Hydrogen Production and the Stability of Hardened Cement Paste under Gamma Irradiation

Ishikawa, Shunsuke; Maruyama, Isao; Takizawa, Masayuki; Etoh, Junji; Kontani, Osamu; Sawada, Shohei

doi:10.3151/jact.17.673

Cited by 16 publications

(4 citation statements)

References 25 publications

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“…The deterioration mechanism of concrete under accelerated aging conditions is the expansion of aggregate due to density reduction through the metamictization of quartz and feldspar by neutron irradiation and cement paste shrinkage due to dehydration caused by gamma ray heating. Interested readers may refer to the results of a Japanese project investigating the deterioration of concrete (Ishikawa et al 2019;Maruyama et al , 2018Maruyama and Muto 2016).…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of a Concrete Biological Shielding Wall under Neutron Irradiation by 3D RBSM

Kambayashi

Sasano²,

Sawada

et al. 2020

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In nuclear power plants, concretes used for biological shielding walls are exposed to radiation such as neutrons and gamma rays over the long-term operation of the plant. Previous studies have reported that neutron irradiation causes aggregate expansion due to the metamictization of quartz and feldspar leading to reduced density and a loss of the compressive strength and Young's modulus of the concrete. Therefore, it is crucial to understand the current state of a concrete biological shield (CBS) and predict its future soundness. In this study, a rigid-body spring model, which can easily evaluate fracture behavior by using springs between each element, is used to conduct numerical analyses on a CBS. A three-phase (mortar, aggregate, and interfacial transition zone) model of a 2000 mm thick CBS is used to investigate the varying deformation responses depending on the presence or absence of reinforcing bars (rebar), creep, and an inner steel plate with five types of analyses, i.e. analysis to understand the impacts of temperature distribution, reinforcement bars, an internal steel plate, and creep of mortar. The results show that cracking and delamination occur inside the CBS, resulting in a lack of cracking on the outside. They also show that the cracks are reduced by rebar and creep, resulting in cracks extending from the innermost edge to a depth of approximately 150 mm.

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Section: Introductionmentioning

confidence: 99%

Numerical Analysis of a Concrete Biological Shielding Wall under Neutron Irradiation by 3D RBSM

Kambayashi

Sasano²,

Sawada

et al. 2020

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“…They were found to be between 6.1 and 3.6 × 10 -8 mol J -1 , respectively but the participation of adsorbed water in the production of radiolytic H 2 is therefore probable. Values between 3.1 and 7.3 × 10 -9 mol J -1 were obtained under γ-irradiation of cement pastes heated to 120°C, but the material was a mixture of portlandite and cementitious C-S-H (Ishikawa et al 2019). Furthermore, the temperature chosen to eliminate adsorbed water certainly affected part of the bound water in the last component.…”

Section: Introductionmentioning

confidence: 99%

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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“…Readers can refer to (Maruyama and Muto 2016;Maruyama et al , 2017Maruyama et al , 2018Ishikawa et al 2019) for understanding the project of Japanese Nuclear Regulatory Authority.…”

Section: Introductionmentioning

confidence: 99%

Meso-Scale Modelling of the Mechanical Properties of Concrete Affected by Radiation-Induced Aggregate Expansion

Sasano¹,

Maruyama

Sawada

et al. 2020

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To evaluate the radiation-induced degradation of concrete, a rigid-body spring network model is introduced that takes into account the three phases in concrete: mortar, aggregate, and the interfacial transition zone. The proposed model enables evaluation of the change in the physical properties of concrete affected by aggregate expansion under the free restraint condition. Good agreement with previous experimental data is found for the linear expansion of the concrete specimen and the compressive strength, Young's modulus, and splitting tensile strength. Based on the numerical results, it is concluded that, to reproduce the physical property changes in concrete, the expansion of mortar due to the radiation-induced expansion of fine aggregate and/or creep behavior must be considered. In addition, it is clarified that an isolated expansion of mortar with a lack of expansion in the coarse aggregate also degrades the concrete and, consequently, analysis of the type of aggregate used is critical for predicting the properties of concrete under neutron irradiation. Furthermore, the impact of inhomogeneous expansion of rock-forming minerals in coarse aggregates on physical property changes is studied, showing that such a partial expansion in the aggregates and the resultant cracks in aggregates greatly influences the reduction of the Young's modulus, with minimal impact on the reduction of compressive strength. The proposed model can be used to evaluate concrete degradation due to radiation-induced volumetric expansion of aggregate caused by the metamictization of rock-forming minerals.

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Hydrogen Production and the Stability of Hardened Cement Paste under Gamma Irradiation

Cited by 16 publications

References 25 publications

Numerical Analysis of a Concrete Biological Shielding Wall under Neutron Irradiation by 3D RBSM

Numerical Analysis of a Concrete Biological Shielding Wall under Neutron Irradiation by 3D RBSM

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

Meso-Scale Modelling of the Mechanical Properties of Concrete Affected by Radiation-Induced Aggregate Expansion

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