High temperature steam oxidation of titanium-coated Zircaloy-2 and Titanium-Zirconium Alloys

Baczynski, Jordan

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Description

Title

High temperature steam oxidation of titanium-coated Zircaloy-2 and Titanium-Zirconium Alloys

Author(s)

Baczynski, Jordan

Issue Date

2014-09-16

Director of Research (if dissertation) or Advisor (if thesis)

Stubbins, James F.

Department of Study

Nuclear, Plasma, & Rad Engr

Discipline

Nuclear, Plasma, Radiolgc Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Nuclear
• High Temperature Steam Oxidation
• Zirconium-Titanium (Zr-Ti)
• Ti-Coated Zircaloy-2

Abstract

In March 2011, the Fukushima Daiichi Nuclear Disaster changed the course of nuclear power production worldwide. Though most people have focused on the negatives of the events, there have been major advantageous outcomes. An industry, which general consensus would say is extremely safe, has become even safer based on the events that took place. Plenty of new research ideas have sprouted out of the findings and events that took place during those critical few months. One such area that is currently being studied is the reduction of hydrogen gas production due to the exothermic reaction of high temperature steam and the Zircaloy fuel cladding within the reactor during a Loss-of -Coolant Accident (LOCA). The hydrogen, which collected in the reactor vessel and containment buildings, caused devastating hydrogen gas explosions which lead to the release of radioactive isotopes into the atmosphere. Cladding material for nuclear fuel pellets must contain three major characteristics: 1) high thermal conductivity as to not reduce overall efficiency 2) relatively long period of time from the initiation of LOCA scenario and the manifestation of uncontrolled oxidation of zirconium and 3) strong resilience against nuclear bombardment (alpha, beta, gamma, fission products, etc.). The research project was centered on selecting a potential additive not previously looked into for solving the problem of high temperature oxidation of zirconium. After analyzing a variety of potential elements, Titanium was selected and tested in a variety of different ways to see the metal’s resilience under high temperature steam conditions. Along with Zirconium-Titanium (Zr-Ti) Alloy, several Zircaloy-2 Alloys were coated with Titanium layers of various thickness in the hopes of determining a positive correlation between thickness size and reduction of hydrogen production. After obtaining a 95%Zi-5%Ti Alloy and depositing titanium layers of different thicknesses onto Zircaloy-2 using magnetron sputtering, the specimens were oxidized using a STA 449 F1 Jupiter. These tests specimens were subjected to 700°C steam for a 10 hour timeframe. In a surprising twist, the Zr-Ti Foil performed surprisingly poor compared to both the coated and un-coated Zircaloy-2 samples. It is hypothesized that the reason for this was due to an uncontrollable expansion from a phase change during oxidation. For the Ti-coated Zircaloy-2 sample, the titanium began to have an effect on the overall oxidation with a thickness beginning at 64 nanometers. The results of these experiments validate the initial hypothesis that titanium, along with additional research and isotopic refinement, has the potential to be a viable coating for both current and future reactor fuel cladding designs.

Graduation Semester

2014-08

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Copyright 2014 Jordan Baczynski

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