timescales out of the reach of traditional molecular dynamics (MD). It indicates that characteristic diffusion time for Cs 1+ in the C-S-H interlayer is on the order of a few hours. Cs uptake in the interlayer has little impact on the elastic response of C-S-H. It leads to swelling of the C-S-H grains, but mesoscale calculations that access length scales out of the range of MD indicate that this leads to practically negligible expansive pressures for Cs concentrations relevant to nuclear waste repositories.

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“…The overall production of H 2 by Portland cement pastes with or without the addition of ground quartz was also investigated under electron irradiation. (Le Caër et al 2017). Globally, the apparent yield of H 2 was shown to increase with relative humidity, i.e., with the quantity of "free" water.…”

Section: Introductionmentioning

confidence: 93%

Contribution of the Tricalcium Silicate Hydration Products to the Formation of Radiolytic H<sub>2</sub>: A Systemic Approach

Bouniol

2022

ACT

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Because they contain residual water, cementitious materials produce radiolytic dihydrogen under irradiation, which can pose a safety concern for some nuclear applications. The estimation of H 2 emissions by current models takes into account the contribution of pore water but not that of solid hydrates, which is considered negligible. Gamma irradiation (dose rate of 359 Gy h -1 up to 6 months in a closed system under Ar gas) of hydrated tricalcium silicate pastes, the main constituent of Portland cement, shows however an initial contribution of solid hydrates to H 2 formation. A systemic study combining the source term of solid hydrates and the pore water radiolysis using simulation shows that the primary radiolytic yield devoted to portlandite and cementitious C-S-H (together) is of the order of 2.8 × 10 -8 mol J -1 , and that the contribution of the solid phases is decreasing and becomes negligible in the long term, suggesting a saturation effect with dose. Even if limited in time, the effect of the additional H 2 source term is very sensitive on the radiolysis of the pore water with the very strong solicitation of the recycling reaction chain (equivalent to the Allen chain in basic medium) and leads to a frankly reducing medium (Eh ≈ − 470 mV NHE).

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Production of H2 by water radiolysis in cement paste under electron irradiation: A joint experimental and theoretical study

Cited by 16 publications

References 61 publications

Radioactive decay of $$\mathrm {{}^{90}Sr}$$ in cement: a non-equilibrium first-principles investigation

Radioactive decay of $$\mathrm {{}^{90}Sr}$$ in cement: a non-equilibrium first-principles investigation

Thermodynamics, kinetics, and mechanics of cesium sorption in cement paste: A multiscale assessment

Contribution of the Tricalcium Silicate Hydration Products to the Formation of Radiolytic H<sub>2</sub>: A Systemic Approach

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