压水堆燃料元件在运行初期,由于燃料芯块的密实效应和燃料芯块与包壳之间的机械相互作用,在外压作用下,径向发生缓慢变形,造成包壳椭圆度增大,甚至引起包壳失稳倒塌。因此,研究在外压作用下不同原始椭圆度对包壳径向变形速率的影响将有一 Due to the compact effect of the fuel pellets and the mechanical interaction between the fuel pellets and the cladding, pressurized water reactor fuel elements undergo slow deformation in the radial direction under the action of external pressure during the initial operation, resulting in an increase in the ovality of the cladding and even Caused the collapse of the cladding collapse. Therefore, under the action of external pressure, the influence of different original ovality on the radial deformation rate of the cladding will have a