Coupled System and CFD Code Simulation of Thermal Stratification in SFR Protected Loss-Of-Flow Transients

摘要

For practical nuclear engineering applications, multi-scale analysis by adopting the combined use of different scale computational tools, such as system thermal-hydraulics and CFD codes, is vital when three-dimensional effects play an important role in the evolution of a given transient or accident scenario. Under US-DOE/NE's Nuclear Energy Advanced Modeling and Simulation (NEAMS) program, an SFR System Analysis Module is being developed at Argonne National Laboratory for whole-plant safety analysis. The multi-scale multi-physics modeling capability of the SFR Module is provided by integrating with other higher-fidelity simulation tools. The coupling strategy between the SFR System Module and the CFD code STAR-CCM+ is discussed first, including data exchange method, driving mechanism, time synchronization scheme, and the selection of data for exchange. Then, a protected loss-of-flow transient in a pool-type SFR was analyzed in the coupled code simulation. The importance of the multi-resolution capability was demonstrated by the multi-dimensional flow and the formation of thermal stratification layers in the core outlet plenum during the postulated transient. Although the general trends of transient evolutions are similar to the stand-alone system code simulation results, very different flow and temperature magnitudes are predicted.