Patent Number: 051475995
Section: claims

1. A fuel assembly for a nuclear reactor which comprises a top tie plate which has a top surface, a bottom surface and a hole which extends therethrough from said top surface to said bottom surface, a bottom tie plate, a plurality of parallel fuel rods which extend between said top tie plate and said bottom tie plate, a plurality of spacer lattices positioned along said fuel rods, a plurality of guide tubes located between said fuel rods, said guide tubes being fixed to said spacer lattices, a seat in said top tie plate around said hole, a top sleeve which defines a lower end to which an upper end of a guide tube can be joined and an upper end which abuts said seat, a first locking means inside said top sleeve, a guide sleeve which is positionable through said hole in said top tie plate and into said top sleeve, and a second locking means on the outside of said guide sleeve which is cooperable with said first locking means to connect said guide sleeve and said top sleeve together. 2. A fuel assembly according to claim 1, wherein said hole through said top tie plate has a first part which extends from said top surface towards said bottom surface and a second part which extends from said first part to said bottom surface, said second part having a larger diameter than said first part, said diameter of said second part corresponding to an outer diameter of the upper end of said top sleeve and providing said seat. 3. A fuel assembly according to claim 1, wherein said first locking means comprises an inner slot which extends around a circumference of said top sleeve. 4. A full assembly according to claim 3, wherein said second locking means comprises an external bead which extends around the periphery of said guide sleeve, said bead being positionable in said inner slot of said top sleeve, and wherein said guide sleeve includes an axial slit to enable said bead to be positioned within said inner slot. 5. A fuel assembly according to claim 1, wherein said guide sleeve includes a flange that abuts said top surface of said top tie plate. 6. A fuel assembly according to claim 1, including a locking sleeve which is positionable within said guide sleeve to interlock said guide sleeve to said top sleeve. 7. A fuel assembly according to claim 6, wherein said locking sleeve is provided with a swelling which fits the indentation formed inside the guide sleeve on the back of its external bead or below the end of the guide sleeve.