Abstract: A miniature, unmanned aircraft having interchangeable data handling modules, such as sensors for obtaining digital aerial imagery and other data, and radio transmitters and receivers for relaying data. The aircraft has a microprocessor for managing flight, remote control guidance system, and electrical supply system. The data handling modules have an aerodynamic housing and manual fasteners enabling ready installation and removal. One or more data acquiring sensors or data transferring apparatus and support equipment such as batteries and communications and power cables are contained within the module. A plurality of different modules are preferably provided. Each module, when attached in a preferred location below the wing, does not significantly alter the center of gravity of the airframe. Preferably, each module contains the supervisory microprocessor so that the microprocessor need not be part of the airframe.

Abstract: Control device for a cooling circuit which enables a pressure tank of a reactor to be cooled even when a serious failure occurs, without having to resort to the use of external energy. One or more rods is disposed below a bottom cap of the reactor pressure tank. Each rod is connected to an emergency cooling system by a transmission system. The end of each rod opposite the transmission system is arranged at a distance of approximately 3 cm from the bottom cap. A hydraulic system is used advantageously as a transmission system. Each rod is placed vertically on a hydraulic cylinder arranged in a parallel position with respect to the axis of the reactor pressure tank, and each cylinder is connected to the emergency cooling system. When several hydraulic cylinders are used, they are connected to each other by hydraulic lines.

Abstract: A control rod (2) for boiling water reactor comprising four absorber blades (6, 7, 8, 9) which form an orthogonal cross with a cruciform centre (10). The width of the absorber blades coincides with the radial direction of the control rod and the length of the absorber blades coincides with the axial direction of the control rod. Each one of the absorber blades comprises an absorber material distributed in the longitudinal direction, whereby a mean value of the quantity of absorber material per unit of length of the control rod is smaller in the upper part of the control rod than in the lower part thereof. Each one of the absorber blades comprises in its upper part (15) an inner part arranged radially inside an outer part, where the outer part is provided with absorber material whereas the inner part lacks absorber material, whereby said inner part in at least some portion constitutes at least one-fourth of the width of the absorber blade.

Abstract: An improved grid for use in a fuel assembly of a nuclear reactor includes a plurality of straps that are interconnected with one another in a lattice fashion to define a plurality of cells, with the straps being configured to include a plurality of relatively more compliant springs and a plurality of relatively less compliant dimples, whereby each cell includes only one pair of springs and one pair of dimples disposed therein. The springs and dimples are contoured to engage a fuel rod or a thimble tube disposed within the cell. Each spring directly confronts one of the dimples to provide confronting pairs of features that engage the fuel rods or thimble tubes, with each cell including two pairs of confronting features. The ligaments of the springs and dimples extend in a direction generally perpendicular to the direction of coolant flow through the reactor in order to minimize pressure drop.

Abstract: A fluid pump utilizing a canned rotor and canned stator is provided. The fluid pump has increased insulative properties over past “spool-type” pumps and has an increased ability to cool the stator, making it suitable for high temperature applications. A nuclear reactor is also provided. The reactor comprises a reactor vessel, that contains a nuclear fuel, control rods, reactor coolant and a reactor coolant pump for providing the reactor coolant to a steam generator. In a preferred embodiment, a steam generator is also provided inside the reactor vessel.

Abstract: The present invention provides a boiling water reactor nuclear power plant in which a reactor core support plate, upper grid plate, and a reactor core consisting of fuel assemblies supported by these plates are provided in the inner base portion of a nuclear reactor pressure vessel. Control rod guide tubes and a reactor core shroud are positioned over the upper grid plate, and a control rod drive mechanism is provided further above same, whereby the control rods can be inserted from above the reactor core, and natural circulation of cooling water inside the reactor can be achieved by means of a chimney effect of the control rod guide tubes. According to the above structure, there can be provided a compact and economical nuclear power plant.

Abstract: A lips-type multi-purposed spacer grid for supporting fuel rods within a nuclear fuel assembly is disclosed. In the spacer grid, the fuel rods are in contact with dimples and water strider-type springs in an equiangular surface contact manner. The spacer grid distributes load, applied to the springs, to the entire structure of its inner strips, thus reducing peak stress at the contact surfaces between the fuel rods and the springs and diminishing vibration of the fuel rods, and thereby reducing possible fretting wear of the fuel rods due to hydraulic vibration of the fuel rods. The spacer grid also enlarges the allowable elastic range of the springs, and allows the springs to soundly support the fuel rods by using residual spring force. The spacer grid has mixing blades capable of minimizing pressure loss and flow interference, so that the fuel rod cooling efficiency of the nuclear fuel assembly is improved.

Abstract: A piping support wedge apparatus for a jet pump in a nuclear reactor is provided. In an exemplary embodiment, the wedge apparatus includes a first tapered wedge segment having a first end portion and a second end portion and a second tapered wedge segment having a first end portion and a second end portion. The first and second wedge segments are joined at the first ends portions to form a substantially U-shaped body. The wedge apparatus also includes a slot defined by an area between the first and second wedge segments and extending from the first end portions to the joined second end portions of the wedge segments.

Abstract: A fuel assembly in accordance with the present invention comprises a plurality of first fuel rods and a plurality of second fuel rods having a length shorter than a length of the first fuel rod, and these two kinds of fuel rods are arranged in a fuel rod array of 10 rows by 10 columns. Two water rods are arranged in regions capable of arranging 8 fuel rods. The second fuel rods are not arranged in the outermost tier of the fuel rod array. Which satisfies the following conditions, that is, B≧60  (Equation 1) 15≦n≦20(n: integer)  (Equation 2) Awr/Ach≦0.149  (Equation 3) Lp/Lf≧11/24  (Equation 4) Awr/Ach≧(3.00×10−4×n2+6.00×10−4×n−1.2×10−2)×(Lp/Lf−1)+1.75×10−1  (Equation 5) Awr/Ach≦(8.63×10−4×n2−6.09×10−2×n+1.33×10−1)×(Lp/Lf−8.

Abstract: The spacer/water rod retention assembly includes a clip secured to the spacer having a slot perimetrically bounded both axially and laterally spaced portions of the clip. A resilient tab projects from one side portion into the slot. A water rod has a projecting tab which, upon relative rotation of the spacer and water rod, engages and deflects the clip tab to enable the water rod tab to reside in the clip slot. When the clip tab returns to its initial position, substantial relative rotation between the water rod and spacer is precluded and axial connection between the spacer and water rod is assured. In another form, the water rod tab projects into a slot of the clip. An adjacent water rod prevents rotation of the water rod tab in the opposite direction, thereby capturing the spacer and water rod and preventing relative axial movement.

Abstract: A computerized method for expanding the operating domain of a boiling water nuclear reactor that permits safe operation of the reactor at core flows lower than normal operating parameters is provided. The operating domain is characterized by a map of the reactor thermal power and core flow. The computerized method includes determining by computer simulation a load line characteristic that is elevated over normal operating parameters and that increases reactor performance over normal operating parameters, performing safety evaluations by computer simulation at the elevated load line to determine compliance with safety design parameters, and performing operational evaluations by computer simulation at the elevated load line.

Abstract: A spacer grid for use in a nuclear fuel assembly has double-deflected vanes that guide an axial flow of coolant around fuel rods and thereby generate swirl flow. The vanes each have a double bend projecting upwardly from first inner straps and projecting toward one fuel rod. The vanes are sufficiently wide at their bases to prevent inadvertent deformation due to contact with fuel rods during an insertion of fuel rods into the cells. The vanes also make a smooth variation in the cross-sectional area of the coolant channel at the outlet of the spacer grid, thus reducing a loss of pressure during reactor operation.

Abstract: A spacer grid used for placing and supporting fuel rods in nuclear reactor fuel assemblies is disclosed. The spacer grid of this invention has a plurality of grid springs designed to have an optimal shape of their vertical support parts, thus reducing fretting wear of the fuel rods caused by contact of the fuel rods with the grid springs. The grid spring has a vertical support part and a fuel rod support part. The vertical support part includes upper and lower base parts extending downward and upward from the central portions of the top and bottom edges of an opening formed at the central portion of a unit strip, and two bridge parts branched from the upper base part and extending symmetrically downward until they are united at the lower base part. The fuel rod support part includes a conformal support part brought into surface contact with the external surface of a fuel rod.

Abstract: A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube.

Abstract: A method for expanding the operating domain of a boiling water nuclear reactor that permits safe operation of the reactor at low core flows is described. The operating domain is characterized by a map of the reactor thermal power and core flow. In an exemplary embodiment, the method for expanding the operating domain of a boiling water nuclear reactor permits operation of the reactor between about 120 percent of rated thermal power and about 85 percent of rated core flow to about 100 percent of rated thermal power and about 55 percent of rated core flow. The method includes determining an elevated load line characteristic that improves reactor performance, performing safety evaluations at the elevated load line to determine compliance with safety design parameters, and performing operational evaluations at the elevated load line. The method also includes defining a set of operating conditions for the reactor in an upper operating domain characterized by the elevated load line.

Abstract: A nuclear fuel assembly includes a fuel bundle resting on a lower tie plate. The lower tie plate includes a grid having raised bosses disposed in a rectilinear array for receiving the end plugs of the fuel rods and webs interconnecting the bosses. Between the raised bosses and the end plugs, there is disposed a filter plate having holes registering with the holes through the bosses for receiving the end plugs and apertures providing an approximate 40% open area through the filter plate. The webs of the tie plate grid are recessed from the upper edges of the bosses, facilitating flow through the apertures of the filter plate.

Abstract: A safe start-up of a boiling water reactor is achieved when two conditions are adhered to and monitored when the control rods are being moved out of the core: First, the drive of a control rod should be activated only when the directly and diagonally adjacent control rods remain at rest simultaneously, and, second, when all the directly adjacent control rods are still in the fully moved-in initial position.

Abstract: An unirradiated nuclear fuel assembly transport canister that includes a clamshell type fuel assembly inner liner that has interior dimensions that closely conform to the outer envelope of the fuel assembly to be transported and exterior dimensions that conform to a generic overpack tubular container. The liner is inserted into the overpack tubular container which is in turn supported by a shock absorbing suspension system within a birdcage frame.

Abstract: Before welding, the plug and the sleeve of the fuel rod being in the welding position at the welding station, the sleeve and the plug of the fuel rod are rotated about their common axis with the aid of rotation means, images are taken along the periphery of the fuel element to obtain digitized images, the digitized images are analyzed to determine the position of the joint plane between the sleeve and the plug of the fuel rod, and the rotation of the fuel element is verified. It is deduced whether it is possible to perform the welding or not. If welding is performed, images are taken of the fuel element along the periphery of the fuel element, in the vicinity of a joint line between the sleeve and the plug, to obtain digitized images which are analyzed to check the conformance of a weld made along the joint line.

Abstract: A MOX nuclear fuel assembly employable either for a thermal neutron reactor employing UO2 as the nuclear fuel and light water as the moderator/coolant or for a thermal neutron reactor employing the MOX fuels as the nuclear fuel and light water as the moderator/coolant is provided with only one kind of MOX nuclear fuel rods each of which has relatively large magnitude of the enrichment grade of the fissionable Pu-s or Pu239 and Pu241, the quantity of the MOX nuclear fuel rods being relatively small.