Modeling of Dracs Test Facility and Advanced High Temperature Reactor (AHTR) Using RELAP5/SCDAPSIM/MOD 4.0

Abstract

The Advanced High Temperature Reactor (AHTR) is an advanced reactor that utilizes molten fluoridesalt as the primary coolant with enhanced safety features and higher efficiency of electricity generation. For molten-salt-cooled reactor licensing, it is critical to carry out code validation and verification (V&V). RELAP5/SCDAPSIM/MOD 4.0 includes advanced numerical techniques and options, integrated uncertainty analysis, and potential use of alternative coolants. The thermodynamic and transport properties of three molten fluoride salts, namely FLiBe, FLiNaK, and KF-ZrF4, have been implemented into RELAP5/SCDAPSIM/MOD 4.0. The code is utilized to model the thermal performance of a scaled-down Direct Reactor Auxiliary Cooling System (DRACS) test facility using implemented molten salt properties. To investigate the safety feature of DRACS, a Loss of Forced Circulation (LOFC) scenario in AHTR is simulated using RELAP5/SCDAPSIM/MOD 4.0. The results show the decay heat is sufficiently removed to the ambient air, entirely relying on natural circulation/convection.