Search

A submersible annular linear induction pump (ALIP) design with an outer diameter of 66.8 mm with appropriate materials is developed for circulating molten lead and alkali liquid metals of sodium and sodium-potassium-78 (NaK-78) alloy in test loops at temperatures up to 500°C. These loops investigate the compatibility of these liquid coolants with nuclear fuel and structure materials to support the development of advanced, Generation IV nuclear reactors. The present ALIP, which employs high-temperature ceramic-insulated coil wires and Hiperco-50 center core and stators, fits in Type 316 stainless steel, 2.5-in. standard schedule 5 pipe. This pipe, considered for the riser tube of the Versatile Test Reactor (VTR) in-pile test cartridge loop, has an inner diameter of 68.8 mm permitting 1.0-mm radial clearance for the present ALIP. An improved equivalent circuit model (ECM) is developed to analyze the performance of the present ALIP design. The accuracy of the model predictions is successfully validated using reported experimental measurements by other investigators for a low liquid sodium flow ALIP at 200°C and 330°C. The improved ECM calculates the performance characteristics of the present ALIP design and investigates the effects of varying the terminal voltage, current frequency, winding wire diameter, center core length, width of the liquid flow annulus, and working fluid properties and temperature on the pump operation. For circulating molten lead, the calculated peak efficiency of the present ALIP design of 6.7% occurs at a flow rate of 9.5 kg/s and pumping pressure of 263 kPa. The calculated peak efficiency for circulating liquid sodium is much higher, 26.3%, and occurs at a lower flow rate of 2.2 kg/s but a higher pumping pressure of 364 kPa. The calculated peak efficiency for circulating NaK-78 (23%) is lower than for sodium and occurs at a lower flow rate and pumping pressure of 1.9 kg/s and 310 kPa, respectively. [ABSTRACT FROM AUTHOR]

To support the development of Generation IV nuclear reactors, in-pile and out-of-pile test loops with miniature, submersible direct-current electromagnetic pumps (DC-EMPs) are used to investigate compatibility and corrosion issues of nuclear fuel and structure materials with flowing molten lead and alkali liquid metals. Owing to the absence of detailed experimental measurements and because of its simplicity and low computational cost, the equivalent circuit model (ECM) is widely used to predict the pump characteristics. The simplifying assumptions in the ECM contribute to overpredicting the pump characteristics by >10%. To gain insight into the pump operation and assess the effect of various assumptions in ECM, not possible even experimentally, this work performed three-dimensional (3-D), magnetohydrodynamic (MHD) analyses of a 66.8-mm-diameter, submersible, dual-stage DC-EMP, recently developed by the authors, for circulating molten Pb and liquid Na at up to 500°C. The solution of the coupled electromagnetism equations and the momentum and energy balance equations calculates the pump characteristics and provides 3-D images of the flow, electric current, and magnetic field strength distributions in the flow duct. The grid convergence index (GCI) criterion confirmed the adequacy of the employed numerical mesh refinement and the results conversion. Results demonstrate strong dependence of the magnetic field strength distribution in the flow duct on the value and the distribution of the electric current but negligible effects of the fluid temperature on joule heating and pump characteristics. The Lorentz force highest densities occur at the entrance of the two pumping stages, and approximately 10.0% of the total force occurs in the fringe regions upstream and downstream of pumping stages. The MHD pump characteristics are in general agreement with, but consistently lower than, the ECM predictions. For molten lead and liquid sodium, the difference between the calculated characteristics increases with increased flow rate and input current, up to 12% and 14%, respectively. [ABSTRACT FROM AUTHOR]

AbstractHeat rejection radiators of nuclear reactor power systems for space exploration and for planetary surface power are the largest component by volume and mass, depending on the radiator’s design and surface average temperature. This work developed designs for lightweight radiator modules for waste heat rejection on the lunar surface at a surface average temperature of 600 K. The modules each have a cesium (Cs)–titanium (Ti) heat pipe (HP) and highly oriented pyrolytic graphite (HOPG)/Ti heat spreading fins. The assembled panels of 10 Cs-HP modules hydraulically coupled in parallel are armored with carbon-carbon composite to protect against impacts by micrometeoroids and space debris for 10 years. The performance of the developed armored radiator panels is much superior to the current state of the art, with an areal density of 2.98 to 3.6 kg/m2, specific power of 3.36 to 3.98 kW/kg, rejected thermal power of 56.3 to 96.3 kW, and rejected power density of 7.56 kW/m2. [ABSTRACT FROM AUTHOR]

The Extended Length Test Article–Cartridge Lead is a test assembly for conducting in-pile research in the Versatile Test Reactor to support the advanced molten lead–cooled reactor under development at the Westinghouse Company. This work investigates four pumping options for circulating molten lead at 500°C and develops an integrated thermal-hydraulic model to estimate the demand curves. The four pumping options fit within cartridge riser tubes that are 57.0 and 68.8 mm in diameter. These options are (1) gas lift pumping, (2) the miniature submerged annular linear induction pump, (3) the miniature submerged direct-current electromagnetic pump, and (4) the miniature axial-centrifugal flow mechanical pump. Gas lift pumping is the simplest and is fully passive with no heat dissipation, but it generates the lowest pumping pressure and flow rate. The mechanical pump and direct-current electromagnetic pump generate the highest pumping pressures, flow rates, and average velocities of molten Pb in the test article of three-fuel rodlets in a triangular lattice. The mechanical pump designs provide the highest flow velocities in the test article and the slowest decrease in pumping pressure with increased flow rate at low thermal power dissipation. The optimized electromagnetic pump designs with no moving parts and elevated temperature ALNICO-5 permanent magnets meet or exceed the target flow velocities in the test article but at higher rate of heat dissipation than the mechanical pump designs. [ABSTRACT FROM AUTHOR]