Simulation of the fracture behavior of Zircaloy-4 cladding under reactivity-initiated accident conditions with a damage mechanics model combined with fuel performance codes FEMAXI-7 and RANNS

A continuum damage mechanics model using FEM calculations was proposed to be applied to an analysis of the fuel failure due to pellet cladding mechanical interaction (PCMI) under reactivity-initiated accident conditions. The model expressed ductile fracture via two processes: damage nucleation related to void nucleation and damage evolution related to void growth and linkage. The boundary conditions for the simulations were input from the fuel performance codes FEMAXI-7 and RANNS. The simulation made reasonable predictions for the cladding hoop strain at failure and reproduced the typical fracture behavior of the fuel cladding under the PCMI loading, characterized by a ductile shear zone in the inner region of the cladding wall. It was shown that occurrence of a through-wall crack is determined at an early stage of crack propagation, and the rest of the through-wall penetration process is achieved with a negligible increment in strain. The effect of a local temperature rise in the cladding inner region on the failure strain was found to be less than 5% for the conditions investigated. Failure strains predicted under a plane strain loading were smaller by 20%–30% than those predicted under equibiaxial tensions between the hoop and the axial directions.     

熔化情况下Zr_(-4)合金包壳管氧化膜厚度变化的计算

已有的研究表明,温度超过元件包壳熔点时,Zr-4合金与蒸汽在包壳表层反应所生成的ZrO_2氧化膜将对Zr-4合金熔融物本身起到一定的保护作用。因此这层氧化膜的厚度及完整性对于由堆芯元件过热及由此引起的Zr-4合金熔融物流动所导致的反应堆事故具有重要的影响。本文假定氧的扩散是ZrO_2氧化膜厚度变化的控制因素,通过解扩散方程,导出了对在这种情况下ZrO_2膜厚度变化的计算公式。     

水冷动力堆燃料元件包壳的水侧腐蚀

从反应堆运行工况及材料因素,讨论了水堆燃料元件包壳的水侧腐蚀问题。为满足高性能燃料元件的要求,包壳的水侧腐蚀性能需要改善。本文根据最近的一些研究结果,讨论了各种可能有效的措施。     

核反应堆用锆材的发展趋势与对策探讨

本文综述核材料锆合金的发展概况及上海与国内外先进水平的主要差距。核电的发展要求沪产锆合金管进一步改善耐高温高压水腐蚀、提高高温强度和抵抗疲劳破损的能力。为此,文中着重讨论了管材的堆内行为、组织性能与生产工艺的关系,并在此基础上研讨振兴上海锆工业的策略。     

Formation of self-organized Zircaloy-4 oxide nanotubes in organic viscous electrolyte via anodization

This work reports the formation of self-organized Zircaloy-4 (Zr-4) oxide nanotubes in viscous organic ethylene glycol (EG) electrolyte containing a small amount of fluoride salt and deionized (DI) water via an electrochemical anodization. The structure, morphology, and composition of the Zr-4 oxide nanotubes were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), EDX, and XPS. SEM results showed that the length of the nanotubes is approximately 13 μm, and TEM results showed that the inner diameter of the Zr-4 oxide nanotubes is approximately 20 nm with average wall thickness of approximately 7 nm. XRD and selected area electron diffraction pattern (SAED) results confirmed that the as-anodized Zr-4 oxide nanotubes have cubic crystalline structure. Both cubic and monoclinic phases were found after annealing of Zr-4 oxide nanotubes. The tubular structure morphology of Zr-4 oxide nanotubes did not remain intact after annealing which is attributed to the elimination of F species from the annealed nanotubes.     

压水堆燃料棒锆-4包壳在大破口LOCA条件下的鼓胀爆破实验

研制成ＦＲＳ－２型压水堆锆－４包壳电加热模拟燃料棒，提供一种先进的实验方法和瞬态测量技术，目的在于研究锆－４包壳在大破口ＬＯＣＡ条件下的鼓胀爆破行为，给出秦山核电厂安全分析所需的爆破数据。报道了模拟燃料棒的结构、性能、包壳鼓胀爆破实验方法和破口检验内容。     

反应堆冷却剂部分丧失时燃料包壳完整性分析方法

本文介绍了冷却剂部分丧失时压水堆燃料包壳完整性分析方法,提出了关于包壳腐蚀与吸氢、包壳强度、包壳瞬时坍塌与蠕变坍塌的判定准则与分析模型,并给出了后两个分析模型的验证结果。     

Methods of quantitative matrix analysis of Zircaloy-2

The zirconium-based alloy Zircaloy-2 contains small amounts of iron, chromium and nickel dissolved in the matrix. Several attempts to measure these amounts have been made in the past, but the results are conflicting and inconclusive. The advent of wide angle, laser pulsed atom probe tomography motivates a new attempt to analyze the matrix. Large datasets are now easily obtained using laser pulsing but quantification is not straightforward due to rather complex mass spectra. Zircaloy-2 contains about 1 wt% tin, 0.1 wt% oxygen and trace amounts of Si, C and Al. Severe overlaps make quantification of any Fe⁺, Cr⁺ and Ni⁺ ions impossible. Quantification of Fe, Cr and Ni therefore requires that they appear as doubly charged ions only, and consequently the field must be kept high enough. In addition, adsorbed CO⁺ may appear at the main peak of Fe²⁺. In the paper a method is reported, which gives what we believe an accurate quantitative analysis of at least iron and chromium in the matrix.     

锆合金管材在氢氧化锂溶液中的吸氢研究

研究了锆２、锆－４合金管材在高压釜内氢氧化锂溶液中,于３６０℃、１８．６ＭＰａ条件下进行不同时间的渗氢后试样的吸氢特性。试样的吸氢变化具有锆合金氧化增重类型的特点,即势力的线型的变化和转折点。另外还显示了氢氧化锂溶液的浓度对吸氢量有明显的影响。