Patent Number: 046648810
Section: claims

1. A cladding tube for containing nuclear fuel material, wherein said cladding tube comprises: an outer tubular member;  an inner tubular member;  said inner tubular member located inside of said outer tubular member; the outer circumferential surface of said inner tubular member bonded to the inner circumferential surface of said outer tubular member over essentially the entire outer circumferential surface of said inner tubular member;  said outer tubular member composed of a first alloy selected from the group of zirconium alloys consisting of Zircaloy-2 and Zircaloy-4 type alloys; and Zr-Nb alloys containing about 1.0 to 3.0 w/o Nb, said inner tubular member composed of a second alloy consisting essentially of:  about 0.1 to 0.6 w/o tin;  about 0.07 to 0.24 w/o iron;  about 0.05 to 0.15 w/o chromium;  up to about 0.05 w/o nickel;  the balance of said second alloy consisting essentially of zirconium and incidental impurities;  and wherein oxygen comprises less than about 350 ppm of said alloy;  and said inner tubular member having a fully recrystallized grain structure and a wall thickness of at least about 0.003 inch.  about 0.18 to 0.24 w/o iron;  about 0.07 to 0.13 w/o chromium;  and less than about 0.007 w/o nickel.  about 0.07 to 0.20 w/o iron;  and about 0.03 to 0.05 w/o nickel.  obtaining an intermediate size composite cladding tube;  then surface beta treating an outer layer of said outer tubular member;  then cold working said intermediate size composite cladding tube in one step to substantially final size;  and then annealing said composite cladding tube at a temperature below about 600.degree. C. to produce a fine fully recrystallized grain size in said inner tubular member.  an elongate composite cladding container;  a nuclear fuel material sealed within said composite cladding container;  said elongate composite cladding container having:  said substantially cylindrically shaped pellets are stacked within said elongate composite cladding container forming a plenum space near one end of said elongate composite cladding container and wherein a spring means is located in said plenum exerting pressure on one end of said cylindrically shaped pellets;  and said plenum also containing said pressurized inert gas. 2. The composite cladding tube according to claim 1 wherein the total amount of said incidental impurities is less than about 1000 ppm. 3. The composite cladding tube according to claim 1 wherein said second alloy contains: 4. The composite cladding tube according to claim 1 wherein said second alloy contains: 5. The composite cladding tube according to claim 1 wherein said second alloy contains 0.2 to 0.6 w/o tin. 6. The composite cladding tube according to claim 3 wherein said second alloy contains 0.2 to 0.6 w/o tin. 7. The composite cladding tube according to claim 4 wherein said second alloy contains 0.2 to 0.6 w/o tin. 8. The composite cladding tube according to claim 6 wherein said first alloy is Zircaloy-4. 9. The composite cladding tube according to claim 7 wherein said first alloy is Zircaloy-2. 10. The composite cladding tube in accordance with claim 1 produced by a process comprising the steps of: 11. A water reactor nuclear fuel element comprising: 12. The fuel element according to claim 11 wherein 13. The cladding tube according to claim 1 wherein said incidental impurities are limited to the following in weight percent: 14. The cladding tube according to claim 8 wherein said incidental impurities are limited to the following in weight percent: 15. The cladding tube according to claim 9 wherein said incidental impurities are limited to the following in weight percent: 16. The water reactor nuclear fuel element according to claim 11 wherein said first alloy is Zircaloy-2. 17. The water reactor nuclear fuel element according to claim 11 wherein said first alloy is Zircaloy-4. 18. The water reactor nuclear fuel element according to claim 11 wherein said incidental impurities are limited to the following: 19. The cladding tube according to claim 1 wherein said second alloy contains 0.3 to 0.5 w/o tin. 20. The water reactor nuclear fuel element according to claim 11 wherein said second alloy contains 0.3 to 0.5 w/o tin. 21. The cladding tube according to claim 1 wherein said bond between the outer circumferential surface of said inner tubular member and the inner circumferential surface of said outer tubular member is an autogeneous bond. 22. The water reactor nuclear fuel element according to claim 11 wherein said bond between the outer circumferential surface of said inner tubular member and the inner circumferential surface of said outer tubular member is an autogeneous bond.