Patent Number: 047755083
Section: claims

1. A corrosion and crack resistant water reactor fuel cladding tube comprising: an outer cylindrical layer of a first zirconium alloy selected from the group consisting of Zircaloy-2 and Zircaloy-4;  an inner cylindrical layer of a second zirconium alloy consisting essentially of:  about 0.05 to 0.2 wt.% iron,  about 0.05 to 0.4 wt.% niobium,  about 0.03 to 0.1 wt.% of an element  less than 2000 ppm total impurities;  30- 700ppm oxygen;  and zirconium forming essentially the balance;  said inner cylindrical layer metallurgically bonded to said outer layer;  and whereby said inner cylindrical layer has an aqueous corrosion resistance which is at least substantially equivalent to the corrosion resistance of said outer cylindrical layer. 2. The water reactor fuel cladding tube according to claim 1 wherein said second zirconium alloy has nickel content of 0.03-0.1 wt.% and a chromium content of less than 200 ppm. 3. The water reactor fuel cladding tube according to claim 1 wherein said second zirconium alloy has a chromium content of 0.03 to -0.1 wt.%, and a nickel content of less than 70 ppm. 4. The water reactor fuel cladding tube according to claim 1 wherein said second zironium alloy has a niobium content of 0.05 to 0.2 wt.%. 5. The water reactor fuel cladding tube according to claim 1 having a weight gain of less than 200 mg/dm.sup.2 and an essentially black, adherent oxide film on said inner and said outer layers after 24 hours exposure to a 500.degree. C. 1500 psi steam test. 6. The water reactor fuel cladding tube according to claim 1 wherein said inner cylindrical layer has a fully recrystallized microstructure.