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 system, comprising:
 a first fuel assembly, comprising:
 a first nozzle plate; 
 a second nozzle plate; and 
 a first grid positioned between the first nozzle plate and the second nozzle plate, wherein the first grid comprises first grid straps, wherein the first grid straps define first cells, wherein first fuel rods are configured to extend through the first cells, wherein the first grid straps comprise a first grid strap, and wherein the first grid strap comprises a first precision magnet; and 
   a second fuel assembly, comprising:
 a third nozzle plate; 
 a fourth nozzle plate; and 
 a second grid positioned between the third nozzle plate and the fourth nozzle plate, wherein the second grid comprises second grid straps, wherein the second grid straps define second cells, wherein second fuel rods are configured to extend through the second cells, wherein the second grid straps comprise a second grid strap, wherein the second grid strap comprises a second precision magnet; 
   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 first fuel assembly and the second fuel assembly.   
     
     
         17 . The system of  claim 16 , wherein the first grid strap further comprises a first spring configured to engage a fuel rod of the first fuel rods. 
     
     
         18 . The system of  claim 17 , wherein the first grid straps further comprise a third grid strap comprising a second spring, wherein the first cells comprise a first cell that comprises the first grid strap and the third grid strap, and wherein the first spring and the second spring co-operatively engage the fuel rod to secure the fuel rod within the first cell. 
     
     
         19 . The system of  claim 16 , wherein the first grid strap defines a first plane, wherein the second grid strap defines a second plane, and wherein the first plane is parallel to the second plane. 
     
     
         20 . The system of  claim 16 , wherein:
 the first grid strap defines a first upper portion and a first lower portion;   the first precision magnet is located at the first upper portion;   the first grid strap further comprises a third precision magnet located at the first lower portion;   the second grid strap defines a second upper portion and a second lower portion;   the second precision magnet is located at the second upper portion;   the second grid strap further comprises a fourth precision magnet located at the second lower portion; and   the third precision magnet is configured to confront the fourth precision magnet to generate a second repelling force therebetween to maintain the gap between the first fuel assembly and the second fuel assembly.   
     
     
         21 . A system, comprising:
 a first fuel assembly comprising a first grid, wherein the first grid comprises first grid straps, wherein the first grid straps define first cells, wherein first fuel rods are configured to extend through the first cells, wherein the first grid straps comprise a first portion of grid straps extending along a perimeter of the first fuel assembly, and wherein each first grid strap of the first portion of grid straps comprises a first precision magnet; and   a second fuel assembly comprising a second grid, wherein the second grid comprises second grid straps, wherein the second grid straps define second cells, wherein second fuel rods are configured to extend through the second cells, wherein the second grid straps comprise a second portion of grid straps extending along a perimeter of the second fuel assembly, and wherein each second grid strap of the second portion of grid straps comprises a second precision magnet;   wherein the second precisions magnet are configured to confront the first precision magnets to generate first repelling forces therebetween to maintain a gap between the first fuel assembly and the second fuel assembly.   
     
     
         22 . The system of  claim 21 , wherein the first portion of grid straps comprise a first grid strap, and wherein the first grid strap comprises a first spring configured to engage a fuel rod of the first fuel rods. 
     
     
         23 . The system of  claim 22 , wherein the first grid straps further comprise a third grid strap comprising a second spring, wherein the first cells comprise a first cell that comprises the first grid strap and the third grid strap, and wherein the first spring and the second spring co-operatively engage the fuel rod to secure the fuel rod within the first cell. 
     
     
         24 . The system of  claim 21 , wherein the first portion of grid straps define a first plane, wherein the second portion of grid straps define a second plane, and wherein the first plane is parallel to the second plane. 
     
     
         25 . The system of  claim 21 , wherein:
 the first portion of grid straps comprise a first grid strap that defines a first upper portion and a first lower portion;   the first precision magnet of the first grid strap is located at the first upper portion;   the first grid strap further comprises a third precision magnet located at the first lower portion;   the second portion of grid straps comprise a second grid strap that defines a second upper portion and a second lower portion;   the second precision magnet of the second grid strap magnet is located at the second upper portion;   the second grid strap further comprises a fourth precision magnet located on the second lower portion; and   the third precision magnet is configured to confront the fourth precision magnet to generate a second repelling force therebetween to maintain the gap between the first fuel assembly and the second fuel assembly.   
     
     
         26 . A system, comprising:
 a first fuel assembly, comprising:
 a first grid comprising first grid straps, wherein the first grid straps define a first cell comprising a first grid strap and a second grid strap, wherein the first grid strap comprises a first precision magnet; and 
 a second grid comprising second grid straps, wherein the second grid straps define a second cell comprising a third grid strap and a fourth grid strap, wherein a first fuel rod extends through the first cell and the second cell, and wherein the third grid strap comprises a second precision magnet; and 
   a second fuel assembly, comprising:
 a third grid comprising third grid straps, wherein the third grid straps define a third cell comprising a fifth grid strap and a sixth grid strap, wherein the fifth grid strap comprises a third precision magnet; and 
 a fourth grid comprising fourth grid straps, wherein the fourth grid straps define a fourth cell comprising a seventh grid strap and an eighth grid strap, wherein a second fuel rod extends through the third cell and the fourth cell, and wherein the seventh grid strap comprises a fourth precision magnet; 
   wherein the first precision magnet is configured to confront the third precision magnet to generate a first repelling force therebetween to maintain a gap between the first fuel assembly and the second fuel assembly; and   wherein the second precision magnet is configured to confront the fourth precision magnet to generate a second repelling force therebetween to maintain the gap between the first fuel assembly and the second fuel assembly.   
     
     
         27 . The system of  claim 26 , wherein the first grid strap comprises a first spring, wherein the third grid strap comprises a third spring, and wherein the first spring and the third spring are configured to engage the first fuel rod. 
     
     
         28 . The system of  claim 27 , wherein the second grid strap comprises a second spring, wherein the fourth grid strap comprises a fourth spring, and wherein the first spring, the second, the third spring, and the fourth spring co-operatively engage the first fuel rod to secure the first fuel rod within the first cell and the second cell. 
     
     
         29 . The system of  claim 26 , wherein the first grid strap and the third grid strap define a first plane, wherein the fifth grid strap and the seventh grid strap define a second plane, and wherein the first plane is parallel to the second plane. 
     
     
         30 . The system of  claim 26 , wherein:
 the first grid strap defines a first upper portion and a first lower portion;   the first precision magnet is located at the first upper portion;   the first grid strap further comprises a fifth precision magnet located at the first lower portion;   the fifth grid strap defines a second upper portion and a second lower portion;   the third precision magnet is located at the second upper portion;   the fifth grid strap further comprises a sixth precision magnet located at the second lower portion; and   the fifth precision magnet is configured to confront the sixth precision magnet to generate a third repelling force therebetween to maintain the gap between the first fuel assembly and the second fuel assembly.