Verifica e validazione sull’accoppiamento del codice di sistema Relap5 e il codice di fluidodinamica computazionale Fluent applicato su sistemi a piscina

This report, carried out at the DICI (Dipartimento di Ingegneria Civile e Industriale) of the University of Pisa, illustrates the activities performed in the framework of the AdP2015 and dealing with the application of an in-house developed coupling methodology between a modified version of RELAP5/Mod3.3 and Fluent commercial CFD code, to a pool system, the CIRCE (CIRCulation Experiment) experimental facility. This document initially call up the coupling methodology used, which was developed and improved in the past years. The main applications of the coupling tool to the CIRCE pool system are the main topic of this report. A simplified model with a 2D CFD domain was employed for the simulation of a long transient, representing a PLOHS+LOFA scenario, and the main results are compared with experimental data. A 3D CFD model of the pool was also developed and used to perform shorter transients, both isothermal and non-isothermal tests. Numerical results are compared with the ones from the simulations with the 2D CFD domain and from experiments. The coupled calculations showed interesting results, with some discrepancy with respect to the experiments, due to some simplifications in the modelling. This outcome gives an input for the improvement of the next simulations. In regards to this, the computational domain of the new test section CIRCE-HERO is under development and is presented in the last part of this document.