Reliability and efficiency of valves are necessary for precise control and sufficient heat-flow to heat application plants for the integrated energy systems of nuclear power plants (NPPs). Strategic Management Analysis Requirement and Technology (SMART) valves’ ability to control flow and assess environmental parameters stands out for these requirements. Their ability to sustain the downstream flow rate, prevent reverse flow, and maintain pressure in the heat transport loop is much more efficient with the integration of sensors and intelligent algorithms. For assessing valve performance and monitoring, mechanical design and operating conditions are two important parameters. In this study, the butterfly valves of three different sizes are simulated with water and steam using STAR-CCM+ in various flow regimes and positions to analyze performance parameters to strategize an automated control system for efficiently balancing the heat–transport network. Also, flow behavior is studied using velocity and pressure fields for valve–body geometry optimization. It can be observed, through performance parameters, that the valves are suitable for operation between 30° and 90° positions with significantly low loss coefficients and high flow coefficients, and the performance parameters follow a certain pattern in both water and steam flow in each scenario.

The Direct Reactor Auxiliary Cooling System (DRACS) is a passive heat removal system proposed for the Advanced High-Temperature Reactor (AHTR) that combines the coated particle fuel and graphite moderator with a liquid fluoride salt as the coolant. The DRACS features three coupled natural circulation/convection loops relying completely on buoyancy as the driving force. A fluidic diode has been proposed in the DRACS primary loop to maintain the passive feature. Fluidic diodes are passive flow control devices with low flow resistance in one direction and high flow resistance in the opposite direction. The fluidic diode is orientated such that during reactor normal operation the primary salt flow in the DRACS is restricted, thus preventing excessive heat loss from the reactor to the DRACS. However, when the DRACS is functioning during reactor accidents, the primary salt flow is in the forward flow direction of the diode that features low flow resistance. To investigate the reliability and thermal performance of the DRACS, a high-temperature DRACS test facility (HTDF) is being designed and constructed at The Ohio State University (OSU). In this HTDF, a conventional vortex diode has been proposed. In this paper, a detailed design process of the vortex diode for the HTDF is presented. Design parameters, such as the desired flow rates in and pressure drops across the fluidic diode, were first determined for both the forward and reverse flow directions, following which was the parametric CFD study of multiple vortex diodes with variant nozzle size, chamber size, and inlet flow rates. Flow structures inside the diode, and the effects of the nozzle size, chamber size, and Reynolds number on the Euler number were examined for both flow directions. Correlations of the forward and reverse Euler numbers and the diodicity were developed and used to develop a vortex diode design that would be applicable to the HTDF.