| 引用本文: | 宋贵康,王一,查智博,公维佳,王显宗,李金山,李中奎.乏燃料后处理用合金腐蚀行为研究进展[J].中国表面工程,2024,37(5):57~76 |
| SONG Guikang,WANG Yi,ZHA Zhibo,GONG Weijia,WANG Xianzong,LI Jinshan,LI Zhongkui.Research Progress of Alloys Used in Reprocessing Spent Nuclear Fuel and Their Corrosion Behavior[J].China Surface Engineering,2024,37(5):57~76 |
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| 摘要: |
| 核电的快速发展带来大量亟待处理的乏燃料，乏燃料后处理的前端溶解工艺与后端高放废液蒸发浓缩工艺均涉及沸腾浓硝酸的使用。其核心设备溶解器和高放废液蒸发器长期服役于强酸、强氧化性环境，合金的腐蚀损伤严重威胁其安全运行。 因此，在急需提升乏燃料后处理能力的背景下，针对乏燃料后处理用合金腐蚀行为开展综述研究，具有重要的科学和工程意义。围绕后处理用的三种典型合金：低碳不锈钢、钛合金、锆合金，分别对其腐蚀行为研究进展、影响因素以及应用在后处理领域所面临的主要挑战进行详细的分析总结。详细讨论了低碳不锈钢、钛合金和锆合金在后处理环境中的腐蚀行为及其机理。结果表明，三种合金在硝酸中对应的腐蚀速率依次呈数量级降低，锆合金的腐蚀速率低至 10-4 数量级；三种合金在硝酸中的腐蚀行为均受到硝酸温度、浓度、氧化性离子等因素的影响；不锈钢在高温、浓度高于 8 mol / L 或者存在强氧化性离子的硝酸中面临晶间腐蚀问题，钛合金存在三相腐蚀问题，锆合金则在氟化硝酸中腐蚀严重。最后，简要地展望了后处理合金需要重点开展研究的内容。 |
| 关键词: 乏燃料后处理 腐蚀 锆合金 钛合金 不锈钢 |
| DOI：10.11933/j.issn.1007-9289.20240522002 |
| 分类号:TL941 |
| 基金项目:国家自然科学基金（U2067217）；国家国防科技工业局后处理专项：后处理溶解器用耐蚀锆合金研究 |
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| Research Progress of Alloys Used in Reprocessing Spent Nuclear Fuel and Their Corrosion Behavior |
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SONG Guikang，WANG Yi，ZHA Zhibo，GONG Weijia，WANG Xianzong，LI Jinshan，LI Zhongkui
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School of Materials Science and Engineering, Northwestern Polytechnical University,Xi’an 710072 , China
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| Abstract: |
| The expansion of nuclear power necessitates the reprocessing of accumulated spent nuclear fuel urgently. Dissolvers and evaporators are critical for reprocessing spent nuclear fuel, where near-boiling concentrated nitric acid is used to dissolve solid fuel. Severely acidic and oxidative conditions during reprocessing accelerate the corrosion of structural materials, thus threatening their service life and safety. Therefore, a review of the corrosion behavior of alloys used in spent-fuel reprocessing offers high scientific and engineering value, under the background of emphasizing the urgency to develop highly corrosion-resistant alloys to enhance reprocessing capabilities. This comprehensive analysis summarizes the corrosion behaviors, influencing factors, and principal challenges associated with three typical alloys used in spent nuclear-fuel reprocessing: low-carbon stainless steel, titanium alloys, and zirconium alloys. Results indicate that the corrosion rates of low-carbon stainless steel, titanium alloys, and zirconium alloys in a nitric-acid environment decrease sequentially by orders of magnitude, with zirconium alloys exhibiting low corrosion rates in the 10-4 range. The complex conditions encountered by spent-fuel dissolvers and high-level waste evaporators, including variations in the nitric-acid concentration and temperature, and the introduction of oxidative ions from actinides, fission products, and corrosion products generated during spent-fuel dissolution affect the corrosion resistance of these materials. Increased temperature and nitric-acid concentration are detrimental to low-carbon stainless steel and zirconium alloys but are beneficial for enhancing the stability of the oxide film on titanium alloys. Oxidizing ions increase the corrosion rate of low-carbon stainless steel but promote the formation and repair of oxide films on titanium and zirconium alloys, thereby inhibiting their corrosion. Stainless steel maintains good corrosion resistance at nitric-acid concentrations below 8 mol / L; however, at higher concentrations and temperatures or in the presence of oxidizing ions, intergranular corrosion occurs because of the preferential dissolution of the passivation film at the grain boundaries. Titanium alloys exhibit excellent corrosion resistance in high-temperature, high-concentration nitric acid but demonstrate a high corrosion rate in weakly oxidizing nitric-acid vapor and condensate phases owing to insufficient Ti4+ for forming a protective TiO2 oxide film. Among the three materials, zirconium alloys indicate the lowest corrosion rate in nitric acid. However, in fluorinated nitric acid, the corrosion rate of zirconium alloys increase because of the susceptibility of their passivation film to damage. Furthermore, the potential for stress corrosion cracking in zirconium alloys must be considered. The intergranular corrosion mechanism of stainless steel, the tri-phase corrosion mechanism of titanium alloys, and the corrosion mechanism of zirconium alloys in fluorinated nitric acid are elucidated. Finally, an outlook on critical areas that require further investigation for the development of these alloys is provided. |
| Key words: spent nuclear fuel reprocessing corrosion Zr alloys Ti alloys stainless steel |
