A numerical study for applicability of water tests to the sodium pool natural circulation analysis

Abstract

A concept of the ERVC (External Reactor Vessel Cooling) can be applied to the Sodium Fast Reactor (SFR), by using air instead of water as a coolant. The RVCS, which is a system to maintain integrity of concrete structures, can be used for reactor exterior surface cooling. The heat removal by RVCS operation affects and affected by the natural circulation inside sodium pool. Thus, understanding the natural circulation inside sodium pool is important for RVCS performance prediction. In this paper, we numerically investigated similarity laws to figure out the applicability of water tests to actual sodium condition using a commercial CFD code, STARCCM+. In this study, 4 different scales, 1/20, 1/10, 1/8 and 1/5 were investigated. In every case the volumetric heat flux of core was identical. For numerical simulation, the geometry and configuration of Prototype Gen-IV Sodium Cooled Fast Reactor (PGFSR) developed in KAERI is chosen as reference, and modeled. For comparison, each similarity laws were compared in terms of temperature field. The simulation and comparison results show that by preserving modified Bousinessq number and Peclet number when reducing the test, the temperature field of reactor can be reproduced. However, the test is too small, the flow resistance due to internal structure acts dominantly, disturbing the flow. Therefore, for better result, such flow resistance which can be occurs at small-scaled experiment, should be taken into account.