Patent Number: 051981831
Section: claims

1. An apparatus for close packing of nuclear fuel assemblies, wherein a nuclear fuel assembly has an array of nuclear fuel rods spaced within an envelope with narrow spaces and wider spaces therebetween, said apparatus comprising: (a) said nuclear fuel assembly, and  (b) a plate having an effective amount of neutron absorbing material, said plate further having a thickness permitting insertion within said envelope and between said nuclear fuel rods within said narrow spaces, and having a width and length permitting insertion between any grid spacers within said nuclear fuel assembly.  (a) a releasable lock on said plate.  (a) an elongated member having first and second ends, said first end having a key, said second end rotatably attachable to said plate,  (b) a locking disk attached on said elongated member between said key and said second end, and having a thickness less than a shortest distance between said fuel rods and having a width greater than said shortest distance,  (c) whereby said thickness of said locking disk permits said disk to be inserted between said nuclear fuel rods then locked between said nuclear fuel rods by rotating said locking disk with said key so that said width of said locking disk prevents removal of said locking disc between said nuclear fuel rods.  (a) a retainer attached to an end of said plate near said key and containing said key.  (a) making a plate having an effective amount of neutron absorbing material, said plate further having a thickness permitting insertion within said envelope and between said nuclear fuel rods within said narrow spaces, and having a width and length permitting insertion between any grid spacers within said nuclear fuel assembly, and  (b) said plate between said nuclear fuel rods within said envelope of said nuclear fuel assembly.  (a) releasably locking said plate within said fuel assembly.  (a) a plate having an effective amount of neutron absorbing material,  (b) a releasable lock having  (c) an elongated member having first and second ends, said first end having a key, said second end rotatably attachable to said plate,  (d) a locking disk attached on said elongated member between said key and said second end, and having a thickness less than said narrow space between said fuel rods and having a width greater than said narrow space,  (e) whereby said plate is placed within said envelope and said thickness of said locking disk permits said disk to be inserted between said nuclear fuel rods then locked between said nuclear fuel rods by rotating said locking disk with said key so that said width of said locking disk prevents removal of said locking disc between said nuclear fuel rods.  (a) a retainer attached to an end of said plate near said key and contacting said key. 2. An apparatus as recited in claim 1, further comprising: 3. An apparatus as recited in claim 2, wherein said releasable lock is a rigid lock comprising: 4. An apparatus as recited in claim 3, further comprising: 5. A method for close packing of nuclear fuel assemblies, wherein a nuclear fuel assembly has an array of nuclear fuel rods spaced within an envelope with narrow spaces and wider spaces therebetween, said method comprising the steps of: 6. A method as recited in claim 5, further comprising: 7. An apparatus for close packing of nuclear fuel assemblies, wherein a nuclear fuel assembly has an array of nuclear fuel rods spaced within an envelope with narrow spaces and wider spaces therebetween, said apparatus comprising: 8. An apparatus as recited in claim 7, further comprising: