Patent Number: 043483550
Section: claims

1. A fuel assembly for use in the core of a nuclear reactor, said fuel assembly comprising a plurality of separate elongated box-forming means,  a bundle of elongated fuel rods positioned in each elongated box-forming means, and  separate spaced-apart first and second end members which mount the respective opposite ends of all of said box-forming means such that they are spaced apart from one another and oriented in parallel, said first and second end members being supportable in said core. 2. A fuel assembly according to claim 1 wherein each of said box-forming means has a generally square cross section with arcuate-shaped corners. 3. A fuel assembly according to claim 2 wherein the bundle of elongated fuel rods in each elongated box-forming means has a square cross section, and wherein the fuel rods at the corners of each bundle have a smaller diameter than the other fuel rods in the bundle. 4. A fuel assembly according to claim 3 wherein each bundle of elongated fuel rods includes a hollow tube through which cooling and moderator water can be freely passed. 5. A fuel assembly according to claim 2 wherein means are provided along the length of said box-forming means to connect them together. 6. A fuel assembly according to claim 1 wherein said fuel assembly includes only four elongated box-forming means. 7. A fuel assembly according to claim 6 wherein a removable absorber rod with a burnable absorber is positioned in the spaces between the four elongated box-forming means. 8. A fuel assembly according to claim 1 wherein one of said first and second end members associated with each box-forming means includes a divider to define a plurality of parallel channels in the associated end member. 9. A fuel assembly according to claim 1 wherein each of said elongated box-forming means is disconnectable from the associated first and second end members and each of said bundles of elongated fuel rods is removable from within the associated box-forming means.