压水堆燃料包壳锆合金材料腐蚀初期行为纳米-原子尺度研究

Zirconium alloy is an important structural material used for fuel cladding in nuclear pressurized water reactor, and its waterside corrosion resistance is a key factor for service life of nuclear fuel. At present, according to the economic orientation of increasing fuel burnup and decreasing generating cost, the demand of corrosion property of fuel cladding zirconium alloys has become increasingly urged. However, some common and mechanism-based problems in corrosion behaviors of zirconium alloy has not been systematically explained, and these basic scientific items have restricted the understanding of corrosion behaviors of zirconium alloy and the design of new fuel cladding materials. This research program is focused on the anisotropy in corrosion behavior of zirconium alloy, and the object is coarse-grain (200~800 μm) Zircaloy-4 alloy. The emerging microstructure characterization techniques, such as transmission Kikuchi diffraction (TKD), 3D atom probe (3DAP) and aberration-corrected transmission electron microscopy (aberration-corrected TEM) etc., are applied in this study. This program is specified with initial corrosion behaviors to eliminate the influences from oxide film thickening, e.g. phase transformation, defect accumulation, mass transfer process alternation etc. The research program is aimed at revealing the intrinsic behaviors of grains with various crystalline orientations during initial corrosion stage and elucidating the mechanisms and effects of temperature and water chemistry on anisotropy in corrosion behaviors of zirconium alloys on nano-atomic scale.

锆合金是压水堆中用作核燃料元件包壳的重要结构材料，其耐水侧腐蚀性能是影响燃料元件服役寿命的关键因素。当前，根据提高核燃料燃耗、降低发电成本的经济性导向，对燃料包壳锆合金材料的腐蚀性能的要求日益提高。然而，锆合金的腐蚀行为中的一些共性机理问题并未得到系统阐释，这些基础性核心科学问题严重制约着对锆合金腐蚀行为的理解和新型燃料包壳材料的研发。本研究项目针对锆合金腐蚀行为中的各向异性，以大晶粒（200~800 μm）Zr-4合金为研究对象. 借助新兴的电子菊池衍射（TKD）、三维原子探针（3DAP）和球差校正透射电子显微镜（aberration-corrected TEM）等微观表征技术，从腐蚀初期行为着手，规避氧化膜增厚带来的物相变化、缺陷集聚及传质过程改变带来的影响，揭示不同晶面取向的晶粒在腐蚀初期的本征氧化行为，从纳米-原子尺度阐释锆合金腐蚀行为各向异性受温度和水化学条件影响的机理。

锆合金是压水堆中用作核燃料元件包壳的重要结构材料，其耐水侧腐蚀性能是影响燃料元件服役寿命的关键因素。然而，锆合金的腐蚀行为中的一些共性机理问题并未得到系统阐释，这些基础性核心科学问题严重制约着对锆合金腐蚀行为的理解。本研究项目以大晶粒（200~800 μm）Zr-4合金为研究对象. 探索并改进了了大晶粒锆合金的制备工艺，同时借助新兴的微观表征技术，从腐蚀初期行为着手，规避氧化膜增厚带来的物相变化、缺陷集聚及传质过程改变带来的影响，揭示了不同晶面取向的晶粒在腐蚀初期的本征氧化行为。