Debris filtering arrangement for nuclear fuel assembly bottom nozzle and bottom nozzle including same

Abstract

A filtering arrangement for use in a bottom nozzle of a fuel assembly in a nuclear reactor includes a top surface, a bottom surface, a plurality of vertical wall portions arranged in a generally squared grid-like pattern which extend between the bottom surface and the top surface and define a plurality of non-circular passages extending between the bottom surface and the top surface through the arrangement, and a plurality of first debris filters which are each positioned between the top surface and the bottom surface to generally span across a respective one of the plurality of passages.

What is claimed is: 
     
         1 . A filtering arrangement for use in a bottom nozzle of a fuel assembly in a nuclear reactor, the filtering arrangement comprising:
 a top surface;   a bottom surface;   a plurality of vertical wall portions arranged in a generally squared grid-like pattern which extend between the bottom surface and the top surface and define a plurality of non-circular passages extending between the bottom surface and the top surface through the arrangement; and   a plurality of first debris filters, each debris filter being positioned between the top surface and the bottom surface to generally span across a respective one of the plurality of passages.   
     
     
         2 . The filtering arrangement of  claim 1 , wherein each first debris filter comprises a hollow pyramid or hollow cone-like structure formed from a lattice structure which is sized and configured to minimize resistance in regard to coolant flow through the lattice structure. 
     
     
         3 . The filtering arrangement of  claim 2 , wherein when viewed from directly above the filtering arrangement or directly below the filtering arrangement the lattice structure of each first debris filter is arranged so as to form a first squared grid-like pattern. 
     
     
         4 . The filtering arrangement of  claim 2 , wherein at least one first debris filter narrows from bottom to top. 
     
     
         5 . The filtering arrangement of  claim 2 , wherein at least one first debris filter narrows from top to bottom. 
     
     
         6 . The filtering arrangement of  claim 1 , further comprising a plurality of second debris filters which are each positioned between the top surface and the first debris filter to generally span across a respective one of the plurality of passages. 
     
     
         7 . The filtering arrangement of  claim 6 , wherein each first debris filter comprises a hollow pyramid or hollow cone-like structure formed from a lattice structure which is sized and configured to minimize resistance in regard to coolant flow through the lattice structure, and
 wherein each second debris filter comprises a hollow pyramid or hollow cone-like structure formed from a lattice structure which is sized and configured to minimize resistance in regard to coolant flow through the lattice structure.   
     
     
         8 . The filtering arrangement of  claim 7 , wherein when viewed from directly above the filtering arrangement or directly below the filtering arrangement the lattice structure of each second debris filter is arranged so as to form a second squared grid-like pattern. 
     
     
         9 . The filtering arrangement of  claim 8 , when viewed from above, the second squared grid-like pattern is offset a distance from the first squared grid-like pattern. 
     
     
         10 . The filtering arrangement of  claim 7 , wherein at least one first debris filter narrows from bottom to top and wherein at least one second debris filter narrows from bottom to top. 
     
     
         11 . The filtering arrangement of  claim 7 , wherein at least one first debris filter narrows from top to bottom and wherein at least one second debris filter narrows from top to bottom. 
     
     
         12 . A bottom nozzle assembly for use in a fuel assembly in a nuclear reactor, the bottom nozzle assembly comprising:
 a generally rectangular skirt portion; and   a filtering arrangement as recited in  claim 1  coupled to the generally rectangular base portion.   
     
     
         13 . A bottom nozzle assembly for use in a fuel assembly in a nuclear reactor, the bottom nozzle assembly comprising:
 a generally rectangular skirt portion; and   a filtering arrangement as recited in  claim 6  coupled to the generally rectangular base portion.