Patent Number: 061920983
Section: claims

1. A corrosion resistant nuclear fuel element for a boiling water nuclear reactor comprising: an elongated hollow metallic tubular cladding for containing a nuclear fuel, the tubular cladding comprising an outer tubular layer having an outer wall and an inner wall and an inner portion disposed between the outer wall and the inner wall, the outer tubular layer formed from metal selected from the group consisting of zirconium and a zirconium alloy having integrally incorporated a predetermined concentration of oxygen, said predetermined concentration of oxygen being a decreasing oxygen concentration gradient from the outer wall extending into the inner portion, so that when subject to corrosion zirconium hydrides preferentially precipitate in the inner portion and are inhibited from forming on the outer wall;  a body of nuclear fuel material disposed in the tubular cladding; and  sealing means at both ends of the tubular cladding.  an elongated hollow metallic tubular cladding for containing a nuclear fuel, the tubular cladding comprising:  an outer tubular layer having an outer wall and an inner wall and an inner portion disposed between the outer wall and the inner wall, the outer tubular layer formed from a metal selected from the group consisting of zirconium and a zirconium alloy, the outer tubular layer having integrally incorporated a first predetermined concentration of oxygen;  an inner tubular layer bonded to the inner wall of the outer tubular layer and formed from a metal comprising zirconium, the inner tubular layer having integrally incorporated a second predetermined concentration of oxygen, said second predetermined concentration of oxygen being less than said first predetermined concentration of oxygen so that when subject to corrosion, zirconium hydrides preferentially precipitate in the inner tubular layer and are inhibited from forming in the outer layer;  a body of nuclear fuel material disposed in the tubular cladding;  sealing means at both ends of the tubular cladding for hermetically sealing the metallic tubular cladding;  wherein the tubular cladding further includes an innermost layer bonded to an inner wall of the inner layer; the innermost layer formed from a metal selected from the group consisting of zirconium and a zirconium alloy and having integrally incorporated a third predetermined concentration of oxygen; and  wherein said first predetermined concentration of oxygen is at least about 1600 ppm and said third predetermined concentration of oxygen is at least about 1600 ppm.  an elongated hollow metallic tubular cladding for containing a nuclear fuel, the tubular cladding comprising an outer tubular layer having an outer wall and an inner wall and an inner portion disposed between the outer wall and the inner wall, the outer tubular layer formed from metal selected from the group of zirconium and a zirconium alloy having integrally incorporated a predetermined concentration of oxygen, said predetermined concentration of oxygen being a decreasing oxygen concentration gradient from the outer wall extending into the inner portion, so that when subject to corrosion zirconium hydrides preferentially precipitate in the inner portion and are inhibited from forming on the outer wall.  an elongated hollow metallic tubular cladding for containing a nuclear fuel, the tubular cladding comprising an outer tubular layer having an outer wall and an inner wall and an inner portion disposed between the outer wall and the inner wall, the outer tubular layer formed from metal selected from the group of zirconium and a zirconium alloy having integrally incorporated a predetermined concentration of oxygen, said predetermined concentration of oxygen being a decreasing oxygen concentration gradient from the outer wall extending into the inner portion, so that when subject to corrosion zirconium hydrides preferentially precipitate in the inner portion and are inhibited from forming on the outer wall;  a body of nuclear fuel material disposed in the tubular cladding; and  sealing means at both ends of the tubular cladding. 2. The corrosion resistant nuclear fuel element as in claim 1 wherein the decreasing oxygen concentration gradient from the outer wall extending into the inner portion decreases from at least about 1600 ppm to less than about 1200 ppm. 3. The corrosion resistant nuclear fuel element as in claim 1 wherein the tubular cladding further includes an inner layer bonded to the inner wall of the outer tubular layer. 4. The corrosion resistant nuclear fuel element as in claim 3 wherein the inner layer is formed from a metal selected from the group consisting of zirconium, a zirconium alloy and stainless steel. 5. A corrosion resistant nuclear fuel element for a boiling water nuclear reactor comprising; 6. The corrosion resistant nuclear fuel element as in claim 5 wherein said second predetermined concentration of oxygen is less than about 1200 ppm. 7. A corrosion resistant cladding tube for nuclear fuel for a water boiling nuclear reactor comprising: 8. The corrosion resistant cladding tube as in claim 7 wherein the decreasing oxygen concentration gradient from the outer wall to the inner wall decreases from at least about 1600 ppm to less than about 1200 ppm. 9. The corrosion resistant cladding tube as in claim 7 wherein the tubular cladding further includes an inner layer bonded to the inner wall of the outer layer. 10. The corrosion resistant cladding tube as in claim 9 wherein the inner layer is a metal comprising zirconium. 11. A corrosion resistant nuclear fuel assembly for a boiling water reactor, the assembly having a plurality of nuclear fuel rods supported between a lower tie plate positioned toward the bottom of the assembly and an upper tie plate positioned toward the top of the assembly, an outer channel surrounding the plurality of nuclear fuel rods for conducting coolant moderator about the fuel rods from the bottom of the assembly toward the top of assembly, spacer grids for positioning and retaining the fuel rods in a spaced relationship, at least one of the plurality of nuclear fuel rods comprising a metallic tubular fuel rod cladding containing nuclear fuel pellets therein, and having end sealing means thereon to hermetically seal the nuclear fuel pellets within the metallic tubular fuel rod cladding, wherein at least one of the nuclear fuel rods is comprised of: