International Congress on Advacned Nuclear Power Plants in Hollywood, Florida, June 9-13, 2002 Numerical Modeling of Lead Oxidation in Controlled Lead Bismuth Eutectic Systems: Chemical Kinetics and Hydrodynamic Effects Authors: Chao Wu, Kanthi Kiran Dasika, Yitung Chen, and Samir Moujaes Department of Mechanical Engineering, University of Nevada, Las Vegas 4505 Maryland Parkway, Las Vegas NV, 89154-4027 chaow@unlv.edu , kanthid@egr.unlv.edu . uuchen@nye.nscee.edu , Samir@me.unlv.edu Abstract - Using liquid Lead-Bismuth Eutectic (LBE) as coolant in nuclear systems has been studied for more than 50 years. And LBE has many unique nuclear, thermo physical and chemical attributes which are attractive for practical application. But, 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 the Liquid Lead-Bismuth Materials Test Loop (MTL) to study the materials behavior in a flow of molten LBE. A difference of 100 0 C 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 certain 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 the system corrosion effects with different kind of oxygen concentrations, flow rates, chemical kinetics, and geometries. The hydrodynamics modeling of using computational fluid dynamics will provide the necessary the levels of oxygen and corrosion products close to the boundary or surface. This paper presents an approach towards the above explained tasks by analyzing the reactions between the Lead and oxygen at a couple of sections in the MTL. Attempt is also made to understand the surface chemistry by choosing an example model and estimating the near wall surface concentration values for propane and oxygen. I. INTRODUCTION The concept of a nuclear reactor using Lead- Bismuth Eutectic (LBE) as a coolant was considered in United States in the 1950’s and it was put into practical use by Russians in submarine reactors (1) . LBE has exceptional chemical, thermal physical, nuclear and neutronic properties well suited for nuclear coolant and spallation target applications. In particular, LBE has a low melting temperature (123.5 0 C) and very high boiling temperature (~1670 0 C), is chemically inert and does not react with air and water violently, and can yield close to 30 neutrons per 1 GeV proton. However, LBE corrosion has long been recognized as a leading obstacle to its nuclear applications and LBE has not been used in high-power spallation targets (2) . In recent years, more and more research is focused on this area. Liquid LBE alloy is known to be particularly aggressive towards iron and nickel, main components of stainless steels. The long-term reliability of piping containing LBE is determined by its resistance to being dissolved, eroded or corroded by the liquid. One technique to solve this problem is to employ active oxygen control. The resistance to corrosion is greatly enhanced if a protective layer of oxide exists on the metal surfaces in contact with liquid. LBE is relatively inert compared to the metal components in steel (3) . Once Fe and Cr based oxides are formed on the steel surface; the dissolution of metal comes to a negligible level so that the loop is able to sustain a 2-3 year period that satisfies the design. Materials Test Loop (MTL) is a facility designed to test the safe operation of a medium-size, forced circulation LBE system with representative thermal hydraulic conditions (as spallation target and/or transmutation blanket systems), to perform corrosion tests, and to develop candidate materials with oxygen