Patent ID: 7473329
Filing Date: 2009-01-06
Classification: C22C,C22F,G21C,Y02E,Y10T

Abstract:
1. A method of producing a cladding tube for nuclear fuel for a nuclear pressure water reactor, which method comprises the following steps: formation of a tube which at least principally consists of a cylindrical tube component of a Zr-based alloy, where the alloying element, except for Zr, which has the highest content in the alloy is Nb, wherein the Nb content in weight percent is between about 0.5 and about 2.4 and wherein no alloying element, except for Zr and Nb, in said alloy, has a content which exceeds about 0.2 weight percent, and finally annealed the cladding tube at a temperature and during a time such that said tube component is partly recrystallized but not completely recrystallized, and wherein said final anneal is carried out such that the degree of recrystallization in said tube component is higher than about 40% and lower than about 95%; wherein before said final anneal, the method comprises the following steps: forming a bar of said Zr-based alloy; heating the bar to between about 900° C. and about 1300° C. and then quenching the bar; extruding a billet from the bar after heating to between about 500° C. and about 900°C.; and cold rolling the billet into a tube in at least two steps, with heat treatments between them at between about 550° C. and about 650° C.