Computational Fluid Dynamics Analysis of the Core of the MOTEL Facility

Abstract

This paper presents the computational fluid dynamics analysis of the core of the Modular Test Facility (MOTEL), an integral test facility recently commissioned in the nuclear safety research laboratory of LUT University. The MOTEL is a model of an SMR that resembles the design of the NuScale type SMR. The current implementation of MOTEL represents a prototypical integral pressurized water small modular reactor (SMR) operating with natural circulation. The facility can operate at a pressure of up to 40 bar and a temperature of 250 °C. It has a total height of 7.4 m and a diameter of 711 mm, with a maximum heating power of 1000 kW. The MOTEL core comprises 132 electrically heated heater rods, 145 dummy rods, and 16 measurement probes. The diameter of the core is relatively large. Only one-fourth of the MOTEL's core geometry was simulated for this study using the ANSYS FLUENT CFD tool. Various core power distributions were analyzed. Flow turbulence was solved by employing Shear Stress Transport (SST) k-ω turbulence models. Results show that CFD can help evaluate phenomena that are difficult to reproduce or costly to analyze experimentally at a lower cost and with reasonable accuracy, making it a key advantage in the nuclear industry.