Two-loop PWR RELAP5 to TRACE Model Conversion and Three Dimensional Vessel Model Development for Coolant Mixing Analysis

摘要

The analysis of some Design Basis Accidents requires multidimensional prediction of the thermal-hydraulic conditions in order to realistically simulate the accident. The main goal of the paper is to present the ongoing development of a model suitable for analyzing the coolant mixing phenomena in the reactor pressure vessel (RPV) of a Westinghouse (W) two-loop pressurized water reactor (PWR). The model is being developed using the best-estimate system code Trac-Relap Advanced Computational Engine (TRACE) and consists of a one dimensional model of a W two-loop PWR with a three-dimensional model of the RPV. The one dimensional TRACE input deck was converted from an existing RELAP5 input model using the Symbolic Nuclear Analysis Package (SNAP) conversion plug-in following the Jozef Stefan Institute (JSI) RELAP5 to TRACE conversion method. The three-dimensional TRACE model has been obtained by replacing the one-dimensional model of the RPV in the developed TRACE one dimensional input model with a three-dimensional model of the RPV. The three-dimensional model of the RPV has been developed using the TRACE specialized VESSEL component. Besides the presentation of the development of TRACE one dimensional and three dimensional models a preliminary steady-state calculation using the new TRACE one dimensional model is presented. For calculations, the latest TRACE V5.0 Patch 3 computer code was used. Finally, the TRACE one dimensional calculation results are compared with the RELAP5 calculation results.