Patent Number: 047708476
Section: claims

1. A nuclear fuel assembly comprising water rods and fuel rods having substantially equivalent irradiation growth wherein: the fuel rods comprise cladding tubes of a zirconium alloy formed by a first tube fabrication schedule wherein the final dimensions are achieved by cold-work reduction followed by heat treating the tube for about 1 to about 15 hours at about 1000.degree. F. to about 1300.degree. F.; and  the water rods comprise cladding tubes of a zirconium alloy substantially the same as in the fuel rod cladding tubes and formed by a second tube fabrication schedule wherein the final dimensions are achieved by cold-work reduction followed by heat treating the tube for about 1 to about 4 hours at about 825.degree. F. to about 950.degree. F.  the fuel rods comprise cladding tubes of a zirconium alloy formed by a first fabrication schedule wherein the final dimensions are achieved by about a 76% cold-work reduction in the thickness of the cladding wall followed by heat treating the tube for about 2.5 hours at about 1070.degree. F.; and  the water rods comprise cladding tubes of a zirconium alloy substantially the same as in the fuel rod cladding tubes formed by a second fabrication schedule wherein the final dimensions are achieved by about a 20% cold-work reduction in the thickness of the cladding tube wall followed by heat treating the tube for about 4 hours at about 950.degree. F. 2. A nuclear fuel assembly as recited in claim 1 wherein the fuel rod cladding tube is heat treated for about 1 to about 4 hours at about 1000.degree. F. to about 1300.degree. F. 3. A nuclear fuel assembly as recited in claim 1 wherein the select cold-work reduction in the second tube fabrication schedule comprises about a 20 percent reduction in the thickness of the tube wall. 4. A nuclear fuel assembly comprising water rods and fuel rods having substantialy equivalent irradiation growth wherein: