大晶粒UO_(2)芯块及包壳涂层对燃料棒设计准则的影响分析  

The impact of large-grained UO_(2) pellet and coated zirconium cladding on design criteria for PWR fuel rod

作　　者：尤䶮 龚辛 李聪 YOU Yan;GONG Xin;LI Cong(Shanghai Nuclear Engineering Research&Design Institute Co.,Ltd,Shanghai 200233,China)

机构地区：[1]上海核工程研究设计院有限公司,上海200233

出　　处：《核技术》2021年第11期91-98,共8页Nuclear Techniques

基　　金：国家重点研发计划(No.2019YFB1901000);上海市浦江人才计划(No.19pj1431600)资助。

摘　　要：大晶粒UO_(2)芯块及锆合金包壳涂层是耐事故燃料(Accident Tolerant Fuel,ATF)中最接近实用化的燃料芯块和包壳材料方案,有望在未来几年实现商用。然而,现有商业压水堆的燃料棒设计准则都是针对使用传统UO_(2)芯块和锆合金包壳的材料特性及应用经验而制定,如果组成材料特性发生变更则有必要在相应研究的基础上重新考察设计准则的可用性。本文根据现有大晶粒UO_(2)芯块、锆合金包壳涂层的材料特性研究数据,分析了基于这两种材料方案的ATF燃料棒对燃料棒设计准则的影响。结果表明:这种ATF燃料棒的设计准则大部分可沿用现役水堆的燃料棒设计准则,燃料棒在氧化、氢化等方面都有一定的性能提升,并提高了相应设计裕量。但新增的包壳涂层将引入由涂层加工损伤及涂层破损失效等引起的导致燃料棒失效的潜在机制,包括冷喷涂等涂层制备工艺可能因损伤锆包壳基体而引起包壳疲劳性能下降、包壳涂层破损后的局部氧化等。针对这些新现象,有必要开展进一步的研究工作,据此完善相应的设计准则。[Background]Large-grained UO_(2) pellet and coated zirconium cladding are the most practical fuel pellet and cladding material scheme for accident tolerant fuel(ATF)solutions,which are expected to be commercially available in the next few years.However,the existing fuel rod design criteria for commercial pressurized water reactor(PWRs)are based on the material characteristics and application experience of traditional UO_(2) pellets and zirconium alloy cladding.If the properties of the constituent material of fuel rod change,it is necessary to re-examine the usability of the design criteria based on the corresponding research results.[Purpose]The study aims to clarify the potential problems of large-grained UO_(2) pellet and coated zirconium cladding through the fuel rod design standards,and to provide a reference for the follow-up materials testing.[Methods]Based on these two material schemes for ATF on the design criteria,latest research on the material properties of large-grained UO_(2) pellet and coated zirconium cladding were investigated,and the influence of new ATF fuel rod based on these two schemes on fuel rod design criteria was analyzed.[Results]The results show that most of the design standards can still be used,and the new ATF fuel rods have certain performance improvements in oxidation and hydrogenation,hence the corresponding design margin is increased.However,the newly added cladding coating may introduce new fuel rod failure mechanisms,including cold spraying and some other coating processes that may damage the zirconium substrate and cause a significant decrease in the fatigue performance,local oxidation after coating damage,etc.Due to the influence of the cladding coating,the equivalent cladding reacted coefficient(ECR)originally used to evaluate the embrittlement level of zirconium alloy cladding is no longer applicable.[Conclusion]Therefore,in view of these new phenomena,it is necessary to carry out further research work and improve the corresponding design criteria accordingly.

关 键 词：耐事故燃料 设计准则 燃料棒 锆包壳涂层 

分 类 号：TL352[核科学技术—核技术及应用]