Abstract: A method and system for suppressing artifacts in a CT generated image are described. With respect to artifacts resulting from X-ray beam photon starvation conditions, and in accordance with one embodiment of the method, the steps of determining a minimum value X-ray beam flux for a projection data set and dynamically DC adjusting the projection data based on the determined minimum X-ray beam flux are performed.

Abstract: The present invention, in one form, is an apparatus for performing image reconstruction using data obtained by a helical scan. In reconstructing an image in accordance with the present invention, projection data arrays corresponding to data planes associated with the slice to be imaged are generated. Weighting factors are then applied to the data arrays to assign a weight to each particular data element thereby creating a weighted projection data array. The weighted projection data array is then filtered and back projected to create an image data array from which an image slice is generated. In accordance with the present invention, the weighting function used in creating the weighted projection data array is based upon a plane of reconstruction which is not necessarily perpendicular to the z-axis.

Abstract: The present invention, in one form, is an apparatus for performing image reconstruction using data obtained by a dual beam helical scan. In reconstructing an image in accordance with the present invention, projection data from each fan beam measurement is weighted by weighting factors to obtain a reconstructed slice. The data arrays selected and weighting factors applied vary depending on the table speed and the detector spacing measured at the axis of gantry rotation, i.e., the detector z spacing.

Abstract: The present invention, in one form, utilizes a region of reconstruction ROR in reconstructing an image from projection data. Particularly, once the region of reconstruction is established, a weighting function which is either a linear interpolation or a non-interpolation can be used. If 3.pi. of projection data is used, the weighting function can be divided into three parts. Each part corresponds to .pi. projection views. For a 50% overlapped reconstruction, the entire weighting functions advance .pi. degrees at a time, which synchronizes very well with the boundaries of the weighting functions. Section 1(S.sub.1) will contain projection views from 0 to .pi., section 2 (S.sub.2) contains views from .pi. to 2.pi., and section 3 (S.sub.3) contains views from 2.pi. to 3.pi.. In section S.sub.1, the weighting function is a ramp-up function, in section S.sub.2 the weighting function is a constant, and in section S.sub.3 the weighting function is ramped down.

Abstract: A self-aligning seal system for use in carrying out maintenance services in a nuclear fission reactor plant is disclosed. The self-aligning seal system enables an operator to block off openings in the lower portion of a water filled reactor pressure vessel for maintenance service in an underlying dry field without draining the coolant water from the reactor pressure vessel.

Abstract: A system for measuring water level includes a reactor pressure vessel containing a core and steam separator assembly, with the vessel being filled with water to a nominal level above the core. A reference leg contains a column of water having a reference level disposed above the nominal level, and a first variable leg has a first tap disposed in the vessel below the reference and nominal levels. A first monitor is disposed between the reference leg and the first leg for determining differential pressure therebetween to indicate level of the water in the vessel above the first tap. A second variable leg includes a second tap in the vessel below the first tap, and a second monitor is disposed between the first and second legs for determining differential pressure therebetween to indicate level of water in the vessel between the first and second taps when the water level falls below the first tap.

Abstract: A part length fuel rod tip and group of tip grasping tools is set forth for the removal, inspection and replacement of part length fuel rods from a fuel bundle having a part length rods interspersed with a majority of conventional full length rods. The part length fuel rod tip includes a longitudinal keyway allowing torque to be exerted on the fuel rod and a horizontal slot enabling grasping of the fuel rod for vertical withdrawal and replacement movement of the fuel rod. The tools include a torque socket for applying high torque forces to the part length rod for unscrewing the rod when the rod becomes stuck at its threaded connection to the lower tie plate, a tip grasping tool for permitting normal unscrewing torque and grasping for vertical withdrawal and replacement, and finally a tool having both high torque and grasping characteristics.

Abstract: A method and apparatus for testing the proper operation of the optical elements in the optical detection circuit of an electronic register in an energy meter. The light emitter circuit is periodically pulsed adequate to turn the emitters to the on condition, and a comparison circuit is provided in which the voltage across a monitor point in circuit with the light emitters and a switching circuit is monitored both before and after each pulse. The absence of a voltage change upon pulsing the light emitter circuitry is used to generate a first error or failure signal. The light detector is read prior to each pulse to determine if unprogrammed light is being received prior to the pulsing of the light emitter as an indication of tampering with the accurate reading of the energy meter, and a second error signal is generated in response to unprogrammed light.

Abstract: In a fuel bundle for a boiling water nuclear reactor, modification of the spacers at the peripheral spacer band is made to maintain a more uniform spacing of the peripheral fuel rods from the channel walls to avoid critical power limitations. The conventional fuel bundle construction include a plurality of side-by-side sealed vertically disposed nuclear fuel rods in a square array supported at a lower tie plate, at least some of the fuel rods fastened to an upper tie plate, and held in designed spaced apart relation as a unitary mass by intermittent vertically placed spacers. A square sectioned channel surrounds the upper tie plate, the lower tie plate, and the fuel rods and spacers therebetween. The square sectioned channel functions to confined fluid flow interior of the fuel bundle between the tie plates and through the fuel rods. At the same time, the channel separates a core bypass region exterior of the channel having high moderator density from the flow path interior of the fuel bundle.

Abstract: Disclosed is a reference electrode probe for employment in monitoring electrochemical potentials. The inventive electrode probe comprises an elongate alumina tube having a closed distal end and a flanged open proximal end, there being at least one hole, and preferably two holes, penetrating through said tube at its closed distal end. An elongate silver electrode coated with silver chloride is housed atactilely within said alumina tube. Zirconia cloth is disposed in the closed distal end of said alumina tube and covers the hole in said alumina tube, and extended up to and may be spaced-apart from said silver electrode. A silver connector is housed atactilely within said alumina tube to its opening, and has a recess at its distal end into which said coated silver electrode is fitted and a threaded recess at its proximal end at the alumina tube opening. An insulated silver alloy rod having a distal end is threaded into the proximal recess of said silver connector.

Abstract: Stator coils for linear flow electromagnetic induction pumps for pumping liquid metal circulating through a hydraulic system are provided with advantageous deployments of coil power terminals and leads.

Abstract: An electronic watthour meter is digitally configurable to operate as several different types of watthour meters for metering electrical energy from a variety of different electric utility services. Automatic scaling of line input currents is provided to scale the voltage input to an analog to digital converter over selected ranges such that low level and high level input signals are measured in an optimum range. A digital signal processor is employed to calculate values for metered electrical energy and output pulses, each proportional to a quantum of energy flowing in the circuit being metered. The processor calculates the value of DC offset errors inherent in the various analog circuits of the meter and uses that value in the calculation of metered electrical energy to compensate for such offset errors. The meter employs automatic and manually initiated test functions for testing the operation of the processor and other critical circuits in the meter.

Abstract: A system for monitoring the radioactivity of a liquid waste stream includes a pair of tanks into which the liquid waste stream is directed during alternating fill cycles. At the conclusion of each fill cycle, the liquid waste is recirculated through the chamber of a radioactivity monitor. A pair of opposed radiation detectors, external to the chamber, generate activity measurements to a controller indicative of the radionuclide concentration levels in the liquid waste. The tanks are then emptied either to the environment or back to a decontamination facility for further processing depending on the indicated radionuclide concentration level. System operation, including periodic servicing of the monitor, is automatically coordinated by the controller to avoid interruption of the liquid waste stream filling the tanks.

Abstract: A tool is disclosed for assembling or disassembling an endcap into or out of a housing. The housing includes a distal end, an intermediate portion, and a receptacle disposed in the distal end. The tool includes a hook removably joinable to the endcap, and a clamp removably joinable to the housing intermediate portion. The hook is jacked relative to the clamp for translating the endcap relative to the receptacle for either assembling or disassembling the endcap into or out of the housing.

Abstract: A fuel pellet retainer spring assembly is disclosed for insertion to the open unsealed end of a fuel rod. The assembly includes a locking sleeve having a normal radial diameter exceeding the inside radial diameter of the fuel rod cladding. This sleeve is compressed to a diameter less than the inside diameter of the fuel rod cladding. Thereafter, the sleeve is inserted. In the preferred embodiment, a washer and coil spring precedes the sleeve into the fuel rod. The sleeve is inserted and thereafter allowed to expand and frictionally hold to the inside wall of the cladding. When the sleeve is in place, the coil bears against the inside portion of the radial sleeve and forms the surface from which a fuel pellet biasing spring maintains fuel pellets within the unsealed fuel rod.

Abstract: A method of ultrasonic inspection of a reactor nozzle involves positioning emitter and receiver transducers on the exterior vessel wall near the nozzle. The emitter transducer is positioned and oriented so that it generates both primary longitudinal and transverse beams. The primary longitudinal beam is directed at the inner radius of the nozzle. The transverse beam is directed toward the interior vessel wall at an angle of about 30.degree. to the normal. Most of the energy of the transverse beam is converted to a secondary longitudinal beam also directed toward the inner radius of the nozzle. The receiver transducer is positioned on the exterior vessel wall about 4" from the emitter transducer so as to be able to detect reflections of both the primary and second longitudinal beams from any potential defect in the nozzle volume adjacent the inner radius.

Abstract: A water rod is disclosed in combination with a fuel bundle for a boiling water nuclear reactor in which water is introduced to the water rod directly from the high pressure lower plenum below the reactor core. This introduced water circulates upwardly and centrally through the water rod to the top of the water rod. Thereafter, the water flows peripherally downward adjacent the exterior of the water rod. The introduction of water to the water rod directly from the high pressure water plenum below the reactor core provides sufficient pressure to maintain water flow through the water rod and to prevent flashing of the water passing through the circuitous path of the water rod to steam. Thereafter, the water is discharged at the bottom of the fuel bundle with water entering the steam generation path through the lower tie plate so that the discharged water participates in the steam generating flow path within the fuel bundle.

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 a boiling-water nuclear reactor, a core-control assembly comprises a control rod, a fuel support, a control-rod guide tube, a control-rod drive, and a control-rod-drive housing. The fuel support is welded to the control-rod guide tube. To remove the control-rod drive, the reactor vessel can be opened and the adjacent fuel bundles removed from the fuel support. Then the control-rod can be rotated after clearing the fuel support. The control rod is then rotated to decouple its bayonet connection to the control-rod drive. The control rod can then be lifted out of the reactor. This arrangement allows a control rod to be replaced without handling of the fuel support. In addition, the fuel support can be more securely installed since it does not need to be removed.

Abstract: A reactor core removable fuel assembly includes upper and lower tie plates having pluralities of fuel rods and hollow control rods extending therebetween. The lower tie plate includes a lower manifold therein joined in flow communication with a reservoir containing a neutron absorbing control liquid, with the reservoir being removable from the reactor core together with the fuel assembly. The control liquid is selectively pumped from the reservoir through the lower manifold and into the control rods for selectively varying the level of the control liquid therein for controlling reactivity.