Study of MHD Corrosion and Transport of Corrosion Products of Ferritic/Martensitic Steels in the Flowing PbLi and its Application to Fusion Blanket

Two important components of a liquid breeder blanket of a fusion power reactor are the liquid breeder/coolant and the steel structure that the liquid is enclosed in. One candidate combination for such components is Lead-Lithium (PbLi) eutectic alloy and advanced Reduced Activation Ferritic/Martensitic (RAFM) steel. The research performed here is aimed at: (1) better understanding of corrosion processes in the system including RAFM steel and flowing PbLi in the presence of a strong magnetic field and (2) prediction of corrosion losses in conditions of a Dual Coolant Lead Lithium (DCLL) blanket, which is at present the key liquid metal blanket concept in the US. To do this, numerical and analytical tools have been developed and then applied to the analysis of corrosion processes.;First, efforts were taken to develop a computational suite called TRANSMAG (Transport phenomena in Magnetohydrodynamic Flows) as an analysis tool for corrosion processes in the PbLi/RAFM system, including transport of corrosion products in MHD laminar and turbulent flows. The computational approach in TRANSMAG is based on simultaneous solution of flow, energy and mass transfer equations with or without a magnetic field, assuming mass transfer controlled corrosion and uniform dissolution of iron in the flowing PbLi. Then, the new computational tool was used to solve an inverse mass transfer problem where the saturation concentration of iron in PbLi was reconstructed from the experimental data resulting in the following correlation: CS = e 13.604--12975/T, where T is the temperature of PbLi in K and CS is in wppm. The new correlation for saturation concentration was then used in the analysis of corrosion processes in laminar flows in a rectangular duct in the presence of a strong transverse magnetic field. As shown in this study, the mass loss increases with the magnetic field such that the corrosion rate in the presence of a magnetic field can be a few times higher compared to purely hydrodynamic flows. In addition, the corrosion behavior was found to be different between the side wall of the duct (parallel to the magnetic field) and the Hartmann wall (perpendicular to the magnetic field) due to formation of high-velocity jets at the side walls.;Further analysis was performed for corrosion in the Hartmann flow, which is the MHD analog of the hydrodynamic Poiseuille flow. The main goal of the analysis is to elucidate the effect of a magnetic field on the corrosion mass loss in the case when the applied magnetic field is perpendicular to the flow-confining wall. It was found that the corrosion rate is strongly dependent of the ratio between the thickness of the concentration boundary layer and that of the magnetohydrodynamic Hartmann boundary layer.;Analysis of the effect of a magnetic field on corrosion of RAFM steel in a turbulent PbLi flow is performed using numerical simulations. As demonstrated, for all three magnetic field orientations, decrease of the corrosion rate occurs as the magnetic field increases. However, a wall-normal magnetic field has a stronger effect on the reduction of the corrosion rate compared to the other two magnetic field orientations due to more intensive turbulence suppression. For the case of a wall-normal magnetic field, a correlation for the turbulent dimensionless mass transfer coefficient (Sherwood number, Sh) has been constructed based on the numerical data, which shows the effect of the flow velocity via the Reynolds number (Re) and that of the applied magnetic field via the Hartmann number (Ha): Sh = Sh0 -- 0.792x( Ha1.289), where Sherwood number in a purely hydrodynamic flow Sh0 is a function of Re..;The developed analytical and computational tools have been used in the calculations of the corrosion mass loss in the poloidal ducts of the DCLL blanket under conditions of the so-called US DEMO reactor. The analysis includes parametric studies, using the electrical conductivity of the insulating flow channel insert (FCI) and the PbLi temperature as parameters. Also, more detailed computations have been performed using computed temperature distributions from the 3D MHD/thermofluid analysis. (Abstract shortened by UMI.).