摘要
随着我国核电站在建及运行的反应堆日渐增多,乏燃料的产生、运输和储存成为核工业面临的严峻难题.对卸载出的巨量核废乏燃料,采用闭环处理循环利用,比传统深埋更加环保和安全.采用添加中子毒物的核结构材料制造相关设备和仪器,可以保障乏燃料后处理过程的运行安全.基于核工业应用要求,针对乏燃料后处理常用的 316L不锈钢、Ti35、Zr等材料添加B或者Gd的相图展开调研,结果显示B和Gd可明显提高结构材料的中子吸收效果,但B和Gd的化学性质与过渡族金属Fe,Ti,Zr等相差甚远,除α-Zr最多固溶 2.8%Gd(原子数分数)以外,B和Gd均不能大量固溶于常规金属合金体系中,强制添加势必对合金力学性能或耐蚀性能带来巨大危害.可采用团簇模型的合金设计理念,通过含B和Gd化合物相均匀析出或者复合的制造工艺以及Zr-Gd、Ti-Gd体系的多元合金化,引入互溶的中间相,增加难以固溶的元素的固溶度,以此解决中子毒物B和Gd在乏燃料后处理中的应用瓶颈.
Abstract
With the increasing number of reactors in China's nuclear power plants,the generation,transportation and stor-age of spent fuel have become a serious problem.The closed-loop treatment and recycling of the huge amount of dangerous nuclear spent fuel unloaded is more environmentally friendly and safe than traditional deep burial.Using neutron poison opti-mized structural materials to manufacture related equipment and instruments,can ensure the safe operation of spent fuel post-processing.This work investigates the phase diagram of B or Gd added to 316L stainless steel,Ti35,zirconium and other materials commonly used in spent fuel reprocessing.The results show that B and Gd can significantly improve the neutron absorption effect of structural materials,but the chemical properties of B and Gd are far different from those of transition metal.The phase diagram shows that,except for the maximum solid solution of α-Zr is 2.8at%Gd,B and Gd cannot be dissolved in conventional metal alloy sys-tems in large quantities.Forced addition is bound to bring great harm to the mechanical properties or corrosion resist-ance of the alloy.The cluster model can be adopted to increase the solid solubility of elements that are difficult to be dis-solved.Through the manufacturing process of homogeneous precipitation or recombination of B and Gd compound phases and the multi-alloying of Zr-Gd and Ti-Gd systems,the mutually soluble intermediate phases can be introduced to solve the ap-plication bottleneck of neutron poisons B and Gd in spent fuel reprocessing.
基金项目
国家自然科学基金项目(52201021)
陕西省重点研发计划项目(2021GY-249)
国防科技工业核材料创新基金项目(ICNM-2021-ZH-16)
维普
万方数据