Numerical investigation on ballooning and rupture of a Zircaloy tube subjected to high internal pressure and film boiling conditions

• Published in: Nuclear engineering and technology Vol. 55; no. 7; pp. 2454 - 2465
• Main Authors: Nguyen, Van Toan, Kim, Hyochan, Kim, Byoung Jae
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2023; Elsevier; 한국원자력학회
• Subjects: Film boiling; Fluid–thermal–structure interaction; Tube ballooning; Tube rupture; 원자력공학; Tube ballooning; Film boiling; Fluid–thermal–structure interaction; Tube rupture
• ISSN: 1738-5733; 2234-358X
• DOI: 10.1016/j.net.2023.04.002

Film boiling may lead to burnout of the heating element. Even though burnout does not occur, the heating element is subject to deformation because it is not sufficiently strong to withstand external loads. In particular, the ballooning and rupture of a tube under film boiling are important phenomena in the field of nuclear reactor safety. If the tube-type cladding of nuclear fuel ruptures owing to high internal pressure and thermal load, radioactive materials inside the cladding are released to the coolant. Therefore, predicting the ballooning and rupture is important. This study presents numerical simulations to predict the ballooning behavior and rupture time of a horizontal tube at high internal pressure under saturated film boiling. To do so, a multi-step coupled simulation of conjugated film boiling heat transfer and ballooning using creep model is adopted. The numerical methods and models are validated against experimental values. Two different nonuniform heat flux distributions and four different internal pressures are considered. The three-step simulation is enough to obtain a convergent result. However, the single-step simulation also successfully predicts the rupture time. This is because the film boiling heat transfer characteristics are slightly affected by the tube geometry related to creep ballooning.