Sion Kim, Kamal Asghar, Miguta Faustine Ngulimi, Bum Kyoung Seo, Changhyun Roh
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引用次数: 0
Abstract
The feeder pipes of the primary cooling system in a pressurized heavy water reactor (PHWR) are composed of carbon steel SA 106 GR.B. On the surface of this structural material, corrosion oxide layers including radionuclides are formed due to the presence of active species from water decomposition products caused by radiation, as well as the high temperature and high-pressure environment. These oxide layers decrease the heat transfer efficiency of the primary cooling system and pose a risk of radiation exposure to workers and the environment during maintenance and decommissioning, making effective decontamination essential. In this study, we simulated the formation of the corrosion oxide layer on the surface of carbon steel SA 106 GR.B, characterized the formed corrosion oxide layer, and investigated the dissolution characteristics of the corrosion oxide layer using oxalic acid (OA), a commercial chemical decontamination agent. The corrosion oxide layer formed has a thickness of approximately 4 µm and consists of hematite (Fe2O3) and magnetite (Fe3O4). The carbon steel coupons with formed oxide layers were dissolved in 10 mM and 20 mM OA solutions, resulting in iron ion concentrations of 220 ppm and 276 ppm in the OA respectively. In 10 mM and 20 mM OA, the corrosion depths of the coupons were 8.93 µm and 10.22 µm, with corrosion rates of 0.39 mg/cm2·h and 0.45 mg/cm2·h, respectively. Thus, this demonstrates that higher OA concentrations lead to increased dissolution and corrosion of steel.
加压重水反应堆（PHWR）一次冷却系统的馈水管由碳钢 SA 106 GR.B 组成。在这种结构材料的表面，由于辐射造成的水分解产物中活性物种的存在以及高温高压环境，会形成包括放射性核素在内的腐蚀氧化层。这些氧化层会降低一次冷却系统的传热效率，并在维护和退役过程中对工人和环境造成辐射风险，因此必须进行有效的去污处理。在这项研究中，我们模拟了碳钢 SA 106 GR.B 表面腐蚀氧化层的形成过程，对形成的腐蚀氧化层进行了表征，并使用商业化学去污剂草酸（OA）研究了腐蚀氧化层的溶解特性。形成的腐蚀氧化层厚度约为 4 µm，由赤铁矿（Fe2O3）和磁铁矿（Fe3O4）组成。将已形成氧化层的碳钢试样溶解在 10 mM 和 20 mM OA 溶液中，OA 中的铁离子浓度分别为 220 ppm 和 276 ppm。在 10 mM 和 20 mM OA 溶液中，试样的腐蚀深度分别为 8.93 µm 和 10.22 µm，腐蚀速率分别为 0.39 mg/cm2-h 和 0.45 mg/cm2-h。因此，这表明较高的 OA 浓度会导致钢的溶解和腐蚀增加。
期刊介绍：
Carbon Letters aims to be a comprehensive journal with complete coverage of carbon materials and carbon-rich molecules. These materials range from, but are not limited to, diamond and graphite through chars, semicokes, mesophase substances, carbon fibers, carbon nanotubes, graphenes, carbon blacks, activated carbons, pyrolytic carbons, glass-like carbons, etc. Papers on the secondary production of new carbon and composite materials from the above mentioned various carbons are within the scope of the journal. Papers on organic substances, including coals, will be considered only if the research has close relation to the resulting carbon materials. Carbon Letters also seeks to keep abreast of new developments in their specialist fields and to unite in finding alternative energy solutions to current issues such as the greenhouse effect and the depletion of the ozone layer. The renewable energy basics, energy storage and conversion, solar energy, wind energy, water energy, nuclear energy, biomass energy, hydrogen production technology, and other clean energy technologies are also within the scope of the journal. Carbon Letters invites original reports of fundamental research in all branches of the theory and practice of carbon science and technology.
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