Abstract: A high pressure laser welding method and apparatus enables seam welding of a nuclear fuel rod at hyperbaric pressure. In an automatic process, a loaded fuel rod and an upper end plug are mated within a sealable weld box. A pressure within the weld box is controlled relative to a pressure within the fuel rod, and a laser assembly welds the seam at hyperbaric pressure. Helium flowing through a laser window nozzle during welding prevents soot contamination of the laser window glass and prevents formation of ionic plasma. The upper end plug fuel rod welding operation is thus reduced to a single step and eliminates inspection related tasks with respect to a sealed hole.

Abstract: A fuel bundle and lower tie plate assembly for a nuclear reactor includes a plurality of fuel rods supported between an upper tie plate and a lower tie plate assembly. The lower tie plate assembly includes an upper grid portion and a lower body portion, the upper grid portion having a plurality of fuel rod supporting bosses interconnected by a plurality of webs thus forming flow openings between the bosses. The body portion includes an inlet nozzle and a peripheral wall extending between the bottom nozzle and the upper grid portion to define a flow volume therein. A debris catcher is located within the flow volume and includes a pair of superposed plates, the plates each having a plurality of holes of substantially the same size, shape and pitch, but wherein the holes of one of the pair of plates are offset from the holes of the other of the pair of plates by one half the hole pitch.

Abstract: Leaf-type springs are inserted into slots in an upper tie plate of a nuclear fuel assembly and bear against interior surfaces of the fuel channel to center the upper tie plate within the fuel channel. More robust similarly configured leaf springs are secured in slots in the upper tie plate and are cantilevered for bearing engagement through slots in the fuel assembly channel against the reactor top guide to bias the fuel assemblies toward the control rod. To mount each spring to the upper tie plate, the base of each leaf spring includes a central beam and a pair of outermost beams spaced from the central beam, all beams lying in a common plane. Laterally outwardly directed tabs are provided on the lower ends of the outer beams. Stops are provided intermediate the ends of the outer beams. By inserting the unstressed, unloaded base of the springs into the slots, the outer beams are displaced inwardly into a stressed condition.

Abstract: A debris catching arrangement is disclosed for incorporation within the flow plenum up stream or below the rod supporting grid of the lower tie plate assembly. The device is preferably placed within the lower tie plate flow plenum between the fuel bundle inlet orifice and the rod supporting grid structure supporting the fuel rods; alternate placement can include any inlet channel upstream of the fuel rods including the fuel support casting. The disclosed debris catching designs include successive side-by-side coil springs placed in layers across the tie plate plenum. Preferably, the respective tie plates are placed in alternating directions with a first layer of springs oriented at 90.degree. to an alternate and underlying layer of springs. Multiple layers of such springs are used with four layers being preferred. At their respective crossing points, the springs of adjacent layers are joined--as by welding--with the result that the filter is a solid unitary mass.

Abstract: In a boiling water nuclear reactor fuel bundle, a debris catching arrangement is disclosed for incorporation within the flow plenum up stream or below the rod supporting grid of the lower tie plate assembly. The device is preferably placed within the lower tie plate flow plenum between the fuel bundle inlet orifice and the rod supporting grid structure supporting the fuel rods; alternate placement can include any inlet channel upstream of the fuel rods including the fuel support casting. Paired plates defining offset holes and bosses are utilized. The bosses are supported at plate webbing between the respective holes. The holes are preferably square in plan with appropriately relieved and rounded corners defining the edges of the webbing. The bosses may be cylindrical, square or rectangular in cross-section. In confrontation of plates to form the debris catching grid, each boss from one plate confronts a hole from the remaining plate.

Abstract: To inspect the integrity of pressurization holes in nuclear fuel rod final end plugs, quality assurance apparatus includes an adapter providing a test chamber into which an end plug is inserted. Instrument gas is introduced into the test chamber through an inlet port for flow to the atmosphere through the pressurization hole. A mass flow meter measures the gas flow through the pressurization hole to determine if it is capable of supporting requisite pressurization of a nuclear fuel rod when the end plug is assembled thereto.

Abstract: In an automated first weld apparatus, a transporter conveys nuclear fuel cladding tubes successively to a welding station where a separate end plug is welded to an open end of each tube. Thereafter, the transporter indexes the tubes successsively through a cooldown station where the weld is cooled, to a reader station where a unique end plug serial number is read, and then to a succession of inspection stations where the internal and external weld characteristics are automatically examined. The resulting inspection data is correlated with the associated serial number for record purposes and tested against quality assurance standards pursuant to sorting the tubes into accepted and rejected lots.

Abstract: A velocity limiting device providing greater resistance to motion through a fluid in one direction than in the opposite direction. The device includes a toroidally shaped control member having a smooth generally conical surface on one side for low resistance movement through the fluid in the one direction. On its opposite side the control member is formed with at least one groove providing a concave surface spaced from which is an arrangement of vanes forming a jet for directing a stream of fluid into the groove upon movement in the opposite direction whereby the resultant increase in fluid turbulence increases resistance to rapid movement in this opposite direction.