Accoppiamento di codici CFD e codici di sistema

This report describes the work performed by the Gruppo di Ricerca Nucleare di San Piero a Grado (GRNSPG) of the University of Pisa (as member of CIRTEN consortium) in the frame of the “Accordo di Programma MSE-ENEA sulla Ricerca di Sistema Elettrico - Piano Annuale di Realizzazione 2012”. In particular, this report constitutes the deliverable LP2.c.1_d of the corresponding activity scheduled in “Linea Progettuale 2” of Project B.3.1. The activity deals with the development and improvement of coupling techniques between Computational Fluid Dynamics (CFD) codes and thermal-hydraulic (TH) system codes, techniques that are expected to enhance the analysts’ and designers’ capabilities to simulate and predict the behavior of nuclear reactors (including those belonging to Generation IV) during normal and abnormal operating conditions. The work described in this report is a follow-up of that previously performed in the frame of PAR 2011. That initial work consisted in a review of the existing and accessible literature and technical documentation on the same subject (so as to identify the “state-of-the-art”) and in a preliminary development work aimed at a coupling interface between the CFD code ANSYS CFX and the system code RELAP5 (including a demonstrative application). Such preliminary development work brought to the definition of a coupling strategy and of the related needs in terms of software and information technology development, to the availability of a first rough but effective coupling tool, and to the identification of technical open issues and needs for further development and improvement work (such as convergence issues, V&V aspects, practical usability of the coupling tool etc.) Those outcomes constituted the starting point for the present activity, which had the objective of improving and further developing and testing the coupling tool.