Assessment of Interfacial Drag and Two Phase Pressure Drop Models of TRACE Code

Abstract

The TRAC-RELAP Advanced Computational Engine (TRACE) is currently under development by the US Nuclear Regulatory Commission (USNRC) as a next-generation thermal-hydraulics safety analysis code for reactor systems. To assess the interfacial drag and two-phase pressure drop models of the code to be used for the reactor core, an assessment program was initiated by the US NRC. This paper summarizes the TRACE (V5.0P1) code assessment for the adiabatic air-water flow in an 8x8 rod bundle geometry experiment. For this purpose, PIPE Component of the TRACE code was used. A node sensitivity study was also performed to check the effect of node size on code results. Void fraction and pressure drop were the parameters used for the comparison. The range of void fraction covered for the assessment was from 0.22 to 0.88. Code predicted pressure drop and void fraction data compared well with the experimental data with mean absolute error of 13% and 16.5% respectively.