Spacer and a Fuel Unit for a Nuclear Plant

Abstract

The invention refers to a spacer for holding a number of elongated fuel rods intended to be located in a nuclear plant, and a fuel unit with such spacers. The spacer encloses a number of cells for receiving a respective fuel rod extending in parallel to a longitudinal axis of the respective cell. Each cell is formed by a sleeve-like member having an upper edge and a lower edge. The sleeve-like member includes a number of abutment surfaces projecting inwardly towards and extending substantially in parallel with the longitudinal axis for abutment to the fuel rod the cell. The lower edge and the upper edge have, seen transversely to the longitudinal axis, a wave-like shape with wave peaks, aligned with a respective one of said abutment surfaces, and wave valleys located between two adjacent ones of said abutment surfaces.

1 - 27 . (canceled) 
   
   
       28 . A spacer for holding a number of elongated fuel rods intended to be located in a nuclear plant, comprising:
 a spacer enclosing a number of cells, each cell having a longitudinal axis and arranged to receive a fuel rod in such a way that the fuel rod extends substantially parallel with the longitudinal axis,   each cell being formed by a sleeve-like member, having an upper edge and a lower edge,   the sleeve-like member including a number of abutment surfaces, which project inwardly towards the longitudinal axis and extend substantially parallel with the longitudinal axis for abutment to the fuel rod to be received in the cell, and   the lower edge, seen transversely to the longitudinal axis, having a wave-like shape with wave peaks, which are aligned with a respective one of said abutment surfaces, and wave valleys located between two adjacent ones of said abutment surfaces; and wherein   the upper edge, seen transversely to the longitudinal axis, has a wave-like shape with wave peaks, which are aligned with a respective one of said abutment surfaces, and with wave valleys located between two adjacent ones of said abutment surfaces.   
   
   
       29 . A spacer according to  claim 28 , wherein said elongated abutment surfaces extend from the upper edge to the lower edge. 
   
   
       30 . A spacer according to  claim 28 , wherein each sleeve-like member includes at least four of said abutment surfaces. 
   
   
       31 . A spacer according to  claim 28 , wherein each of said abutment surfaces is formed by a respective ridge projecting inwardly towards the longitudinal axis. 
   
   
       32 . A spacer according to  claim 28 , wherein the sleeve-like members abut each other in the spacer along a connection area extending in parallel to the longitudinal axis between one of said wave valleys of the upper edge and one of said wave valleys of the lower edge. 
   
   
       33 . A spacer according to  claim 28 , wherein the sleeve-like members are permanently connected to each other by means of weld joints. 
   
   
       34 . A spacer according to  claim 32 , wherein said weld joint includes an edge weld at said connection area at least one of the upper edge and the lower edge. 
   
   
       35 . A spacer according to  claim 33 , wherein said weld joint includes an edge weld at said connection area at least one of the upper edge and the lower edge. 
   
   
       36 . A spacer according  claim 28 , wherein substantially each sleeve-like member is manufactured in a sheet-shaped material that is bent to the sleeve-like shape. 
   
   
       37 . A spacer according to  claim 36 , wherein the sheet-shaped material before said bending has a first connection portion in the proximity of the a first end of the sheet-shaped material and a second connection portion in the proximity of a second end of the sheet-shaped material, wherein the first end overlaps the second end of the sleeve-like member after said bending. 
   
   
       38 . A spacer according to  claim 36 , wherein the first connection portion and the second connection portion are permanently connected to each other by means of at least one weld joint. 
   
   
       39 . A spacer according to  claim 38 , wherein said weld joint includes a spot weld. 
   
   
       40 . A spacer according to  claim 28 , wherein substantially each sleeve-like member is manufactured from a tubular material which is worked to the wave-shaped shape of the upper edge and the lower edge. 
   
   
       41 . A spacer according to  claim 28 , wherein the sleeve-like member seen in the direction of the longitudinal axis has four substantially orthogonal long sides, wherein each long side includes one of said abutment surfaces. 
   
   
       42 . A spacer according to  claim 41 , wherein each long side includes one of said wave peaks of the upper edge and one of said wave peaks of the lower edge. 
   
   
       43 . A spacer according to any  claim 41 , wherein the sleeve-like member, seen in the direction of the longitudinal axis, has four substantially orthogonal short sides, wherein each short side connects two of said long sides and includes with a portion of one of said wave valleys of the upper edge and a portion of one said wave valleys of the lower edge. 
   
   
       44 . A spacer according to  claim 28 , wherein the sleeve-like member has a thickness of the material, which is less than 0.24 mm. 
   
   
       45 . A spacer according to  claim 28 , wherein the sleeve-like member has a thickness of the material, which is less than or equal to 0.20 mm. 
   
   
       46 . A spacer according to  claim 28 , wherein the sleeve-like member has a thickness of the material, which is less than or equal to 0.18 mm. 
   
   
       47 . A spacer according to  claim 28 , wherein the nuclear plant is arranged to permit re-circulation of a coolant flow and wherein the spacer is arranged to be located in the coolant flow, the spacer including at least one vane for influencing the coolant flow. 
   
   
       48 . A spacer according to  claim 37 , wherein said vane is formed by a portion of the material, which extends from the first connection portion. 
   
   
       49 . A spacer according to  claim 47 , wherein said vane is formed by a portion of the material, which extends from the first connection portion. 
   
   
       50 . A spacer according to  claim 47 , wherein the sleeve-like member includes a slit, which extends from at least one of the upper edge and lower edge and which permits outward bending of a part of the sleeve-like member for forming said vane. 
   
   
       51 . A spacer according to  claim 48 , wherein said vane is inclined in relation to the longitudinal axis. 
   
   
       52 . A spacer according to  claim 41 , wherein said vane extends outwardly from one of said long sides. 
   
   
       53 . A spacer according to  claim 47 , wherein said vane extends outwardly from one of said long sides. 
   
   
       54 . A spacer according to  claim 28 , wherein the spacer, seen in the direction of the longitudinal axis, has a substantially rectangular shape and includes at least two separate outer edge elements which extend along a respective side of the spacer. 
   
   
       55 . A spacer according to  claim 54 , wherein one of the four corners of the rectangular shape is reduced through the lack of outer sleeve-like member, and that the spacer includes a separate inner edge element, which extends along two of said sides and along said reduced corner. 
   
   
       56 . A spacer according to  claim 55 , wherein the inner edge element includes a vane, which is located at said reduced corner and which is inclined upwardly and inwardly towards a centre of the spacer. 
   
   
       57 . A fuel unit for a nuclear plant including a number of elongated fuel rods and a number of spacers for holding the fuel rods, wherein
 the spacers enclose a number of cells, which each have a longitudinal axis and is arranged to receive one of said fuel rods in such a way that the fuel rod extends in parallel to the longitudinal axis,   each cell is formed by a sleeve-like member, which has an upper edge and a lower edge,   the sleeve-like member includes a number of elongated abutment surfaces, which project inwardly towards the longitudinal axis and extend substantially in parallel with the longitudinal axis for abutment to the fuel rod to be received in the cell;   the lower edge, seen transversely to the longitudinal axis, has a wave-like shape with wave peaks, which are aligned with a respective one of said abutment surfaces, and wave valleys located between two adjacent ones of said abutment surfaces; and wherein   the upper edge, seen transversely to the longitudinal axis, has a wave-like shape with wave peaks, which are aligned with a respective one of said abutment surfaces, and with wave valleys located between two adjacent ones of said abutment surfaces.