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• For the solid-phase oxygen control LBE system, numerical simulations are performed for the 1:1 scale 3D UPBEAT loop. • Simulation results are in general agreement with experimental results at about 350℃ and empirical correlations at 500℃. • The mass transfer coefficient increases with the temperature and it reaches its maximum at about 475℃. The Venturi-type solid-phase oxygen control system with a bypass mass exchanger is widely regarded as an effective approach to keep the oxygen concentration in the LBE under reasonable ranges to reduce the corrosion. In this work, numerical simulations of the particle–fluid mass transfer of the oxygen concentration in LBE are performed for the 1:1 scale 3D UPBEAT loop under various conditions. The discrete element method is applied to generate the geometry of the packing of the PbO spheres. The velocity profile and oxygen concentration governing equations are solved by using the SST turbulence model. At the same temperature, the oxygen mass transfer coefficient increases monotonically with the flow rate. At the same mass flow rate, the mass transfer coefficient increases with the temperature, reaching a maximum at about 475 °C. It provides guidance for future research in the design and optimization of oxygen control systems under high temperature in lead–bismuth nuclear reactors. [ABSTRACT FROM AUTHOR]

The corrosion behavior was investigated in a static environment of liquid Pb-Bi eutectic (LBE) saturated with 10−6 wt.% oxygen at 500°C and 600 °C. The investigation focused on 15-15Ti and 15-15Ti-Y austenitic stainless steel specimens, exposing them for up to 5000 h. Additionally, both steel types were analysed after exposure to liquid Pb 40 Bi 60 alloy with 10−6 wt.% oxygen concentration at 600 °C for 2000 h. The main objective was to investigate the structure and composition of oxide layers formed during corrosion, with specific attention to the role of yttrium (Y) in influencing corrosion behavior. The addition of Y resulted in promoting denser spinel oxide layer formation, which exhibited enhanced properties in reducing outward cation diffusion, inward oxygen diffusion, and PbBi penetration into the steels. [ABSTRACT FROM AUTHOR]

• A mass exchanger was designed to develop solid phase oxygen control technology. • The dissolution rates of PbO at various conditions were obtained. • The control of the oxygen concentration was achieved in the LBE loop. The precise control of dissolved oxygen in lead–bismuth eutectic (LBE) reactors is very important. Solid phase oxygen control is a promising solution for regulating dissolved oxygen in the LBE. In order to better develop solid phase control technology, we designed a bypass mass exchanger holding PbO pellets. The dissolved oxygen in the LBE loop was controlled by PbO mass exchanger (PbO MX) technology. PbO MX is composed of a packed bed charging bucket, PbO ceramic pellets and bypass. The oxygen concentration in LBE under different conditions was measured using electrochemical oxygen sensors. The dissolution rate of PbO at different temperatures and flow rates were obtained. The effect of LBE flow rate and temperature parameters on the oxygen supply performance was obtained from the experimental results. The high-precision control of the dissolved oxygen concentration was achieved in the LBE loop. [ABSTRACT FROM AUTHOR]

For the proper design and operation of lead oxide mass exchanger (PbO MX), the dissolution kinetics of PbO in flowing liquid Lead-bismuth eutectic (LBE) needs to be determined. A computational fluid dynamics (CFD) method of the PbO MX was established. The solid-phase oxygen control part of the MX is PbO spheres packed bed, which is regarded as a porous media in the simulation calculation. The oxygen mass transfer process between PbO spheres packed bed and liquid LBE was simulated by a porous media model with the species transport model. The relationship between the dissolution rate of MX and the flow rate, temperature and initial oxygen concentration is predicted. The dissolution rate of PbO increases exponentially with increasing temperature of LBE. Besides, the dissolution rate of oxygen is positively correlated with the LBE flow velocity. In the specific oxygen concentration range, the MX inlet oxygen concentration has little effect on the dissolution rate. The smaller the porosity of PbO spheres packed bed has, the smaller the dissolution rate of oxygen is. Furthermore, when the porosity is constant, the dissolution rate of oxygen increases with the increase of the height of the packed bed of PbO spheres. • The porous media model is used to simulate the oxygen mass transfer of lead oxide mass exchanger (PbO MX). • The dissolution rate of PbO increases exponentially with increasing temperature of LBE. • The oxygen dissolution rate is proportional to the flow rate with other conditions fixed. • The small porosity leads to the decrease of the LBE velocity, causing a lower dissolution rate. [ABSTRACT FROM AUTHOR]