Patent Number: 059498390
Section: claims

1. A fuel assembly for a boiling water reactor, wherein the fuel assembly during operation is arranged vertically in the core of the reactor and the fuel assembly comprises: a plurality of vertical fuel rods arranged in at least one fuel bundle, wherein each of the fuel rods comprises a stack of fuel pellets surrounded by a cladding tube,  a bottom tie plate which retains and supports the lower part of the fuel bundle and is arranged at the bottom of the fuel assembly,  a number of spacers which retain and position the fuel rods in spaced relationship to each other and are arranged axially separated along the fuel rods,  a vertical water channel through which water flows upwardly through the fuel assembly, and  a fuel channel which surrounds the fuel bundle,  a top spacer which retains and supports the upper part of the fuel bundle and is arranged above and spaced apart from the stacks of fuel pellets, wherein 2. A fuel assembly according to claim 1, wherein the plenum tubes run through the top spacer and extend somewhat above the top spacer. 3. A fuel assembly according to claim 2, wherein the plenum tubes extend at least 5 cm above the top spacer. 4. A fuel assembly according to claim 1, wherein the upper part comprises a top piece provided with a handle, and the water channel terminates below and at a distance from the top piece. 5. A fuel assembly according to claim 4, wherein the water channel terminates above the top spacer. 6. A fuel assembly according to claim 4, wherein between the water channel and the top piece, an interconnecting member is arranged. 7. A fuel assembly according to claim 1, wherein the water channel is provided with inflow openings in its upper part. 8. A fuel assembly according to claim 1, wherein the water channel has a cruciform cross section. 9. A fuel assembly according to claim 1, wherein in the upper part of the plenum tube, a top plug is arranged which comprises a cylindrical pin having a diameter which is smaller than the diameter of the plenum tube.