ELECTRON AND OPTICAL MICROSCOPY ANALYSIS OF MODEL ZIRCONIUM ALLOY OXIDES
Open Access
- Author:
- Planinsek, Jacob Louis
- Area of Honors:
- Nuclear Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Arthur Thompson Motta, Thesis Supervisor
Arthur Thompson Motta, Thesis Supervisor
Igor Jovanovic, Faculty Reader
Arthur Thompson Motta, Thesis Honors Advisor - Keywords:
- zirconium oxide
zirconium corrosion - Abstract:
- Zirconium alloys are among the most important materials used in light water reactors. Zirconium alloys are used for in core structures and for nuclear fuel cladding which is the first barrier retaining radioactive fission products. The corrosion properties of zirconium alloys are the primary factor determining the life and integrity of these components. The corrosion mechanisms of pure zirconium are not well known. The oxide growth kinetics quickly transition from stable growth to breakaway growth and develops instabilities in oxide growth in the form of dendrites growing into the metal. Optical microscopy performed in this study has determined that the dendrites advance through the grain boundaries. An oxygen layer that advances ahead of the oxide is observed when the sample is well into the breakaway oxide regime. The development of the oxygen layer is key to determining the transition from stable to breakaway oxide growth. Pure zirconium can contain up to 30% oxygen as interstitials in the crystal lattice. During stable oxide growth oxygen could gather in higher concentrations at the grain boundaries that cause the oxide to advance in these boundaries and destabilize the oxide growth. The uneven stress caused by the oxide advancement could be responsible for breakaway, as evidence by the cracks observed behind the oxide in the grain boundaries.