مشخصات پژوهش

This study investigates the creep and damage behaviour of a thick-walled spherical vessel subjected to severe thermal conditions in a hypothetical scenario. The vessel experiences an abrupt internal temperature change, potentially leading to catastrophic failure. In this scenario, the continuous growth of plastic deformation due to the drastic temperature increase is identified as the primary cause of vessel failure. To address this, the finite element method was employed to simulate the transient thermal response and plastic creep strain within the vessel. Uni-axial creep experiments were carried out to determine the material's creep characteristics. A damage criterion was utilized to predict the onset of catastrophic failure. An approximate experimental method was employed to confirm the predicted damage initiation in the numerical solutions. The methodology applied in this research enables accurate forecasting of the moment when damage initiation occurs. The finding emphasizes that vessels used in nuclear reactors must be designed with consideration of the probability of unexpected and severe temperature changes.