Validation of a Multiscale Model of the Second Shutdown System of an Experimental Nuclear Reactor

Abstract

A three-dimensional multiscale numerical model is presented in order to describe the fluid dynamics associated to the Second Shutdown System (SSS) of an experimental nuclear reactor. Detailed computational fluid dynamics simulations were performed in a RA-10 SSS Mockup similar to the RA-10 SSS. The main component of the SSS is the reflector tank which must be drained in a limited amount of time through a series of pipes. The modeling of the complete system is based on coupling subsystems through dynamic boundary conditions. Numerical simulations results allow to determine the location of the free-surface in the tank. For validation purpose, the location of the interface was compared with experimental data measured in a local manner. For verification, the unsteady-state macroscopic mechanical energy balance was used. A good agreement between the several interface estimators after an initial transient with wave motion is shown. The results prove that the multiscale approach is suitable to reproduce the overall behavior of the fluid dynamics of RA-10 SSS Mockup.