Three dimensional printed precision magnets for fuel assembly

Abstract

An improved retention and alignment system for nuclear fuel rods includes an upper nozzle plate and a lower nozzle plate, nuclear fuel rods, each having an upper end and a lower end and extending axially between the upper and lower nozzle plates, a first precision magnet incorporated onto the lower end of the fuel rod, and a plurality of second precision magnets incorporated onto the lower nozzle plate in positions confronting the first precision magnets on the fuel rods. Each first precision magnet has at least one of a magnetic north or south polarity and the second precision magnet has at least one of a magnetic south or north polarity opposite the polarity of the confronting first precision magnet to effect magnetic attraction between the confronting first and second precision magnets. Grids between the upper and lower nozzle plates form cells through which the fuel rods pass. Precision magnets of the same polarity may be positioned laterally along the fuel rods and grid walls in positions confronting each other to repel the fuel rods from the grid walls to maintain fuel rod alignment and prevent contact between the fuel rods and the grids.

1 - 15 . (canceled) 
     
     
         16 . A retention and alignment system for a fuel rod, the retention and alignment system comprising:
 a first nozzle plate;   a second nozzle plate, wherein the fuel rod extends between the first nozzle plate and the second nozzle plate;   a grid positioned between the first nozzle plate and the second nozzle plate, wherein the grid comprises a plurality of grid straps, and wherein the plurality of grid straps define a cell comprising a first surface;   a first precision magnet positioned on the first surface of the cell; and   a second precision magnet positioned on the fuel rod, wherein the second precision magnet is configured to confront the first precision magnet to generate a first repelling force therebetween to maintain a gap between the fuel rod and the first surface of the cell.   
     
     
         17 . The retention and alignment system of  claim 16 , wherein the cell further comprises a second surface, wherein the retention and alignment system further comprises a spring extending from the second surface, and wherein the first repelling force drives the fuel rod into engagement with the spring. 
     
     
         18 . The retention and alignment system of  claim 16 , wherein the cell further comprises a second surface, and wherein the retention and alignment system further comprises:
 a third precision magnet positioned on the second surface of the cell; and   a fourth precision magnet positioned on the fuel rod, wherein the fourth precision magnet is configured to confront the third precision magnet to generate a second repelling force therebetween to maintain a second gap between the fuel rod and the second surface of the cell.   
     
     
         19 . The retention and alignment system of  claim 18 , wherein the first repelling force is along a first axis, and wherein the second repelling force is along a second axis transverse the first axis. 
     
     
         20 . The retention and alignment system of  claim 18 , wherein the cell further comprises a third surface, wherein the retention and alignment system further comprises a spring extending from the third surface, and wherein the first repelling force drives the fuel rod into engagement with the spring. 
     
     
         21 . The retention and alignment system of  claim 18 , wherein the cell further comprises a third surface, and wherein the retention and alignment system further comprises:
 a fifth precision magnet positioned on the third surface of the cell; and   a sixth precision magnet positioned on the fuel rod, wherein the sixth precision magnet is configured to confront the fifth precision magnet to generate a third repelling force therebetween to maintain a third gap between the fuel rod and the second surface of the cell.   
     
     
         22 . The retention and alignment system of  claim 21 , wherein the first repelling force is along a first axis, wherein the second repelling force is along a second axis transverse the first axis, and wherein the third repelling force is along a third axis transverse the second axis. 
     
     
         23 . The retention and alignment system of  claim 16 , wherein the cell further comprises a mixing vane configured to control coolant flow around the fuel rod within the cell. 
     
     
         24 . A retention and alignment system for a fuel rod, the retention and alignment system comprising:
 a first nozzle plate;   a second nozzle plate, wherein the fuel rod extends between the first nozzle plate and the second nozzle plate;   a grid positioned between the first nozzle plate and the second nozzle plate, wherein the grid comprises a plurality of grid straps, and wherein the plurality of grid straps define a cell comprising a first surface;   a sleeve coupled to the fuel rod, wherein the sleeve comprises a polarity; and   a precision magnet positioned on the first surface of the cell, wherein the precision magnet is configured to confront the sleeve to generate a first repelling force between the precision magnet and the sleeve to maintain a gap between the fuel rod and the first surface of the cell.   
     
     
         25 . The retention and alignment system of  claim 24 , wherein the cell further comprises a second surface, wherein the retention and alignment system further comprises a spring extending from the second surface, and wherein the first repelling force drives the fuel rod into engagement with the spring. 
     
     
         26 . The retention and alignment system of  claim 24 , wherein the cell further comprises a second surface, wherein the retention and alignment system further comprises a second precision magnet positioned on the second surface of the cell, and wherein the second precision magnet is configured to confront the sleeve to generate a second repelling force between the second precision magnet and the sleeve to maintain a second gap between the fuel rod and the second surface of the cell. 
     
     
         27 . The retention and alignment system of  claim 26 , wherein the first repelling force is along a first axis, and wherein the second repelling force is along a second axis transverse the first axis. 
     
     
         28 . The retention and alignment system of  claim 26 , wherein the cell further comprises a third surface, wherein the retention and alignment system further comprises a spring extending from the third surface, and wherein the first repelling force drives the fuel rod into engagement with the spring. 
     
     
         29 . The retention and alignment system of  claim 26 , wherein the cell further comprises a third surface, wherein the retention and alignment system further comprises a third precision magnet positioned on the third surface of the cell, and wherein the third precision magnet is configured to confront the sleeve to generate a third repelling force between the third precision magnet and the sleeve to maintain a third gap between the fuel rod and the third surface of the cell. 
     
     
         30 . The retention and alignment system of  claim 29 , wherein the first repelling force is along a first axis, wherein the second repelling force is along a second axis transverse the first axis, and wherein the third repelling force is along a third axis transverse the second axis. 
     
     
         31 . The retention and alignment system of  claim 24 , wherein the cell further comprises a mixing vane configured to control coolant flow around the fuel rod within the cell. 
     
     
         32 . A retention and alignment system for a fuel rod, the retention and alignment system comprising:
 a first nozzle plate;   a second nozzle plate, wherein the fuel rod extends between the first nozzle plate and the second nozzle plate;   a grid positioned between the first nozzle plate and the second nozzle plate, wherein the grid comprises a plurality of grid straps, wherein the plurality of grid straps define a cell comprising a first surface and a second surface;   a first precision magnet positioned on the first surface of the cell, wherein the first precision magnet is configured to interface with the fuel rod to generate a first repelling force therebetween to maintain a first gap between the fuel rod and the first surface of the cell; and   a second precision magnet positioned on the second surface of the cell, wherein the second precision magnet is configured to interface with the fuel rod to generate a second repelling force therebetween to maintain a second gap between the fuel rod and the second surface of the cell.   
     
     
         33 . The retention and alignment system of  claim 32 , wherein the cell further comprises a third surface, wherein the retention and alignment system further comprises a third precision magnet positioned on the third surface of the cell, and wherein the third precision magnet is configured to interface with the fuel rod to generate a third repelling force therebetween to maintain a third gap between the fuel rod and the third surface of the cell. 
     
     
         34 . The retention and alignment system of  claim 32 , wherein the cell further comprises a third surface, wherein the retention and alignment system further comprises a spring extending from the third surface, and wherein the first repelling force drives the fuel rod into engagement with the spring. 
     
     
         35 . The retention and alignment system of  claim 32 , wherein the cell further comprises a mixing vane extending toward the fuel rod, wherein the mixing vane is configured to control coolant flow around the fuel rod within the cell.