Penetration behavior of water solution containing radioactive species into dried concrete/mortar and epoxy resin materials

Sato, Isamu; Maeda, Koji; Suto, Mitsuo; Osaka, Masahiko; Usuki, Toshiyuki; Koyama, Shin-ichi

doi:10.1080/00223131.2014.963725

Cited by 3 publications

(3 citation statements)

References 6 publications

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“…Many studies have focused on Cs penetration into cement and concrete over long time durations [19,20,21,22]. This study highlights three critical factors for predicting concrete contamination by radioactive Cs not have reported: the depth of concrete carbonation, aggregate Cs adsorption, and whether the cement is exposed to water or remains dry.…”

Section: Discussionmentioning

confidence: 86%

Assessment of Radioactive Cesium Contamination in Concrete Structures near Fukushima Daiichi Nuclear Power Plant

yamada,

Arai,

Maruyama

et al. 2024

Preprint

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This study investigates the contamination of concrete by radioactive cesium released by the Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Plant accident using samples from various sites in the town of Okuma, Japan. Concrete contamination was effectively evaluated through surface dose rate measurements using Geiger-Müller tubes with shielding. Corresponding radioactivity concentrations were evaluated using an NaI scintillator in a low background environment. The contamination levels were considerably lower in areas shielded from rain compared with outdoor areas exposed to rain. Contamination within concrete can be primarily attributed to radioactive Cs enrichment in specific concrete aggregates and further influenced by carbonation of the cement paste. In non-carbonated sections, radioactive Cs was concentrated in aggregates near the surface, hindering the penetration of detection into the cement paste. Concrete samples subjected to rain exhibited reduced contamination over time. Thus, rain exposure, aggregate properties, and the degree of carbonation emerged as pivotal in predicting concrete contamination. Therefore, this study yields insights into on-site measurement methods, temporal contamination trends in the environment, and the distribution of contamination within concrete structures.

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Section: Discussionmentioning

confidence: 86%

Assessment of Radioactive Cesium Contamination in Concrete Structures near Fukushima Daiichi Nuclear Power Plant

yamada,

Arai,

Maruyama

et al. 2024

Preprint

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show abstract

“…Moreover, the simultaneous formation of C-A-S-H in equilibrium with brucite (MgðOH 2 Þ) and magnesium silicate hydrate (M-S-H) phases can further weaken the concrete and bentonite barriers matrices (i.e. increase in secondary porosity), which can facilitate various other forms of physical and chemical attack, such as the alkali-aggregate reaction, recrystallization of C-A-S-H induced by Ca 2þ leaching, carbonation, formation of salt crusts, sulphate attack, corrosion of steel containers, and ion exchange [7,[75][76][77].…”

Section: Nuclear Waste Disposal Sitesmentioning

confidence: 99%

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

et al. 2019

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Hydrated aluminosilicates were synthesized with and without aqueous heavy metals (Me), such as cobalt (Co), chromium (Cr), and zinc (Zn), by a sol-gel process at different initial molar ratios of Ca/(Si ? Al) (0.6-1.6) and Me/Si (0.0-2.0), and constant Al/Si ratio (0.05) using equilibrium-approaching experiments. The chemical composition of the reactive solutions during aluminosilicate precipitation and maturation was monitored by ICP-OES. The mineralogy, nanostructure, and chemical composition of the precipitates were studied by XRD and high-resolution TEM. At Me/Si ratios B 0.2, calcium-aluminium-silicate-hydrates (C-A-S-H) with a defect 14 Å tobermorite-like structure formed, whereas at a Me/Si ratio of 2.0, either trioctahedral Co-and Zn-smectite or amorphous Cr gels precipitated, independent of the initial Ca/(Si ? Al) ratio used for gel synthesis. The immobilization capacities for Co 2þ , Cr 3þ , and Zn 2þ by C-A-S-H, Cr gel, and trioctahedral smectite are 3-40 mg/g, 30-152 mg/g, and 122-141 mg/g, respectively. The immobilization mechanism of heavy metals is based on a combination of isomorphous substitution, interlayer cation exchange, surface (ad)sorption, and surface precipitation. In engineered systems, such as underground concrete structures and nuclear waste disposal sites, hydrated aluminosilicates should exhibit a high detoxication potential for aqueous heavy metals.

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“…In terms of important physical characteristics that affect r-Cs concrete penetration, the concrete of large structures tends to crack due to dry shrinkage, leading to deep penetration of Cs ions. Drying of concrete is also important for water suction for rapid movement of contaminated water by rainfall (Sato et al 2015). Furthermore, the staining of an outdoor concrete surface by clay dust promotes Cs adsorption.…”

Section: Factors Affecting R-cs Penetration Into Concretementioning

confidence: 99%

Field Survey of Radioactive Cesium Contamination in Concrete After the Fukushima-Daiichi Nuclear Power Station Accident

Yamada

Takeuchi

Igarashi

et al. 2019

ACT

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The Fukushima-Daiichi nuclear power station accident in East Japan in 2011 released radioactive cesium (r-Cs) into the surrounding environment. In addition to the major contamination of soil and vegetation, surrounding concrete structures have also been contaminated. Understanding the contamination characteristics is important for the decontamination or disposal of offsite and onsite concrete structures. However, r-Cs contamination of actual concrete has not been extensively investigated. In this paper, the r-Cs contamination characteristics of actual concrete are introduced on the basis of several field surveys and analysis of concrete samples taken from actual contaminated structures in the Fukushima prefecture. As no dissolution to water was detected, the surface contamination was safely removed by water-jet abrasion. However, in KCl solution, significant dissolution of r-Cs was detected. A contamination depth analysis was performed by quantitative r-Cs concentration mapping based on β-ray radiography using imaging plates. In many cases, such as roadside gutter cover plates, r-Cs was located on the surface without significant penetration into the concrete. However, in cases such as degraded concrete, deeper penetration up to several millimeters deep was observed. In cracked concrete, the r-Cs penetrated at least 10 cm, with the contamination level decreasing one order of magnitude in the first 1 cm.

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Penetration behavior of water solution containing radioactive species into dried concrete/mortar and epoxy resin materials

Cited by 3 publications

References 6 publications

Assessment of Radioactive Cesium Contamination in Concrete Structures near Fukushima Daiichi Nuclear Power Plant

Assessment of Radioactive Cesium Contamination in Concrete Structures near Fukushima Daiichi Nuclear Power Plant

Removal of heavy metals (Co, Cr, and Zn) during calcium–aluminium–silicate–hydrate and trioctahedral smectite formation

Field Survey of Radioactive Cesium Contamination in Concrete After the Fukushima-Daiichi Nuclear Power Station Accident

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