压水堆燃料包壳锆合金中第二相腐蚀行为研究进展

Research Progress on Corrosion Behavior of Secondary Phase Precipitate of Zirconium Alloy Fuel Cladding in Pressurized Water Reactor

摘要:

锆合金是目前唯一大规模商用的压水堆燃料包壳材料,其耐水侧腐蚀性能是影响核反应堆安全性与经济性的重要因素。微量合金元素(Fe、Nb等)主要以第二相的形式弥散分布在锆合金基体中,但可对锆合金的腐蚀行为产生显著影响。本文比较了不同锆合金中第二相的差异,综述了锆合金中典型第二相的腐蚀行为及其影响因素。分别比较了二元及三元第二相中主要合金元素Fe和Nb的腐蚀过程,总结了不同水化学条件下第二相腐蚀产物的差异及其对锆合金基体腐蚀行为的影响,并指出当前针对第二相腐蚀行为研究中存在的不足。最后,对锆合金第二相腐蚀行为研究趋势进行了展望,先进微观表征手段可进一步完善含Fe、Nb元素第二相的腐蚀机理研究,将为提高我国新型锆合金包壳材料的耐腐蚀性能提供理论参考。

Abstract:

Zirconium alloy is the one and only fuel cladding material for pressurized water reactor (PWR) in full-scale commercial use at present, and its water-side corrosion resistance is the dominant factor for the safety and economy of nuclear reactor. The trace alloying elements (Fe, Nb etc.) are existed in zirconium matrix in the form of dispersive secondary phase precipitates (SPPs), which has a crucial influence on the corrosion behavior of zirconium alloy. The type of SPP for various zirconium alloys was compared in this article, and then the corrosion behaviors and influence factors of typical SPPs were reviewed. The corrosion procedures of principal alloying elements Fe and Nb within the binary and/or ternary SPPs were compared respectively, and the difference of SPP corrosion products under different water chemistry and the further effects on the corrosion behavior of zirconium matrix were also summerized. Meanwhile, the deficiencies of current studies on SPP corrosion behavior were indicated. Finally, the future research vision of SPP in zirconium alloy was enunciated herein, and advanced microstructure characterization methods will further refine the mechanism study on corrosion of SPPs bearing Fe and/or Nb, which will provide theoretical support for the corrosion resistance improvement of domestic novel zirconium cladding materials.