1. Oxygen diffusion in liquid (over)stoichiometric corium.
- Author
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Delacroix, Jules, Le Tellier, Romain, and Piluso, Pascal
- Subjects
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STOICHIOMETRIC combustion , *PRESSURIZED water reactors , *NUCLEAR fuels , *NUCLEAR engineering , *APPLICATION software ,PRESSURIZED water reactor accidents - Abstract
Within the framework of pressurized water reactor severe accidents, the ICE research program is devoted to studies on a variety of fundamental mechanisms involved in Fuel-Coolant Interaction (FCI). Among them, the oxidation of liquid corium is expected to impact the premixing/fragmentation stage, thus possibly influencing the subsequent steam explosion. As a first step towards the exhaustive description of oxidation phenomena occurring in typical FCI layouts, the 1-D oxygen diffusion in liquid (over)stoichiometric spherical corium droplets is investigated in this article. A mesoscopic description is adopted, based on the evolution of oxygen concentration c O , depending on space, time, corium composition and temperature. The underlying physical model is coupled with CALPHAD-based thermodynamic calculations. An asymptotic analytical solution is first determined, assuming that the apparent diffusion coefficient D O does not depend on c O . Then, the general variational form of governing equations is derived, leading to the implementation of a related numerical approach using the finite-element method, in COMSOL® software. This numerical approach is first benchmarked with the analytical calculation, and then extrapolated to the more general case where D O varies with c O . Finally, some case studies representative of FCI issues are selected, in order to determine typical oxygen diffusion transient times within a variety of liquid corium droplets. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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