大破口失水事故工况下碳化硅惰性氧化模型研究  

Theoretical Research on Passive Oxidation Model of Silicon Carbide under Large Break Loss of Coolant Accident Condition

作　　者：钱立波[1] 余红星[1] 孙玉发[1] 陈伟[1] 申亚欧[1] QIAN Libo;YU Hongxing;SUN Yufa;CHEN Wei;SHEN Yaou(Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610041,China)

机构地区：[1]中国核动力研究设计院核反应堆系统设计技术重点实验室

出　　处：《原子能科学技术》2019年第7期1280-1287,共8页Atomic Energy Science and Technology

基　　金：国家自然科学基金资助项目(11705189)

摘　　要：与传统Zr包壳相比,SiC复合包壳具有更好的辐照稳定性、高温机械性能和抗氧化能力,可有效缓解事故进程,增加事故应对时间。在大破口失水事故工况下,SiC复合包壳会与低压高温水蒸气发生惰性氧化反应而持续损耗。SiC材料的惰性氧化反应分为两个过程:SiC抛物线型氧化过程和SiC表面氧化产生的SiO 2的线性挥发过程。本文应用修正的Deal-Grove模型和传热/传质类比法研究SiC的抛物线型氧化速率和SiO 2的线性挥发速率,并基于纯水蒸气环境下SiC氧化实验数据和SiO 2线性挥发实验数据,获得了SiC抛物线型氧化速率常数模型和SiO 2线性挥发速率常数模型。理论模型分析结果显示,在大破口失水事故后低压高温纯水蒸气氧化条件下,SiC材料的氧化速率常数较Zr合金低约2~3个数量级,导致SiC材料的损耗速率远低于传统Zr包壳的损耗速率。Comparing with conventional Zr-cladding, SiC composite cladding is expected to slow down accident progression and provide wider margin of coping time by virtue of better radiation resistance, retention of higher strength up to very high temperatures and better oxidation resistance. Under large break loss of coolant accident (LB LOCA ), the recession of SiC composite cladding would continue due to the passive oxidation of SiC with low-pressure and high-temperature steam, which consists of two phases: The parabolic oxidation of SiC and subsequent linear volatilization of silica formed on the surface of SiC. In present paper, the modified Deal-Grove model and heat/mass transfer analogy method were utilized to study the SiC parabolic oxidation and SiO 2 linear volatilization rate on the basis of SiC oxidation and SiO 2 volatilization experimental data under pure steam conditions, respectively. Obtained theoretical model shows that under post-LB LOCA low-pressure and high-temperature pure steam oxidation condition, the oxidation rate of SiC is significantly slower than that of Zr (2-3 orders of magnitudes), which results in much less material recession rate of SiC than that of zirconium.

关 键 词：大破口失水事故 碳化硅 惰性氧化 

分 类 号：TL333[核科学技术—核技术及应用]