辐照蠕变对锆合金包壳管吸氢所致多场耦合行为的影响

本文考虑辐照效应,改进了锆合金包壳管内部的氢原子扩散-氢化物析出-热-力耦合行为的微分控制方程。根据多物理场等效积分弱形式和所建立的耦合计算方法,在FEPG软件平台编制文件,生成多场耦合计算的有限元程序,并对程序进行了验证。计算分析了辐照蠕变对锆合金包壳管堆内吸氢所致多场耦合行为演化的影响,结果表明:辐照蠕变导致包壳管内产生应力松弛,促使Mises应力显著降低,同时导致静水应力由负值转变为正值,进而影响氢原子的扩散;与不考虑辐照蠕变的结果进行对比,发现辐照蠕变会增大燃料芯块与包壳管局部接触区域的负的静水应力的绝对值及向外的静水应力梯度,导致接触区域内的氢原子浓度减小,接触区域周围的氢原子浓度增大。

Effect of Irradiation Creep on Hydrogen-pick-up Induced Multi-field Coupling Behavior in Zircaloy Cladding Tube

With the irradiation effects considered,the differential governing equations were improved for hydrogen diffusion,hydride precipitation and thermo-mechanical coupling behavior in zircaloy cladding tubes.Based on the corresponding equivalent integral weak forms for the multi-physics fields together with the developed coupling computational methods,the multi-field coupling finite element procedures were generated with the written files on FEPG platform,and they were verified.The effects of irradiation creep on the in-pile multi-field coupling behavior evolution in zircaloy cladding tubes were computed and analyzed.The results indicate that irradiation creep results in stress relaxation in the cladding tubes,which can significantly decrease the Von-Mises stresses,and simultaneous irradiation creep turns the negative hydrostatic stresses into positive ones.Compared with the results without considering irradiation creep,it can be found that irradiation creep will increase the absolute value of negative hydrostatic pressures and the outward hydrostatic stress gradients where the local mechanical interaction occurs between the fuel pellet and the cladding tube,leading to the decrease of hydrogen concentration there,and the increase of hydrogen concentration in the surrounding areas.