Aqueous Corrosion of Thorium Alloys and Zircaloy-clad Thorium Alloys
- Nuclear Metals, Inc., Concord, MA (United States)
An investigation was made of the ability of thorium alloys extrusion-clad with Zircaloy-2 to survive catastrophic rupture when the core alloy was exposed to high temperature water through a small artificial defect in the cladding. At the same time the aqueous corrosion resistance of various thorium alloys was determined at a series of temperatures, and their activation energies were obtained. Thorium-zirconium alloys containing 5-10 w/o Zr showed the lowest corrosion rate, 25 mg/cm2/hr, as compared to 150 mg/cm2/hr for unalloyed thorium in 500°F water. Defected specimens of Zircaloy-2 clad unalloyed thorium failed catastrophically after a few hours exposure to 500°F water, whereas a thorium core alloy containing 8.87o Zr showed only slight cracking of the clad near the defect after 132 hours exposure. The attack of the core alloy through the defect in the clad appeared to progress, in part, preferentially along the clad-core interface. Heat treatment of the clad alloys to form a diffusion layer between the clad and core was not successful in preventing the attack along the interface. All additions of 10% of uranium to Th - 2% Zr confined the attack to the area just beneath the defect in the clad but resulted in only a slight increase in survival time over the binary Th - 270 Zr alloy.
- Research Organization:
- Nuclear Metals, Inc., Concord, MA (United States)
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- NSA Number:
- NSA-14-015036
- OSTI ID:
- 4157985
- Report Number(s):
- NMI--1226
- Country of Publication:
- United States
- Language:
- English
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