Abstract: A method for determining and assuring that the pressure charged in a fuel rod is retained therein after the rod is sealed by welding a hole closed in the fuel rod end plug. The fuel rod end having the open end plug therein is sealed in a plenum chamber of known volume. A helium source then charges a first chamber to a predetermined pressure, and after isolating the helium source, the first chamber is discharged into the plenum chamber and the fuel rod. If a pressure sensor in the system indicates a relatively high reading, the end plug has not permitted gas to pass into the fuel rod. A relatively low reading indicates that the fuel rod has been pressurized and the hole in the end plug is then welded shut. To verify that the end plug is properly sealed, the plenum chamber is vented to a third chamber of known volume and the system pressure is then determined. If such pressure reaches a predetermined high value, the end plug weld is defective.

Abstract: A grid of improved design for a nuclear reactor fuel assembly which includes a multiplicity of interleaved straps enclosed in a peripheral frame which forms a grid of egg-crate configuration. Each cell formed by the grid straps, except those containing control rod guide tubes, supports a fuel rod which is held in place by springs projecting laterally inwardly into each cell from the grid straps. The springs extend parallel to the fuel rods and are spaced at 90.degree. intervals around the rod. Further, each of two adjacent springs contact a fuel rod at two points along its length and each of the other two adjacent springs contact the fuel rod at one point thus imparting strength and flexibility to the fuel assembly containing such grids.

Abstract: A shock absorber system was designed to absorb the energy imparted to doors in a nuclear reactor ice condenser compartment as they swing rapidly to an open position. Each shock absorber which is installed on a wall adjacent each door is large and must absorb up to about 40,000 foot pounds of energy. The basic shock absorber component comprises foam enclosed in a synthetic fabric bag having a volume about twice the foam volume. A stainless steel knitted mesh bag of the same volume as the fabric bag, contains the fabric bag and its enclosed foam. To protect the foam and bags during construction activities at the reactor site and from the shearing action of the doors, a protective sheet metal cover is installed over the shock absorber ends and the surface to be contacted by the moving door.

Abstract: There is disclosed a method for rapid refueling of a nuclear reactor. The upper package including the head and upper internals and control rods of the reactor includes a missile shield and by engagement with the shield is moved to a refueling position in a single lifting operation exposing the core in the lower package. The fuel assemblies are then replaced. The removal of the control rods from the core with the upper package is compensated for by an increase in the concentration of neutron absorber, such as boron including B.sup.10, in the medium in which the core is immersed. Typically, the refueling can take place in a few days, at intervals of two to six months. During refueling a fraction of the assemblies are replaced. Because of the facility for rapid refueling and consequent lower time cycle for refueling, the fuel can be of low enrichment and the concentration of neutron absorber in the reactor coolant medium can be decreased.

Abstract: A swing check valve which includes a valve body having an inlet and outlet. A recess in the valve body designed to hold a seal ring and a check valve disc swingable between open and closed positions. The disc is supported by a high strength wire secured at one end in a support spacer pinned through bearing blocks fixed to the valve body and at its other end in a groove formed on the outer peripheral surface of the disc. The parts are designed and chosen such to provide a lightweight valve disc which is held open by minimum velocity of fluid flowing through the valve which thus reduces oscillations and accompanying wear of bearings supporting the valve operating parts.

Abstract: Apparatus for determining pellet length and end squareness which includes a base supporting a pair of linear variable differential transformers (LVDT) between which a pellet is placed for measuring end squareness. The LVDT's are perpendicularity detectors and each includes appropriate windings contained in a housing and an armature axially slidable therein. The armature is mounted on a shaft having extensions on opposite ends thereof. A swivel plate is attached to one end, while the other end is supported in a framework for the inspection apparatus, the arrangement being such that the housing containing the windings moves axially relative to the stationary armature. When a pellet is placed in position, each detector is advanced toward the pellet until its swivel plate contacts the pellet ends. If the pellet ends are not square, the swivel plates cock at an angle, thereby displacing the windings with respect to the armature.

Abstract: A method of welding tabs projecting outwardly from grip straps in a fuel assembly grid to a control rod guide thimble positioned in a cell in the grid including providing a weld guide having openings therein which receive dimples on the strap when the weld guide is placed in a cell adjacent to the cell containing the control rod guide thimble. THe weld guide includes an opening which falls into alignment with a tab so that when a welding gun electrode is placed through the opening and into contact with a tab, the other electrode is automatically centered on its tab thus permitting accurate spot welding of the parts. To make a second spot weld on the same tab but at a point outwardly from the first spot weld, a second weld guide having an opening therein displaced a greater distance from a reference point on the weld guide, is placed in the same cell and the welding process repeated.

Abstract: A method of accurately verifying the pressure contained in a sealed pressurized fuel rod by utilizing a pressure balance measurement technique wherein an end of the fuel rod extends through and is sealed in a wall of a small chamber. The chamber is pressurized to the nominal (desired) fuel rod pressure and the fuel rod is then pierced to interconnect the chamber and fuel rod. The deviation of chamber pressure is noted. The final combined pressure of the fuel rod and drill chamber is substantially equal to the nominal rod pressure; departure of the combined pressure from nominal is in direct proportion to departure of rod pressure from nominal. The maximum error in computing the rod pressure from the deviation of the combined pressure from nominal is estimated at plus or minus 3.0 psig. for rod pressures within the specified production limits. If the rod pressure is corrected for rod void volume using a digital printer data record, the accuracy improves to about plus or minus 2.0 psig.

Abstract: A hydrolysis column, used to hydrolyze uranium hexafluoride gas with water in an ammonium diuranate conversion process, which includes a pipe having a water inlet, a connector inserted in the pipe intermediate its length, and a gas nozzle connected to the connector to feed uranium hexafluoride gas into the water. Since the uranium hexafluoride gas will freeze at 147.degree. F, the gas nozzle is heated by steam which flows through internal passageways, thus imparting sufficient heat to the nozzle which then acts as a heat sink to maintain the gas in a fluid state. The gas-water mixture is then discharged through the pipe outlet to the next step in the process.

Abstract: A homopolar machine designed to operate as a generator and motor in reversibly storing and transferring energy between the machine and a magnetic load coil for a thermo-nuclear reactor. The machine rotor comprises hollow thin-walled cylinders or sleeves which form the basis of the system by utilizing substantially all of the rotor mass as a conductor thus making it possible to transfer substantially all the rotor kinetic energy electrically to the load coil in a highly economical and efficient manner. The rotor is divided into multiple separate cylinders or sleeves of modular design, connected in series and arranged to rotate in opposite directions but maintain the supply of current in a single direction to the machine terminals. A stator concentrically disposed around the sleeves consists of a hollow cylinder having a number of excitation coils each located radially outward from the ends of adjacent sleeves.

Abstract: A process for welding the adjacent ends of frame members peripherally surrounding the interleaved straps of a fuel assembly grid which includes placing the assembled grid and its frame members into a fixture made to substantially the same dimensions as the outside dimensions of the grid. The side members of the frame are arranged such that a space appears at each of the four corners and a special tool placed in each of the four corner cells of the grid is designed to have an opening which corresponds to the openings formed on each corner of the fixture. After the tooling is placed in each of the four corner cells, the assembled grid and fixture is then placed in welding apparatus such that a welding tip thereof is placed in the tool located in a corner cell.

Abstract: A modular in-core flow filter for capturing potentially harmful debris during cold hydrostatic and hot functional testing of a nuclear reactor. Since testing is carried out before fuel assemblies are placed in the reactor, multiple filters, each being of the same size and configuration, are temporarily installed on the reactor lower core plate. They fill the space which later is occupied by fuel assemblies when the assemblies are installed in an operating position. Each filter includes a square metal base having a single axial opening which desirably covers four holes in the core plate. Fine mesh and coarse mesh screens are secured in the axial opening and the unit is removably attached to the core plate by brackets which extend through the metal base and engage the underside of the core plate but are actuated into position from the upper side of the core plate. When functional flow testing of the primary coolant system has been completed, the filters are removed for subsequent use in other reactors.

Abstract: An improved nuclear fuel composition characterized as a mixture of the dioxide of uranium and plutonium with pores of specified sizes and volumes of each size. The volume of pores of each size are adjusted so that as each group of pores of each size is removed by the nuclear fission induced process of densification, the volume removed is balanced by the volume added by the nuclear fission induced process of solid state swelling. This fuel composition is dimensionally stable in-pile to high burnups because the rate of pore removal is matched to the rate of swelling.

Abstract: A combined fuel assembly and thimble plug gripper for raising and lowering a fuel assembly into a nuclear reactor core, and for lifting and lowering a thimble plug assembly into the fuel assembly, including a vertically movable mast housing a mechanism which causes pivotally mounted fingers on the bottom of the mast to be moved into and out of latching engagement with the nozzle of a fuel assembly when the mast is resting on said assembly. The mast includes a second mechanism which supports second fingers pivotally mounted thereon and actuable by a third mechanism into and out of engagement with a thimble plug assembly suporting plugs adapted to be inserted in control rod guide thimbles in the fuel assembly. The second mechanism further includes an arrangement for lowering or raising the plug assembly respectively into or out of the guide thimbles in the fuel assembly. The apparatus includes control and interlock systems which preclude operation of the mechanisms under certain prescribed conditions.

Abstract: The peripheral blanket of a breeder reactor requires a coolant flow rate which is a varying fraction of that of the central core region. A self-orificing blanket cooling structure which is characterized by a predominance of radial coolant flow, generated by the pressure difference across the blanket, is utilized to supply the necessary cooling. The blanket fuel assemblies are surrounded by perforated cans to allow for radial cross-flow through the blanket region.

Abstract: A superconducting synchronous motor or generator which utilizes separate radiation and damper shields around a superconducting field winding on the machine rotor. The damper shield includes a pair of concentrically disposed cylinders held in radial spaced relationship with each other by pillar type structural members. A liquid metal fills the space between the concentric cylinders and as the rotor, including the cylinders, is accelerated to its operating speed, the liquid metal likewise will reach synchronous speed as a result of viscous drag between the liquid metal and the cylinder walls. During operation, the rotor shielding function is performed by the electrically conducting liquid metal moving at synchronous speed during steady state operation. Current generated in the liquid metal shields the superconducting field winding from alternating flux generated in the armature due to phase imbalance and harmonics.

Abstract: Process and apparatus for simultaneously pressurizing a fuel rod having a plug in one end, welding a plug in the other end and sealing a gas pressurizing orifice therein in a single operation. A weld chamber is provided which accommodates one end of a seal rod having a plug fixed in the rod end by a friction fit. A mechanism pushes the fuel rod into the weld chamber which is then pressurized to force gas through a plug orifice into the fuel rod. During subsequent rotation of the rod, an electrode in the weld chamber forms a weld puddle which bridges the end plug-fuel rod interface and the plug orifice to thereby weld the plug in the rod and seal the plug orifice in a single operation.

Abstract: Two sets of ion exchangers or other means which are capable of reversibly storing borate ions are continuously or semi-continuously utilized to provide a nuclear reactor with a supply of both a highly concentrated boric acid solution and a solution having a very low concentration of boron. The process is essentially a timed-two-cycle flow scheme. During the first cycle, fluid is sent from a high concentration storage tank via a cooler and a first set of ion exchanger to a low concentration storage tank while simultaneously sending fluid from a low concentration storage tank via a heater and a second set of ion exchanger to the high concentration storage tank.

Abstract: A method and apparatus for protecting fuel rods in a nuclear reactor core under conditions of a major break in the coolant inlet piping connected to the reactor inlet nozzle. A multi-venturi protector which includes multiple parallel dislosed venturies is mounted in the inlet nozzle. The characteristics of the venturi protector are such that coolant flow through the protector into the reactor is unimpeded, but reverse flow through the protector is restricted when a break occurs in the inlet piping. The resistance offered to such reverse flow permits reactor coolant and emergency core coolant to remain in contact with the reactor core for a time sufficient to allow the fuel rods to decrease in temperature to a low safe level.

Abstract: A fuel transfer system for moving nuclear reactor fuel assemblies from a new fuel storage pit to a containment area containing the nuclear reactor, and for transferring spent fuel assemblies under water from the reactor to a spent fuel storage area. The system includes an underwater track which extends through a wall dividing the fuel building from the reactor containment and a car on the track serves as the vehicle for moving fuel assemblies between these two areas. The car is driven by a motor and linkage extending from an operating deck to a chain belt drive on the car. A housing pivotally mounted at its center on the car is hydraulically actuated to vertically receive a fuel assembly which then is rotated to a horizontal position to permit movement through the wall between the containment and fuel building areas. Return to the vertical position provides for fuel assembly removal and the reverse process is repeated when transferring an assembly in the opposite direction.