Cladding tube of a zirconium alloy especially for a nuclear reactor fuel rod and method for fabricating the cladding tube
AssigneesKraftwerk Union Aktiengesellschaft, NRG Nuklearrohtgesellschaft mbH
InventorsSiegfried Reschke, Eckard Steinberg
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Abstract
Cladding tube of a zirconium alloy especially for a nuclear reactor fuel rod, characterized by the feature that the geometric mean of the grain diameters in the zirconium alloy is smaller than or equal to 3 .mu.m.
Claims6
A nuclear reactor fuel rod having a cladding tube formed solely of a zirconium alloy, characterized by the feature that the geometric mean of the grain diameters in the zirconium alloy is smaller than or equal to 3 .mu.m to minimize deep cracks in the cladding tube caused by chemically active nuclear fission products liberated from nuclear fuel in the cladding tube.
Method of manufacturing a finished cladding tube formed solely of a zirconium from a starting tube of a zirconium alloy in which the geometric mean of the grain diameters in the zirconium alloy is greater than 3 .mu.m, for a nuclear reactor fuel rod, in which finished cladding tube the geometric mean of the grain diameters in the zirconium alloy is smaller than or equal to 3 .mu.m, which comprises, pilger-rolling a starting tube consisting essentially of a zirconium alloy in a plurality of pilger-rolling steps sufficient to obtain a cross section change of the tube wall of 90% or more and to reduce the geometric mean of the grain diameters in the zirconium alloy to smaller than or equal to 3 .mu.m and produce a finished cladding tube without recrystallization anneal and free of cracks.
Dependencies are inferred from the claim text.