Martinez, John Calvin (2015-05). Hydrogen Interactions in Zirconium Alloys for Nuclear Applications. Master's Thesis. Thesis uri icon

abstract

  • The absorption of hydrogen in zirconium-based nuclear fuel cladding alloys is one of the most significant contributors to its degradation during long-term storage. The goal of this work was to perform a detailed study of the behavior of hydrogen in two zirconium-based alloys used in nuclear applications. Specimens were prepared through low temperature cathodic charging using an electrochemical hydrogen insertion technique. Analysis was carried out through electron microscopy, X-ray diffraction, and differential scanning calorimetry. The two alloys studied in this work were HANA-4 and Zircaloy-4. The electrochemical charging system was operated at 65 ? 5 ?C, using a 0.2 - 0.4 A/cm2 current density, in a 0.2 M sulfuric acid solution. An electrode of platinum mesh was used as the anode. Specimens were hydrogen charged to 170 wppm, Zircaloy-4, and 1600 wppm, HANA-4. The resulting hydride phases were measured through X-ray diffraction. The observed hydride phases were ?-hydride in HANA-4 and ?-hydride in Zircaloy-4. Annealing was carried out at 530 ?C, 440 ?C, and 350 ?C on sections of both alloys. The heat treatment resulted in a range of bulk hydrogen concentrations. Differential scanning calorimetry was then utilized to measure the hydride dissolution temperature in each coupon. These measurements however proved inconclusive, as the differential heat flow signals of charged and uncharged samples were difficult to distinguish.
  • The absorption of hydrogen in zirconium-based nuclear fuel cladding alloys is one of the most significant contributors to its degradation during long-term storage. The goal of this work was to perform a detailed study of the behavior of hydrogen in two zirconium-based alloys used in nuclear applications. Specimens were prepared through low temperature cathodic charging using an electrochemical hydrogen insertion technique. Analysis was carried out through electron microscopy, X-ray diffraction, and differential scanning calorimetry.

    The two alloys studied in this work were HANA-4 and Zircaloy-4. The electrochemical charging system was operated at 65 ? 5 ?C, using a 0.2 - 0.4 A/cm2 current density, in a 0.2 M sulfuric acid solution. An electrode of platinum mesh was used as the anode. Specimens were hydrogen charged to 170 wppm, Zircaloy-4, and 1600 wppm, HANA-4. The resulting hydride phases were measured through X-ray diffraction. The observed hydride phases were ?-hydride in HANA-4 and ?-hydride in Zircaloy-4.

    Annealing was carried out at 530 ?C, 440 ?C, and 350 ?C on sections of both alloys. The heat treatment resulted in a range of bulk hydrogen concentrations. Differential scanning calorimetry was then utilized to measure the hydride dissolution temperature in each coupon. These measurements however proved inconclusive, as the differential heat flow signals of charged and uncharged samples were difficult to distinguish.

publication date

  • May 2015