3d transient thermoelastic analysis of VVER-1200 nuclear reactor vessel during a loss – of – coolant accident (LOCA) scenario

In order to evaluate the structural integrity of a reactor pressure vessel (RPV), a comprehensive mechanical analysis is necessary to be performed for the transients during several operating conditions. For RPVs, because there is a sudden change in the temperature gradient across the vessel wall, it adds to the complexities while calculating the stress field there. Reactor vessels are required to be supplemented with a comprehensive thermal stress analysis. This thesis discusses the comprehensive thermoelastic stress analysis performed for RPV of a VVER-1200 by means of a numerical model. The results were utilized for structural integrity evaluation of reactor vessels. Three dimensional comprehensive simulations of fluid flow in currently operating nuclear reactors are an integral part of modern scientific research throughout the world. The highly dramatic improvements in computer-based programming capabilities recently made the detailed three-dimensional simulations of huge structures feasible and made the complex turbulence models in CFD codes relatively simple. The PWR with multiple loops might possess asymmetric operating conditions with reactor coolant pumps (RCPs) out of running in one or more loops. In this thesis, a CFD numerical analysis of the 4-loop VVER-1200 RPV is presented. Both symmetric (full-loop) and asymmetric (three-loop) inlet conditions, velocity, pressure and temperature distributions are obtained. The results match with the experimental reference values of the VVER-1200. This thesis also represents the loss-of-coolant accident (LOCA) simulation of the RPV using CFD code FLUENT 17.2 and FAVOR analysis for reflooding phase after LOCA occurred.