乏燃料贮存环境中Al-B4C复合材料的腐蚀行为研究

Corrosion Behavior of Al-B_4C Composite in Spent Nuclear Fuel Storage Environments

通过实验室环境模拟沸水堆(BWR)和压水堆(PWR)乏燃料的贮存环境对不同表面处理试样开展全浸腐蚀实验。采用SEM和EDS观测腐蚀微观形貌和分析腐蚀产物,采用XRD测试腐蚀试样的物相,并通过测试试样干重得到腐蚀动力学曲线。结果表明,材料中的Al和微量元素Mg,Fe是引起腐蚀的主要因素;抛光处理试样在PWR贮存液中时,因Fe的影响出现4种微观腐蚀形貌,耐蚀性较差,而在BWR贮存液中时生成Al(OH)3保护膜,耐蚀性较好;阳极氧化处理试样在PWR和BWR贮存液中均腐蚀增重,腐蚀产物能封闭氧化膜孔洞,抗腐蚀性能最好。

Al-B,C composite is a candidate material of neutron absorption for spent nuclear fuel storage racks. The corrosion behavior of Al-B4C composite with different surface pre-treatments was examined by immersion test in solutions simulated the pressure water reactor （PWR） and boiling water reactor （BWR） spent nuclear fuel storage environments. Then the surface morphology of the corroded samples was observed by SEM, the elemental distribution and the phase constituent of corrosion products were characterized by EDS and XRD respectively. The results showed that the composite was corroded due to the preferential corrosion of A1 and trace elements such as Mg and Fe. After immersion in PWR spent nuclear fuel storage solution, four different corrosion morphologies on the polished sample could be differentiated showing a poor corrosion resistance, which might be related with the Fe distribution in the composite. However, after immersion in BWR storage solution an AI（OH）3 film formed on the polished sample surface indicating a good corrosion resistance. The pre-anodized samples exhibited mass gain after immersion test in the two storage solutions of PWR and BWR respectively, indicating the best corrosion resistance, which may be due to that the pores of the anodized film was sealed by the formed corrosion products in the solutions.