The present paper describes an Integrated Software Environment (in the following referred to as “platform”) developed at University of Pisa (UNIPI) to perform Pressurized Thermal Shock (PTS) analysis. The need of such tool rises from the difficulty connected to the exchange of data among proprietary and non proprietary codes used in the analysis such as Relap5, Cathare2, CFX and ANSYS Multi-physics, each code having its own specific format for data input and output. The platform is written in Java for the portability and it implements all the steps foreseen in the methodology developed at UNIPI for the deterministic analysis of PTS scenarios. The methodology starts with the thermal hydraulic analysis of the NPP with a system code (such as Relap5, Cathare2, etc.), during a selected transient scenario, in order to calculate the cooling loads induced on the internal RPV wall surface by the Emergency Core Coolant (ECC) injection. The results so obtained are then processed to provide boundary conditions for the next step, i.e. a CFD calculation of the mixing phenomena occurring at small scale on the RPV welding lines region of the down-comer. Once the system pressure and the RPV wall temperature are known, a stress analysis can be performed to evaluate both thermal and mechanical stresses by means of a Finite Element (FE) structural mechanics code. The last step of the methodology is the Fracture Mechanics (FM) analysis, using weight functions, aimed at evaluating the stress intensity factor (KI) at crack tip to be compared with the critical stress intensity factor KIc. All these steps are described, along with the implementation technique, by a sample application to a real NPP.
Development of an Integrated Software Environment for Pressurized Thermal Shock analysis
D'AURIA, FRANCESCO SAVERIO
2009-01-01
Abstract
The present paper describes an Integrated Software Environment (in the following referred to as “platform”) developed at University of Pisa (UNIPI) to perform Pressurized Thermal Shock (PTS) analysis. The need of such tool rises from the difficulty connected to the exchange of data among proprietary and non proprietary codes used in the analysis such as Relap5, Cathare2, CFX and ANSYS Multi-physics, each code having its own specific format for data input and output. The platform is written in Java for the portability and it implements all the steps foreseen in the methodology developed at UNIPI for the deterministic analysis of PTS scenarios. The methodology starts with the thermal hydraulic analysis of the NPP with a system code (such as Relap5, Cathare2, etc.), during a selected transient scenario, in order to calculate the cooling loads induced on the internal RPV wall surface by the Emergency Core Coolant (ECC) injection. The results so obtained are then processed to provide boundary conditions for the next step, i.e. a CFD calculation of the mixing phenomena occurring at small scale on the RPV welding lines region of the down-comer. Once the system pressure and the RPV wall temperature are known, a stress analysis can be performed to evaluate both thermal and mechanical stresses by means of a Finite Element (FE) structural mechanics code. The last step of the methodology is the Fracture Mechanics (FM) analysis, using weight functions, aimed at evaluating the stress intensity factor (KI) at crack tip to be compared with the critical stress intensity factor KIc. All these steps are described, along with the implementation technique, by a sample application to a real NPP.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
