The effect of Cu2+ in bulk solution on pitting corrosion resistance of extra-high-purity type 316 stainless-steel was investigated. Pitting occurred in 0.1 M NaCl-1 mM CuCl2, whereas pitting was not ...initiated in 0.1 M NaCl. Although deposition of Cu2+ on the surface occurred regardless of a potential region in 0.1 M NaCl-1 mM CuCl2, Cu2+ in bulk solution had no influence on the passive film formation. The decrease in pitting corrosion resistance in 0.1 M NaCl-1 mM CuCl2 resulted from the deposited Cu or Cu compound and continuous supply of Cu2+ on the surface.
Methanogens capable of accepting electrons from Fe0 cause severe corrosion in anoxic conditions. In previous studies, all iron-corrosive methanogenic isolates were obtained from marine environments. ...However, the presence of methanogens with corrosion ability using Fe0 as an electron donor and their contribution to corrosion in freshwater systems is unknown. Therefore, to understand the role of methanogens in corrosion under anoxic conditions in a freshwater environment, we investigated the corrosion activities of methanogens in samples collected from groundwater and rivers. We enriched microorganisms that can grow with CO2/NaHCO3 and Fe0 as the sole carbon source and electron donor, respectively, in ground freshwater. Methanobacterium sp. TO1, which induces iron corrosion, was isolated from freshwater. Electrochemical analysis revealed that strain TO1 can uptake electrons from the cathode at lower than −0.61 V vs SHE and has a redox-active component with electrochemical potential different from those of other previously reported methanogens with extracellular electron transfer ability. This study indicated the corrosion risk by methanogens capable of taking up electrons from Fe0 in anoxic freshwater environments and the necessity of understanding the corrosion mechanism to contribute to risk diagnosis.
Radiolysis calculations of simulated seawater were conducted using reported data on chemical yields and chemical reaction sets to predict the effects of seawater constituents on water radiolysis. ...Hydrogen, oxygen, and hydrogen peroxide were continuously produced from simulated seawater during γ-ray irradiation. The concentration of H
2
exceeded its saturation concentration before it reached the steady-state concentration. The production behavior of these molecules was significantly promoted by the addition of bromide ions (Br
−
) because of the high reactivity of Br
−
with the hydroxyl radical, an effective hydrogen scavenger. It is also shown that the concentrations of these molecules were effectively suppressed by diluting seawater constituents by less than 1%.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
ジルコニウムの硝酸溶液中におけるγ線照射下での放射線分解水素吸収挙動 石島, 暖大; 上野, 文義; 阿部, 仁
Nihon Genshiryoku Gakkai wabun ronbunshi = Transactions of the Atomic Energy Society of Japan,
01/2017, Volume:
16, Issue:
2
Journal Article
Open access
Zirconium (Zr) has been used as a structural material at the spent nuclear fuel reprocessing plant in Japan because of its excellent corrosion resistance against nitric acid solution. However, ...radiolytic hydrogen is known to be generated in spent nuclear fuel solution. Zr is known to be highly susceptible to hydrogen embrittlement. Therefore, evaluating the radiolytic hydrogen absorption behavior of Zr in nitric acid solution (HNO3) is essential. In this study, immersion tests were conducted on Zr in nitric acid solutions under γ-ray irradiation to evaluate its radiolytic hydrogen absorption behavior. Results showed that the hydrogen concentration on Zr increased in both 1–3 mol/L HNO3 and pure water upon irradiation of 5 and 7 kGy/h after immersion. The amount of hydrogen absorption on Zr under γ-ray irradiation had a direct correlation with the amount of radiolytic hydrogen generated in HNO3. The results of glow discharge optical emission spectrometry, thermal desorption spectroscopy, and X-ray diffraction show that the absorbed radiolytic hydrogen generated a hydride on the surface of Zr.
When nuclear waste is immobilized in cement or geopolymer, gases may be generated by corrosion and radiolysis. This production must be accurately predicted, and waste loading and countermeasures ...selected accordingly to avoid overpressure and limit the risk of explosion in the case of dihydrogen (H2). We measured and simulated H2 generation and release from water-saturated geopolymer confined in a glass bottle under 60Co gamma irradiation. It was observed that confinement of H2 in the pores of a high pH geopolymer could lead to recombination of more than 99.9 % of the hydrogen generated by radiolysis. Shrinkage can allow hydrogen to diffuse between the geopolymer and the vessel, reducing the fraction of recombined H2 to 90 % at our experimental scale. We then used a model to scale up the results of our experiments. The hydrogen release of a saturated geopolymer in a standard 200 L drum is expected to be equivalent to that of a hydraulic binder containing approximately 2 % moisture. Harnessing the effects of recombination would make it possible to preserve the capacity of countermeasures such as H2 absorbers, increase the loading capacity of waste packages, and reduce the cost of nuclear waste immobilization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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