Refinement of transient analysis for Zircaloy-4 fuel sheath oxidation in air
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Date
2025-03
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University of New Brunswick
Abstract
In the absence of adequate cooling, CANDU TM 37-element Zircaloy-4 fuel sheath oxide growth predictions are simulated using an oxidation kinetic model derived from elevated isothermal experiments. However, due to the CANDU TM on-line fueling process, discharged fuel bundles undergo non-isothermal conditions initiating from decay heat flux if the transfer elevator / ladle fails. It was hypothesized that oxidation kinetics will not follow the traditional kinetics model. Experiments to test this hypothesis and develop a new oxidation kinetics model were proposed and conducted, which approximated fuel state under these conditions. The research provides a basis for (a) demonstrating the oxidation kinetics of CANDU TM fuel bundles stuck on the discharge ladle differs significantly from the currently accepted kinetics model, and (b) that resistance of a Zircaloy-4 fuel sheath can be correlated to overall oxide growth thickness on the fuel sheath.