烧结气氛对MOX燃料芯块性能的影响  

Effect of sintering atmosphere on the performance of MOX fuel pellet

作　　者：朱桐宇[1] 杨廷贵[1] 王军平 屠振华 张万德 ZHU Tongyu;YANG Tinggui;WANG Junping;TU Zhenhua;ZHANG Wande(The 404 Company Limited,China National Nuclear Corporation,Lanzhou 732850,China)

机构地区：[1]中核四〇四有限公司,兰州732850

出　　处：《核技术》2020年第11期90-94,共5页Nuclear Techniques

摘　　要：铀钚混合氧化物(Mixed Oxide,MOX)燃料主要应用于快堆(Fast Reactor,FBR)和压水堆(Pressurized Water Reactor,PWR),也有少量应用于沸水堆(Boiling Water Reactor,BWR),MOX燃料元件制造是“核燃料闭式循环”的重要环节。将混合均匀的铀钚氧化物粉末烧结成满足性能要求的燃料芯块是MOX燃料制造的关键工艺环节,烧结温度、保温时间及烧结气氛是影响烧结芯块致密性、氧金属比和微观结构等芯块性能指标的关键因素。针对采用机械混合法处理的二氧化铀和二氧化钚混合粉末经压制成型后得到的生坯开展烧结实验,实验中将同一处理工艺得到的同一批生坯在1700℃高温烧结炉中烧制6 h,然后缓慢还原至室温,用金相显微镜对MOX烧结芯块样品的微观结构进行分析,结果表明:在烧结温度和保温时间保持不变的基础上,随着烧结气氛中水含量的增高,芯块的致密性和氧金属比(O/M)比值增加。当烧结气氛中水含量增大到一定比例时,芯块的微观组织中的微裂纹和相分离现象逐渐消失;当烧结气氛中水含量大于1600 ppm时,得到的烧结芯块组织均匀,没有微裂纹,芯块性能指标符合快堆MOX燃料芯块技术要求。[Background]The mixed oxide fuel of uranium and plutonium(MOX fuel)is mainly used in fast reactor(FBR)and pressurized water reactor(PWR),and a small amount of MOX fuel is used in boiling water reactor(BWR).The MOX fuel manufacturing is the key link of"nuclear fuel closed cycle"whilst the key process of MOX fuel manufacturing is to sinter the fully mixed uranium plutonium oxide powder into the sintering pellets which meet the performance requirements.Sintering temperature,insulation time and sintering atmosphere are the key factors that affect the densification,the oxygen metal ratio and the microstructure of sintering pellet,etc.[Purpose]This study aims to investigate the influence of sintering atmosphere on the properties of pellets.[Methods]PuO2 powder was pretreated and mixed with UO2 powder in a certain proportion.The mixed powder was ground and granulated to form green body by two-way pressing.The same batch of green samples obtained by the same treatment process were fired in a high-temperature sintering furnace at 1700℃for 6 h,and then slowly reduced to room temperature.The microstructure of MOX fuel pellet was observed and analyzed by metallurgical microscope.The effect of the different water content on the properties of pellets in hydrogen argon mixture sintering atmosphere was studied experimentally.[Results]Experimental results show that the compactness and the O/M ratio of MOX sintered pellets increases with the increasing of water content in sintering atmosphere when the sintering temperature and holding time remain unchanged.When the water content in sintering atmosphere is more than 1600 ppm,the obtained stoichiometric MOX sintered pellets have uniform microstructure without microcracks.[Conclusions]The sintering process conforms to the theory of vacancy diffusion mechanism.

关 键 词：MOX燃料 燃料芯块 烧结气氛 芯块性能 

分 类 号：TL352.21[核科学技术—核技术及应用]