Patent Number: 053902211
Section: claims

1. In a boiling water reactor fuel bundle, a debris catcher construction for placement within the flow volume defined by an inlet plenum to the lower tie plate assembly to the upper fuel rod supporting grid comprising: first means including spatially axially separated strainer structures across said plenum for imparting a flow direction (momentum) change to passing water coolant, said first means not forming a continuum across said plenum such that at least one substantially unobstructed flow path is preserved through said first means; and  second means defining a trapping structure for trapping debris separated from said water coolant by said flow direction change imparted by said first means.  said means defining spatially separated structures across said plenum includes a deflecting cone.  said means defining said spatially separated structures is located within a lower tie plate of a fuel bundle between an inlet orifice and said rod supporting grid.  a plurality of upstanding side-by-side fuel rods;  a lower tie plate including a rod supporting grid for supporting said plurality of upstanding side-by-side fuel rods;  means for maintaining said fuel rods in upstanding side-by-side relation;  a channel surrounding said plurality of upstanding fuel rods from the vicinity of said lower rod supporting grid along the length of said fuel rods to form a discrete flow path through said fuel bundle;  an inlet plenum to the lower tie plate assembly to the upper fuel rod supporting grid;  first means defining spatially separated strainer structures across said inlet plenum for imparting flow direction change to passing water coolant, said means defining said spatially separated strainer structure not forming a continuum across said plenum such that at least one substantially unobstructed flow path is preserved through said first means; and  second means defining a trapping structure for the trapping separation of the debris separated from said water coolant by said flow direction change imparted by said first means.  said inlet plenum includes a ring for trapping debris fastened to a portion of said plenum.  said inlet plenum is located in said lower tie plate between an inlet orifice and said rod supporting grid. 2. The invention of claim 1 and wherein: 3. The invention of claim 1 and wherein: 4. In a boiling water reactor fuel bundle comprising in combination: 5. The invention of claim 4 and wherein said spatially separated strainer structures are placed in overlapping relationship across said plenum with axial spatial separation therebetween. 6. The invention of claim 5 and wherein said means defining trapping structures includes solid portions and perforate portions. 7. The invention of claim 4 and wherein: 8. The invention of claim 7 and wherein: