Hydride Induced Embrittlement on Zircaloy-4 Doug Ogletree Glen Rose ISD Dr. Lin Shao (Texas A&M University) Dr. Wayne Kinnison (Texas A&M University--Kingsville)

Radiation and Materials Science Group This lab group works with particle accelerators. Accelerators are used to simulate the reactor environment, speed up materials’ development and obtain fundamental understanding of those materials. The team members are:

Ion Beam Laboratory at TAMU P.I.: Lin Shao Visiting Faculty: Wayne Kinnison (TAMUK), Zhongyu Li (HEU) Lab Manager: Mark Hollander Graduate Students: Michael Martin, Assel Aitkaliyeva (INL), Di Chen, Michael Myers(LLNL), George Wei, Tianyi Chen, Robert Balerio, Jing Wang, Michael General, Josey Wallace Undergraduate Students: Richard Vega, Travis Smith, Lloyd Price, Lance Hill, Leanne Kristek, McIan Amos, Silas Marrs

Overview My research project involves the cladding material that covers fuel rods in a nuclear reactor. The material of interest in this project is Zircaloy-4. The long term water-cooling of spent fuel rods, which are clad with zirconium alloys and come from nuclear reactors, elevates the requirement for their resistance to oxidation-related nodular corrosion. Furthermore, oxidative reaction of zirconium with water releases hydrogen gas, which partly diffuses into the alloy and forms zirconium hydrides.

Overview The hydrides are less dense and are weaker mechanically than the alloy; their formation results in blistering and cracking of the cladding – a phenomenon known as hydrogen embrittlement.

My Assignment The project is interested in studying the effect of hydrogen accumulation in Zircaloy-4 and how it causes the material to become brittle over time and try to understand how to lengthen the materials stability.

Methods I have prepared samples of Zircaloy-4 to implant hydrogen ions at various energy levels, which will result in the protons being implanted at different depths in the sample. I will characterize the samples using nano- and micro- indentation techniques. I will measure the depth of the indentations as a function of the applied force to help provide some insight into the embrittlement of the alloy.

Work Performed Soon after meeting the lab group, I got to first observe how to cut materials using a high precision saw.

Polishing My Samples Next we polished the Zirc-4 using a polishing machine.

Special Training Radiation Facility at Texas A&M University I was then trained on how to operate the accelerator.

Result of training on the 140 kV ion accelerator using 120 keV He ions.

Next Steps I will run SRIM software to get data on Zircaloy-4 to determine fluence levels. I will use nano-indentation on one of my samples to determine a baseline. I will begin the implantation of protons into the metal using different fluences. http://www.youtube.com/watch?v=qjStle6_N8I I will do the indentation measurements on the irradiated samples. Finally, I will observe the irradiated samples using SEM.

Summary It is now up to individual power plants to safely take care of the spent nuclear fuel on site. This will require storage for a long period of time. This raises safety issues for the general population. Therefore, this project will be one small piece in helping determine the continued use of Zircaloy-4 as a safe cladding material.

Acknowledgements TAMU E3 Program National Science Foundation Nuclear Power Institute Dr. Lin Shao Dr. Wayne Kinnison Michael Martin Richard Vega Michael General Josey Wallace