In this report the thermal fluid-dynamics results of the DHR (Decay Heat Removal) pre-test analysis of the test foreseen at ENEA by the ICE (Integral Circulation Eutectic) test section of CIRCE (CIRCulation Eutectic) facility are presented. The aim of this work is the study of the PLOHS (Protective Loss Of Heat Source) + LOF (Loss Of Flow) accident that in a LFR (Lead Fast Reactor) consists in the loss of all primary pumps and secondary circuits, with consequent reactor scram and decay heat removed in natural circulation by emergency systems (DHR-HXs). In order to better represent the boundary conditions a one way coupled model between the RELAP5 system code and the CFD Fluent code was developed. In particular, the boundary conditions implemented in the Fluent code as the HX (Heat eXchanger) removed power and the LBE (Lead-Bismuth Eutectic) flow rate at the entrance of the HS (Heater System) were set-up by previous RELAP5 stand alone simulations. The CFD (Computational Fluid Dynamic) analysis was performed adopting an axial-symmetric domain and assuming adiabatic the external walls. The natural circulation in the HLM (Heavy Liquid Metal) pool and the cooling capability of air circulating in the secondary side of the DHR were also investigated in transient conditions. Twenty hours of transient analysis were performed and at the end of that time the system had not yet reached complete steady state conditions. At t = 20 h, the temperature results show a stratified temperature field in the pool region, reaching a distribution in which the upper region is characterized by a temperature of about 316°C and a lower region in which the LB) reaches an approximately uniform value of about 283°C. The LBE mass flow rate in the DHR annular region reaches a value of about 7.5 kg/s (i.e. about 94% of the total LBE mass flow rate entering at the inlet section); under these conditions the DHR system is able to remove about 39 kW of heat power from the vessel, which represents 5% of the nominal power generated before the accident.
|Titolo:||Numerical analysis of the thermal-hydraulic behaviour of the ICE test section by the coupling of a system code and a CFD code|
|Data di pubblicazione:||18-set-2012|
|Appare nelle tipologie:||5.2 Documento in Garanzia della Qualità|