Study on the Creep Deformation Characteristics of the Cylindrical Tubes under External Pressure

Abstract

Cylindrical tubes are fundamental structural components across many engineering fields, particularly for bearing external loads. In pressurized water reactors (PWR), the metal cladding tube acts as the first safety barrier, containing radioactive materials under extreme conditions of external pressure, high temperature, and intense fast neutron flux. Accurate prediction of its creep deformation remains a critical challenge in nuclear engineering. This study analyzes the coupled thermal and irradiation creep behavior of cladding tubes using the commercial finite element code ABAQUS and its user subroutine CREEP. The results demonstrate that creep deformation mode and magnitude are highly sensitive to geometric and mechanical factors. Specifically, longer axial lengths correlate positively with greater creep deformation, while increased wall thickness reduces it. Cladding tubes with length-to-diameter ratios exceeding 21 can be treated as infinitely long structures. Furthermore, relaxed boundary conditions have an effect equivalent to increasing the tube’s effective length, thereby amplifying creep deformation. These insights are important for evaluating cladding performance and structural safety under long-term creep deformation.