SYMPOSIA PAPER Published: 01 January 1989

Internal Hydriding in Irradiated Defected Zircaloy Fuel Rods


Internal hydriding of Zircaloy cladding is a persistent cause of cladding failures. It occurs in the fuel rods of water-cooled nuclear power reactors that have a small cladding defect. This report summarizes the experimental findings, causes, and mechanisms of internal hydriding in defected Zircaloy-clad fuel rods. Irradiation test data on the different types of defected fuel rods, intentionally fabricated defected and in-pile operationally defected rods, are compared. Significant factors affecting internal hydriding in defected Zircaloy-clad fuel rods (defect hole size, internal and external sources of hydrogen, Zircaloy cladding surface properties, nickel alloy contamination of Zircaloy, the effect of heat flux, and fluence) are discussed. Pertinent in-pile and out-of-pile test results from Bettis and other laboratories are used as a data base in constructing a qualitative model that explains hydrogen generation and distribution in Zircaloy cladding of defected water-cooled reactor fuel rods.

Author Information

Clayton, JC
Westinghouse Electric Corporation, Bettis Atomic Power Laboratory, West Mifflin, PA
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Developed by Committee: B10
Pages: 266–288
DOI: 10.1520/STP18870S
ISBN-EB: 978-0-8031-5084-3
ISBN-13: 978-0-8031-1199-8