Evaluation of Thin Plate Hydrodynamic Stability through a Combined Numerical Modeling and Experimental Effort

Abstract

An experimental and computational effort was undertaken in order to evaluate the capability of the fluid-structure interaction (FSI) simulation tools to describe the deflection of a Missouri University Research Reactor (MURR) fuel element plate redesigned for conversion to lowenriched uranium (LEU) fuel due to hydrodynamic forces. Experiments involving both flat plates and curved plates were conducted in a water flow test loop located at the University of Missouri (MU), at conditions and geometries that can be related to the MURR LEU fuel element. A wider channel gap on one side of the test plate, and a narrower on the other represent the differences that could be encountered in a MURR element due to allowed fabrication variability. The difference in the channel gaps leads to a pressure differential across the plate, leading to plate deflection. The induced plate deflection the pressure difference induces in the plate was measured at specified locations using a laser measurement technique. High fidelity 3-D simulations of the experiments were performed at MU using the computational fluid dynamics code STAR-CCM+ coupled with the structural mechanics code ABAQUS. Independent simulations of the experiments were performed at Argonne National Laboratory (ANL) using the STAR-CCM+ code and its built-in structural mechanics solver. The simulation results obtained at MU and ANL were compared with the corresponding measured plate deflections. ANL/RTR/TM-16/9Evaluation of Thin Plate Hydrodynamic Stability through a Combined Numerical Modeling and Experimental Effort ii velocity as expected and the maximum deflection for multiple experiments performed with an average flow velocity near 4.3 m/s was found to range between 5.5-7.0 mil. Due to the apparatus the plate deflection could only be measured along an azimuthally-centered line. Therefore simulations of the curved-plate experiments were performed with two models: a model that assumes that the channels are azimuthally uniform and a model that assumes azimuthally varying channels. The results obtained with the azimuthally uniform model agree well with the measured results. The azimuthally uniform model predicts a deflection of 5.6 mil for the average coolant velocity of 4.25 m/s, which under-estimated by 8% the 6.06 mil fit of the measured deflections at this fluid velocity. The results obtained with the azimuthally varying model provide a measure of the sensitivity of the deflection results to the geometry of the curved plate. The azimuthally varying model over-estimates the measured plate deflection at the leading edge by approximately 80% for an average coolant velocity of 4.0 m/s. The measured values, even at their upper 95% confidence limit of the best fit, remain bounded by the azimuthally non-uniform model.Based on the modeling of experiments there are certain points to consider relative to the expected stability of a prototypic LEU MURR fuel plate. The comparison of FSI simulation results with the measured experimental plate deflections shows that when the plate and...

Review of the Technical Basis for Properties and Fuel Performance Data Used in HEU to LEU Conversion Analysis for U-10Mo Monolithic Alloy Fuel

“…Analysis has investigated the fuel plate deformation under differential hydraulic pressures arising from flow channel differences [61]. The assumed mechanical properties AA6061 were a Young's Modulus of 68.0 GPa and a Poisson's Ratio of 0.33 [61]. This is in agreement with an evaluation of equation 3.9 at 60 °C.…”

“…As the MURR LEU fuel element design contains the thinnest and widest plates amongst the USHPRR, it serves as an important case for assessing mechanical stability under flow conditions. In work on plate deformation for the MURR fuel element, an aluminum system was studied through experiments and modeling [61]. In this study, the AA6061 modulus was used to simulate the experiments, and likewise for assessing whether a MURR LEU fuel plate would significantly deform under flow conditions as described in Section 3.1.4 (the AA6061 modulus was used for the fuel as well).…”

“…Significant mechanical deflection analysis has been done regarding MURR. Analysis has investigated the fuel plate deformation under differential hydraulic pressures arising from flow channel differences [61]. The assumed mechanical properties AA6061 were a Young's Modulus of 68.0 GPa and a Poisson's Ratio of 0.33 [61].…”

“…Given available literature data, the property values used for MURR are reasonable. In this report [61] Review of the Technical Basis for Properties and Fuel Performance Data Used in HEU to LEU Conversion Analysis for U-10Mo Monolithic Alloy Fuel 38…”

Evaluation of mechanical stability of nuclear fuel plates under axial flow conditions

“…Since Smissaert, almost no investigations have been concerned with the analysis of nuclear fuel plates with the inlet comb. After a deep search, the author can only list the technical report written by Tentner et al (2017). In that effort, a numerical analysis of a single plate with a rigid mechanical stop that prevented the deflection of the plate at its leading edge was completed using the Abaqus software.…”