Patent Number: 059404647
Section: claims

1. A tube of zirconium-base alloy for constituting all or the outside portion of cladding for a nuclear fuel rod or of a guide tube for a nuclear fuel assembly, made of a zirconium-base alloy containing, by weight, 0.8% to 1.8% niobium, 0.2% to 0.6% tin, and 0.02% to 0.4% iron, plus inevitable impurities, and having a carbon content controlled to lie in the range 30 ppm to 180 ppm, a silicon content in the range 10 ppm to 120 ppm, and an oxygen content in the range 600 ppm to 1800 ppm. 2. A tube according to claim 1, wherein the alloy is in recrystallized state. 3. A tube according to claim 1, wherein the alloy is in relaxed state. 4. A tube according to claim 1, wherein the alloy has set contents: 0.9% to 1.1% niobium, 0.25% to 0.35% tin, and 0.2% to 0.3% iron. 5. A method of manufacturing a tube according to claim 1, including the following steps of: making a bar of an alloy containing 0.8% to 1.8% niobium, 0.2% to 0.6% tin, and 0.02% to 0.4% iron;  after heating in the bar to a temperature in the range 1000.degree. C. to 1200.degree. C., quenching the bar in water;  drawing the bar into a blank after heating to a temperature in the range 600.degree. C. to 800.degree. C.;  annealing the drawn blank at a temperature in the range 590.degree. C. to 650.degree. C.; and  cold rolling the annealed blank in at least four passes into a tube, with intermediate heat treatments at temperatures in the range 560.degree. C. to 620.degree. C. 6. A method according to claim 5, wherein the rolling passes are performed on tubes having increasing recrystallization ratios. 7. A method according to claim 5, further including a recrystallizing final heat treatment step at a temperature in the range 560.degree. C. to 620.degree. C. 8. A method according to claim 5, further including a strain relieving final heat treatment step at a temperature in the range from about 470.degree. C. to 500.degree. C.