Nuclear Energy for New Europe 2009

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No: 219

Conference: Nuclear Energy for New Europe 2009

Title: Integrated Software Environment for Pressurized Thermal Shock analysis

Theme: Thermal Hydraulics

Author(s): Dino Araneo, Fabio Moretti, Paolo Ferrara, Andrea Rossi, Andrea Latini, Francesco D'Auria

Contact : Dino Araneo

E-mail: d.araneo@ing.unipi.it

Address: Department of Mechanical, Nuclear and Production Engineering, University of Pisa
56126 Pisa

Country: Italy

The present paper describes the main features and an application to a real Nuclear Power Plant (NPP) of 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 Reactor Pressure Vessel (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. The platform automates all these steps foreseen in the methodology once the user specifies a number of boundary conditions at the beginning of the simulation.

No:	219
Conference:	Nuclear Energy for New Europe 2009
Title:	Integrated Software Environment for Pressurized Thermal Shock analysis
Theme:	Thermal Hydraulics
Author(s):	Dino Araneo, Fabio Moretti, Paolo Ferrara, Andrea Rossi, Andrea Latini, Francesco D'Auria
Contact :	Dino Araneo
E-mail:	d.araneo@ing.unipi.it
Address:	Department of Mechanical, Nuclear and Production Engineering, University of Pisa 56126 Pisa
Country:	Italy

The present paper describes the main features and an application to a real Nuclear Power Plant (NPP) of 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 Reactor Pressure Vessel (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. The platform automates all these steps foreseen in the methodology once the user specifies a number of boundary conditions at the beginning of the simulation.