在某些不配备加氢除氧的小型压水堆和单机功率更大的大型压水堆中可能存在燃料包壳处于富氧水质中的问题.目前大型核电站的核燃料包壳材料有ZIRLO、E110、E635、M5、N36等多种锆合金,均属于高Nb锆合金.高Nb锆合金的耐腐蚀性对水质中的溶解氧浓度非常敏感,在富氧水质中耐腐蚀性明显恶化,因此需要研发一种耐腐蚀性好、对水质中溶解氧浓度不敏感的新型锆合金包壳材料.概述了本团队研发的一种不含Nb的Zr-Sn系新型包壳材料JAZ锆合金.堆外高压釜腐蚀试验结果表明,JAZ锆合金在多种水化学环境中均表现出优异的耐腐蚀性,不仅优于Zr-Sn系的Zr-4合金,还优于商用的Zr-Nb和Zr-Sn-Nb系合金,并对水质中的溶解氧浓度不敏感.从锆合金中第二相的氧化行为、氧化膜显微组织的演化行为和氧化膜中应力的演变行为等方面揭示了腐蚀水质中溶解氧浓度对锆合金腐蚀行为的影响机制.
In certain small pressurized water reactors and large pressurized water reactors with higher single-unit power output, issues may arise with fuel cladding being exposed to oxygen-rich water conditions. Currently, the nuclear fuel cladding materials used in large nuclear power plants include various zirconium alloys, such as ZIRLO, E110, E635, M5, N36, etc., all of which are high-Nb zirconium alloys. The corrosion resistance of high-Nb zirconium alloys is highly sensitive to dissolved oxygen in water, and their corrosion resistance significantly deteriorates in oxygen-enriched water. Therefore, there is a need to develop a new type of zirconium alloy cladding material with both excellent corrosion resistance and insensitivity to dissolved oxygen. This paper provides an overview of a novel Nb-free Zr-Sn-based cladding material developed by our team, called JAZ zirconium alloy. Autoclave corrosion tests conducted out of pile show that the JAZ zirconium alloy exhibits superior corrosion resistance in various hydrochemical environments. The corrosion resistance of the JAZ zirconium alloy not only surpasses that of the Zr-4 alloy but also exceeds that of commercial Zr-Nb and Zr-Sn-Nb alloys, and it remains insensitive to the concentration of dissolved oxygen in water. The mechanism by which dissolved oxygen affects the corrosion behavior of zirconium alloys is elucidated through the analysis of the oxidation behavior of the second-phase particles, the evolution of the microstructure of the oxide film, and the stress evolution within the oxide film.
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