(307h) Thermal-Hydraulics, Transient Turbulence, and Two-Phase Flows in a Pressurized-Water Small Modular Nuclear Reactor

A computational model of a pressurized water-cooled small modular nuclear reactor based on the 800 MWth design by Westinghouse Nuclear was designed and analyzed for fluid flow and heat transfer phenomena. Simulations were carried out in several stages using commercial CFD package, STAR-CCM+. The complex geometry of internal structures and heat sources provided a massive, multi-scale domain through which turbulent flow and conjugate heat transfer were simulated. Data was extracted at relevant locations and compared with benchmark data from prior studies, for validation. Novel designs were introduced in this study; an integral pressurizer unit, and an annular, integral steam generator unit, both of which were conventionally placed outside the reactor pressure vessel.

The reactor pressure vessel consists of primary and secondary coolant loops. The primary coolant extracts heat from enriched UO2 fuel rods, and transports this heat via turbulent flow past internal structures to the tube-side of the integral steam generator. The secondary coolant flows in on the shell-side of the integral steam generator and extracts sufficient heat to exit as a steam-water mixture with ~60% quality, providing secondary-side electricity generation equipment with a deliverable power of 225 MW. These phenomena were simulated and analyzed, and are presented herewith.