压水堆燃料棒UO_(2)燃料芯块与锆合金包壳化学相互作用层研究  

Chemical interaction layer between uranium oxide fuel pellet and zirconium alloy cladding in pressurized water reactor

作　　者：王华才 杨大伟 程焕林 汤琪 王玮 钱进 WANG Huacai;YANG Dawei;CHENG Huanlin;TANG Qi;WANG Wei;QIAN Jin(China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学院研究院,北京102413

出　　处：《核技术》2023年第9期103-110,共8页Nuclear Techniques

基　　金：中核集团青年英才项目(No.FY202307000520)资助。

摘　　要：反应堆运行期间,锆合金包壳与燃料接触后不断氧化,与燃料结合形成牢固的化学相互作用层,影响燃料间隙热导、包壳力学性能和燃料包壳机械相互作用。本文以压水堆核电站燃耗45 GWd·t U^(-1)完整燃料棒为研究对象,利用金相显微镜(Metallographic Microscope)、扫描电子显微镜及能谱分析(Scanning Electron Microscopy-Energy Dispersive Spectroscopy,SEM-EDS)和热室内拉曼光谱(Raman Spectroscopy)方法对其化学相互作用层形貌及结构进行分析,国内首次获得堆内辐照后包壳和芯块化学相互作用层相关分析数据。结果表明:运行至45 GWd·t U^(-1)燃耗后,燃料芯块与包壳间隙形成14~19μm的化学相互作用层,不同位置机械接触的时间顺序差异,导致作用层的不连续形成与长大。SEM-EDS结果表明,相互作用层呈“蠕虫”状形貌,且由U、Zr、O三元素构成形成混合相(U,Zr)O_(x)化合物,并且发现化学相互作用层由化学黏附和机械作用共同作用的结果。拉曼光谱显示,化学相互作用层主要由四方相氧化锆(t-ZrO_(2))和单斜相(m-ZrO_(2))相组成。[Background]During reactor operation,zirconium(Zr)alloy cladding is continuously oxidized as it gets in contact with fuel,and combines with the fuel to form a firm chemical interaction layer.This affects the thermal conductivity of the fuel gap,the mechanical properties of the cladding,and the mechanical interaction of the fuel cladding.[Purpose]This work aims to obtain relevant analytical data on the chemical interaction layer between the irradiation Zr-alloy cladding and uranium oxide(UO_(2))pellets in a pressurized water reactor(PWR).[Methods]First of all,the D13 intact fuel rod with a burnup of 45 GWd·tU^(−1) for PWRs in a nuclear power plant was chosen as UO_(2) pellets with a pellet enrichment of 4.45 wt%,and M5 Zr-alloy was used as the cladding materials.Then,a series of operations(cutting,pellet separation,inlaying,secondary cutting,inlaying,and polishing of cladding tubes)was conducted in the hot cell.The polished sample was transferred to the lead chamber and the UO_(2) fuel pellet was removed using 4 mol∙L^(−1) of nitric acid solution.The cladding tube was separated from the chemical interaction layer,and a low-speed cutter was used to cut the cladding tube to a width of 2~3 mm in the glove box.Finally,the morphology and structure of the chemical interaction layer were analyzed using metallographic microscopy,scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDS),and hot cell Raman spectroscopy.[Results]The analysis results show that the gap between the fuel pellet and cladding is approximately 14~19μm after the fuel running to a burnup of 45 GWd·tU^(−1).In the chemical interaction layer,the time sequence of mechanical contact at different locations is different,resulting in discontinuity of the interaction layer.The SEM-EDS results show that the chemical interaction layer is in the shape of"worms"composed of U,Zr,and O to form a mixed phase(U,Zr)O_(x) compound.[Conclusions]The results of this study indicate that the chemical interaction layer is mainly composed of tetra

关 键 词：压水堆核电站 完整燃料棒 化学相互作用层 化学黏附 (U Zr)O_(x)化合物 

分 类 号：TL99[核科学技术—核技术及应用]