D. Araneo

Integrated Software Environment for Pressurized Thermal Shock Analysis

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 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 Relap5-3D and Cathare2), during a selected transient scenario. The results so obtained are then processed to provide boundary conditions for the next step, that is, a CFD calculation. Once the system pressure and the RPV wall temperature are known, the stresses inside the RPV wall can be calculated by mean a Finite Element (FE) 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.

Use of the Natural Circulation Flow Map for Natural Circulation Systems Evaluation

The aim of this paper is to collect and resume the work done to build and develop, at the University of Pisa, an engineering tool related to the natural circulation. After a brief description of the different loop flow regimes in single phase and two phase, the derivation of a suitable tool to judge the NC performance in a generic system is presented. Finally, an extensive comparison among the NC performance of various nuclear power plants having different design is done to show a practical application of the NC flow map.

Passive Safety Systems in Advanced PWRs

Passive safety systems have been widely applied to advanced water-cooled reactors (WCRs), to enhance the safety of nuclear power plants. For the near term and medium term, the Chinese government decided for advanced pressurized water reactors with an extensive usage of passive safety systems. The International Workshop on Passive Safety Systems of Advanced PWR (IPASS’08) was held in Shanghai on April 28–30, 2008, coorganized by the Shanghai Jiao Tong University and the Pisa University. The main purposes of the Workshop IPASS’08 are (a) to provide a platform to the international nuclear community for exchanging research results and design experience on passive safety systems applied to advancedWCR and (b) to enhance the contact and collaboration between the Chinese research institutions and international partners. More than 100 scientists and nuclear engineers from eight countries, that is, Canada, China, France, Germany, Italy, Korea, Pakistan, and USA, were participating in this workshop. More than 60 technical papers were presented covering the following topics: