The FEM analysis of pressure installation elements after simulated accidental overheating

摘要

The paper presents innovative analysis focused on the safety aspects of existing pressure installation operation after overheating accidents. Results presented here can be applied in decision-making process concerning further operation of existing pressure installation after cooling system failure. In this paper the results of FEM analysis performed for a straight pipe and 90? elbow, made of super duplex stainless steel, for initial microstructure (microstructure after manufacturing) and after precipitation of sigma phase (σ), were presented. Heat treatment conditions simulate accidental overheating that can occur in nuclear power plants after primary cooling circulation fails. For initial and thermally modified microstructure, a tensile test was performed experimentally and numerical description of work hardening curves was done. The paper concerns the applicability of microstructure properties after simulated overheating accidents for analysis of existing pressure installation elements. Verification of FEM results was performed on the basis of empirical equations describing circumferential stresses in straight pipe. Stress distribution and deformation in both geometries reveals areas with highest risk of damage in pressure installation. According to the results of presented calculations, after simulated accidental overheating of existing pressure installation elements, changes of acceptable internal pressure were observed.