Abstract: A catalytic recombiner device for reacting two or more molecular species having dilute concentrations in fluids flowing in pipes at elevated temperatures. The species are stable in the bulk fluid, but because of a high electrochemical potential, the species create conditions favorable to stress corrosion cracking in the pipe walls. If the pipe forms a portion of a coolant system, as in a nuclear power plant, the dissolved chemical species are transported and distributed throughout the system with undesirable consequences. To reduce the electrochemical potential, a cartridge having catalytic surfaces is installed in the flow upstream of the component to be protected against stress corrosion cracking. The catalytic surfaces of the cartridge form a small amount of benign reaction product (e.g. water), thereby reducing the concentration of undesirable species.

Abstract: A method and an apparatus for repairing a shroud in which the top guide support ring has been subjected to stress corrosion cracking. The method involves the placement of a plurality of clamps around the outer circumference of the shroud at a plurality of azimuthal positions between jet pump assemblies. The clamps structurally replace the welds that join the top guide support ring to the upper and lower shroud walls. The shroud repair clamps support the top guide, the fuel bundle assemblies and the shroud head. The shroud repair clamps are bolted to the shroud above and below the top guide support ring in a manner which will prevent relative movement across the top guide support ring welds during all normal and upset conditions.

Abstract: An automated monitoring system and method of operation is provided for a nuclear reactor having a pressure vessel containing a reactor core for boiling water to generate steam. A plurality of monitors provide signals for respective monitoring parameters for monitoring operation of the reactor, and a computer includes a data base therein containing predetermined setpoints for the monitoring parameters. The computer identifies abnormal and normal behavior of the monitoring parameters based on the data base, and determines the cause of abnormal behavior of the monitoring parameters using artificial intelligence. A warning is also provided to identify the cause of the monitoring parameter abnormal behavior. And, automatic mitigation action may also be effected.

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 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 strainer structures defining spatially separated straining or obstructing layers imparting to the fluid in the plenum a circuitous flow path. This circuitous flow path causes the two phase separation of the heavier debris from the lighter transporting water by flow direction change with the debris directed and detoured to a trapping structure.

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: An apparatus for loading nuclear fuel rods through spacer grid cells of a fuel bundle includes a handle having at least one elongate clip joined thereto, and a flexible tubular sleeve joined to the clip. The clip rigidly supports the sleeve along its longitudinal axis while allowing the sleeve to unfurl perpendicularly thereto for disassembly from a fuel rod. In several embodiments of the invention, the clip may include a slot for bridging adjacent grid cells during assembly, or the clip may be removably fixedly joined to the handle for allowing easy replacement of the sleeves.

Abstract: In a boiling water reactor fuel bundle, a three dimensional debris catching grid construction is placed within the flow volume defined by the lower tie plate assembly between the inlet nozzle and upper fuel rod supporting grid. A perforated plate is utilized having round holes as small consistent with the prevention of inadvertent closure due crudding and a hole pitch consistent with mechanical integrity requirements. The perforated plate is placed in a three dimensional construction such as a dome, cylinder, pyramid, inverted pyramid or corrugated construction spanning the flow volume of the lower tie plate assembly. As a consequence of this three dimensional grid construction, the total flow through area of the perforations in the metal plate does not introduce appreciable pressure drop in the lower tie plate assembly between the inlet nozzle and the rod supporting grid.

Abstract: The present invention provides a cladding having an outer circumferential substrate, a zirconium barrier layer metallurgically bonded to the inside surface of the substrate and an inner circumferential liner metallurgically bonded to the zirconium barrier. The inner circumferential liner is more ductile than conventional Zircaloy. The low ductility of the inner circumferential liner is obtained by using a zirconium alloy containing a low tin content (e.g. less than 1.2% by weight) and/or a low oxygen content (e.g. less than 1000 ppm). The inner circumferential liner is less than about 25 micrometers thick.

Abstract: An improved tool for removing the highly contaminated inner filter from a control rod drive during a maintenance operation. The tool may also be used to install the inner filter by pushing the inner filter on and locking the spring clip onto flats of the center lug of the control rod drive stop piston. The tool has a collet with flexible fingers which are inserted inside the inner filter while flexed radially inward. After the collet is inserted, a retractable cam with a conical bearing surface is retracted to a position whereat it urges the collet fingers radially outward to clamp the collet onto the inner filter. The locked filter must be rotated before removal. With the inner filter coupled to the collet, the tool is then pulled out to remove the inner filter from the control rod drive.

Abstract: In an automated final weld apparatus, a transporter conveys nuclear fuel-loaded cladding tubes successively to a check station to verify the presence of a plenum spring in the open end of each cladding tube, a reader station where a unique first end plug serial number is read, an evacuation/backfill station where the cladding tube is backfilled with helium, a seam welding station where a final end plug is welded to the cladding tube open end, and a seal weld station where the tube is pressurized with helium through a pressurization hole in the final end plug, whereupon the pressurization hole is welded closed. After checking for helium leakage, the seam weld is inspected in a succession of inspection stations, and, depending on inspection results, the finished nuclear fuel rods are sorted into accepted and rejected lots.

Abstract: A barrier tube of non-circular cross section is arranged in the space between the stainless steel cladding and metal fuel slugs of a liquid metal reactor. The non-circular shape of this barrier design promotes improved thermal bonding in both the cladding/barrier and barrier/fuel interface regions. The non-circular barrier results in three areas with liquid metal thermal bond gaps having an angle which approaches that for a metal fuel pin without a barrier. Thus, the degree of circumferential unbonding will be less than that which results in localized fuel melting during radiation.

Abstract: A method and apparatus measure squareness of an end of a rod relative to a longitudinal centerline axis thereof without requiring rotation of the rod. The apparatus includes a flat plate mounted substantially perpendicularly to the rod centerline axis. The method positions the plate in abutting contact with the rod end, and a tilt angle of the plate in abutting contact with the rod end is measured for determining squareness of the rod end.

Abstract: An effluent container has two halves which fit together to form a cylinder, open at the top, for catching residual contaminated water falling from the control rod drive (CRD) housing under the influence of gravity when the seal between the CRD housing and the CRD is broken. The container has an aperture which fits around the extension rod that supports the CRD when the mounting bolts are removed. The container halves are held together by elastic cords stretched between hooks on the side-walls. The effluent container has L-shaped slots which hook onto the bracing bolts of the sway brace system to support the container in position for catching falling water. Spilled water drains out of the container to a sump.

Abstract: A tool set and a method of using those tools in combination is disclosed that are especially well adapted to the function of rearranging and/or replacing the control rods and fuel supports in a boiling water reactor. The tool set includes a grapple that is capable of simultaneously picking up both a control rod and its associated fuel support. A separate unlatching tool is provided for pulling the control rod's release handle in order to decouple the control rod from a control rod drive. A storage rack that may be mounted in the reactor pressure vessel is provided for storing a fuel support and a pair of control rods when the positions of selected control rods are being shifted about the reactor core area. In the method aspect of the invention, the unlatching tool is used to pull the control rod's release handle. Thereafter, the grapple lifts the control rod and its associated fuel support as a unit.

Abstract: An ultrasonic method of inspecting repaired stub tubes in a boiling water reactor. The top and bottom ends of each stub tube are respectively welded to the corresponding control rod drive housing and to the bottom head of the reactor pressure vessel. Under certain conditions, a crack can form in the heat-affected zone of the stub tube adjacent to the upper weld, necessitating repair by installing a mechanical seal. A probe inserted in the control rod drive housing has transducers which transmit pulsed ultrasonic energy toward a machined surface-air gap interface disposed to reflect the pulse trains generally axially through the stub tube. The radial and azimuthal dimensions of a radial crack in the stub tube are determined in dependence on which pulsed trains are reflected back to the probe by the crack via the interface.

Abstract: A method for preventing or reducing the formation of Co-60 contaminated material on the surfaces of a cooling water circuit of a nuclear reactor. The method is carried out during shutdown of the reactor. First, Co-60 contaminated material formed on the surfaces of the cooling water circuit is chemically removed. Then at least one iron compound is added to the cooling water in an amount sufficient to scavenge cobalt from the cooling water. Thereafter, oxygen is injected into the cooling water to provide a dissolved oxygen concentration sufficient to form an oxide film on the surfaces of the cooling water circuit. The oxide film so formed is substantially free of Co-60 isotope. This treatment reduces the radiation hazard to nuclear reactor personnel.

Abstract: A spacer array is disclosed in which alternating cells are disposed at differing elevations. In a preferred octagonal spacer cell array, alternate fuel rods within the rows and columns of the fuel bundle matrix are surrounded by octagonal spacer cells at a first elevation. Likewise, and in the same preferred octagonal spacer array, the remaining alternate fuel rods within the rows and columns of the fuel bundle matrix are surrounded by octagonal spacer cells at a second elevation. The octagonal spacer cells of the spacer array at one level adjoin the octagonal spacer cells of the spacer array at an adjacent level. Specifically, each octagonal spacer cell has the top and/or the bottom of as many as four of its eight sides disposed for joinding with one side of as many as four octagonal cells in an adjacent cell layer. Each cell has approximately 0.6 of an inch height, or one-half the 1.2 inch height of the prior art.