Patent Number: 042082498
Section: claims

1. In combination with a fuel assembly for a nuclear reactor of the type having a plurality of long and slender fuel rods, each of said rods having two ends, said rods being spaced from each other and generally parallel to each other in the lengthwise direction, the improvement comprising a cellular grill engaging one of the ends of each of the fuel rods, all of said grill engaged ends being adjacent to each other at the lengthwise rod ends, a hollow guide post coupled on one end to the grill for movement therewith, said guide post having at least one lengthwise slot-formed therein, said slot extending from the end of the guide post that is spaced from the grill through a portion of the guide post length, a plate mounted within the guide post for movement therewith, a pad disposed generally transverse to the guide post slot, said pad having an aperture formed therein to receive the guide post and to accommodate movement of the guide post in a lengthwise direction relative to said pad, and a plunger within the guide post and secured to the pad, said plunger progressively blocking and unblocking the guide post slot in response to relative motion between the plunger and the guide post. 2. A fuel assembly according to claim 1 further comprising spring means circumscribing said guide post, said spring means being interposed between said grill and said pad. 3. A fuel assembly according to claim 1 wherein said plate further comprises an orifice formed therein to establish fluid communication through said plate in said lengthwise direction. 4. A fuel assembly according to claim 2 wherein said plate further comprises an orifice formed therein to establish fluid communication through the plate. 5. In combination with a fuel assembly for a nuclear reactor of the type having a plurality of long and slender fuel rods, each of said rods having two ends, said rods being spaced from each other and generally parallel to each other in the lengthwise direction, the improvement comprising a cellular grill engaging one of the ends of each of the fuel rods, all of said grill engaged ends being adjacent to each other at the lengthwise rod ends, a hollow guide post coupled on one end to the grill for movement therewith, said guide post having at least one lengthwise slot-formed therein, said slot extending from the end of the guide post that is spaced from the grill through a portion of the guide post length, a pad disposed generally transverse to the guide post slot, said pad having an aperture formed therein to receive the guide post and to accommodate movement of the guide in a lengthwise direction relative to the pad, and a plunger within the guide post and secured to the pad, said plunger progressively blocking and unblocking the guide post slot in response to relative motion between the plunger and the guide post. 6. A fuel assembly according to claim 5 further comprising a plate mounted within the guide posts having an orifice to establish fluid communication through the plate.