Modeling Corrosion in Oxygen Controlled LBE Systems with Coupling
of Chemical Kinetics and Hydrodynamics Corrosion is one of the greatest concerns
in using liquid Lead-Bismuth Eutectic (LBE) as spallation target in the Accelerator-driven
Transmutation of Waste (ATW) program. Los Alamos National Laboratory has designed
and built a Liquid Lead-Bismuth Materials Test Loop (MTL) to study materials
behavior in a flow of molten LBE. A difference of 100oC was designed between
the coldest and the hottest parts at a nominal flow rate of 8.84GPM. Liquid
LBE flow was activated by a mechanical sump pump or by natural convection.
In order to maintain a self-healing protective film on the surface of the
stainless steel pipe, a fixed concentration of oxygen has to be maintained
in the liquid metal. Therefore, it is of importance to understand what the
oxygen concentrations are in the LBE loop related to the corrosion effects
on the metal surface, the temperature profiles, the flow rates, and diffusion
rates through the metal surface. The chemical kinetics also needs to be fully
understood in the corrosion processes, coupled with the hydrodynamics. The
numerical simulation will be developed and used to analyze system corrosion
effects with different kind of oxygen concentrations, flow rates, chemical
kinetics, and geometries. The fluid flow and mass transfer near the metal
surface will be calculated based on boundary layer information. The hydrodynamics
modeling of using computational fluid dynamics will provide the necessary
levels of oxygen and corrosion products close to the boundary or surface.
The kinetics in the corrosion process between the LBE and structural materials
will be incorporated from pertinent information of hydrodynamics modeling.
The outcomes of the chemical kinetic modeling will also be fed back to the
hydrodynamics modeling. These approaches result in a predictive tool that
can be validated with corrosion test data, used to systematically design tests
and interpret the result, and provided guidance for optimization in LBE system
design.