Modelling of Oxide Layers on Zircalloy Fuel Pins under Subcooled Boiling Conditions

  • Abdulla J. Al Hammadi

    Student thesis: Master's Thesis

    Abstract

    The current study presents a numerical investigation, using a commercial code Star-CCM+, to study the effects of nanoporous oxide-layer on the heat transfer rates at pressurized water reactor (PWR) operating conditions. Beforehand, a code ability to predict two-phase flows at subcooled regime is assessed. The comparison of the current CFD predictions with existing experimental data revealed that the code is capable of predicting such flows with a reasonably good accuracy. In the second part a single-phase conjugate heat transfer simulation was carried out to study the effects of the nano-pores on the flow. The computational domain generated for this part of the study included both; the fluid domain, with a hydraulic diameter of the same order as can be found in the APR1400 fuel assemblies, and the nano-porous oxide-layer. The obtained CFD predictions revealed that the existing nanopores in the oxide layer induce perturbations in the flow similar to wall roughness effects. Hence, these numerical results were used to estimate an equivalent wall roughness which was then applied to the two-phase flow simulation. As a result, it has been observed that the presence of this oxide layer on the wall has the tendency of causing a higher evaporation rate in comparison to the case with smooth walls. The finding from the present study are aimed to contribute to a better understanding of this novel proposal benefits and improvements to the current PWRs in operation.
    Date of AwardJun 2017
    Original languageAmerican English
    SupervisorYacine Addad (Supervisor)

    Keywords

    • Zircalloy
    • Oxide layer; CHF; Subcooled boiling; Nuclear safety.

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