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The Reactions of Zinc Vapor With Zircaloy-4 and Pure Zirconium

Published

Author(s)

Maureen E. Williams

Abstract

The need for the Nuclear Regulatory Commission to extend the existing licenses on temporary dry storage containers of spent radioactive fuel, coated with zinc paint to prevent corrosion, from 20 years to 100 years initiated this study. The investigation of the reaction of zinc vapor on unirradiated samples of Zircaloy-4 and nuclear grade zirconium at various temperatures between 650 C and 800 C is presented.Through various analytical techniques: optical metallography, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction, the reaction of zinc vapor with Zircaloy-4 and nuclear grade zirconium was investigated. The temperatures for the diffusion experiments were based on the Zn-Zr binary phase diagram. Temperatures below 750 C were chosen to remain in the hexagonal close-packed (hcp) zirconium phase, yet high enough to insure that a reaction would occur in a reasonably short period of time. Extrapolation to 350 C would then be used to estimate the effect during dry storage. However, experiments at 725 C indicated the presence of zirconium, so additional experiments with nuclear grade zirconium at temperatures above 725 C were performed to confirm the eutectoid reaction temperature in the binary phase diagram and to investigate the solubility of zinc in zirconium.
Citation
NIST Interagency/Internal Report (NISTIR) - 6447
Report Number
6447

Keywords

Compositional, eutectoid temperature, intermetallic phase, line scan, phase diagram, scanning electron microscopy, zinc vapor, Zircaloy-4, zirconium

Citation

Williams, M. (2000), The Reactions of Zinc Vapor With Zircaloy-4 and Pure Zirconium, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 21, 2024)
Created January 1, 2000, Updated October 16, 2008