Patent Number: 056278659
Section: claims

1. A nuclear fuel assembly for boiling water reactors, the assembly having a plurality of elongated parallel 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 fuel rods and having a substantially square cross-sectional area for conducting coolant/moderator about the fuel rods from the bottom of the assembly toward the top of assembly;  at least one spacer for positioning and retaining the fuel rods in a predetermined configuration;  the fuel rods being arranged with a predetermined pitch in an array of 10.times.12 where the centers of the fuel rods are located at the vertices of equilateral triangles.  a plurality of spaced apart part length fuel rods supported at their lowermost ends to the lower tie plate, and extending upwards therefrom into an upper portion of the fuel assembly,  a plurality of water rods for conducting coolant/moderator therethrough from the bottom of the assembly toward the top of the assembly;  at least one spacer for positioning and retaining fuel rods;  an outer channel surrounding the plurality of full length fuel rods and part length fuel rods and having a substantially square cross-sectional area for conducting coolant/moderator about the full length fuel rods and part length fuel rods from the bottom of the assembly toward the top of assembly;  the full length fuel rods, part length fuel rods and water rods being arranged with a predetermined pitch in an array of 10.times.12 where the centers of the full length fuel rods, the part length fuel rods, and the water rods are located at the vertices of equilateral triangles.  an outer channel surrounding the plurality of fuel rods and having a substantially square cross-sectional area for conducting coolant/moderator about the fuel rods from the bottom of the assembly toward the top of assembly;  a center water channel disposed toward the center of the cross-sectional area of the assembly and having at least one wall for conducting coolant/moderator therethrough from the bottom of the assembly toward the top of the assembly;  a plurality of water rods for conducting coolant moderator therethrough from the bottom of the assembly toward the top of the assembly;  at least one spacer for positioning and retaining the fuel rods in a predetermined configuration;  the fuel rods, water rods, and center water channel being arranged with a predetermined pitch in an array of 10.times.12 where the centers of the fuel rods are located at the vertices of equilateral triangles. 2. A nuclear fuel assembly for boiling water reactors, the assembly having: a plurality of elongated parallel full length 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; 3. A nuclear fuel assembly for boiling water reactors, the assembly having a plurality of elongated parallel 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; 4. The fuel assembly as in claim 3 wherein the center water channel comprises a tube having a diameter greater than the diameter of the fuel rod and each one of the plurality of water rods has a diameter substantially the same as the diameter of the fuel rod. 5. The assembly as in claim 4 wherein the tube which comprises the center water channel has a diameter comprising of two rod pitches and a fuel rod diameter.