Abstract: A method for separating isotopes in which a selected isotope is first ionized in a partially bounded region and then driven toward the boundary by space charge electric fields. Radial electric fields, which accelerate movement of the charged particles towards the walls of the boundary, are generated by charge separation associated with ambipolar diffusion of the particles in the plasma column. Selective photoexcitation leads to the preferential ionization of the isotopic component to be separated from the gas mixture. The resulting altered gas mixture component concentrations in the central region and periphery of the bounded area flow from the system through different output channels.

Abstract: A transducer for identifying and quantitatively measuring the presence and location of ferromagnetic material, which is specifically suitable for remotely mapping ferromagnetic deposits on pressurized water reactor steam generator tubing. The transducer employs a first source of a magnetic field which is positionable in magnetic communication with and is mounted to be movable over the surface area of the workpiece. Perturbations produced in the magnetic field as a result of ferromagnetic discontinuities associated with the workpiece are sensed by a Hall element fixedly positioned with respect to the source in magnetic communication with the workpiece. Means are provided for altering the magnetic field of the source in communication with the Hall element to substantially null the output of the Hall element in the absence of magnetic material within or on the workpiece within proximity of the Hall element.

Abstract: Apparatus employing ultrasonic energy for detecting and measuring the quantity of gas bubbles present in liquids being transported through pipes. An ultrasonic transducer is positioned along the longitudinal axis of a fluid duct, oriented to transmit acoustic energy radially of the duct around the circumference of the enclosure walls. The back-reflected energy is received centrally of the duct and interpreted as a measure of gas entrainment.One specific embodiment employs a conical reflector to direct the transmitted acoustic energy radially of the duct and redirect the reflected energy back to the transducer for reception. A modified embodiment employs a cylindrical ultrasonic transducer for this purpose.

Abstract: Apparatus is disclosed for handling radioactive fuel assembly during transfer operations. The radioactive fuel assembly is drawn up into a shielding sleeve which substantially reduces the level of radioactivity immediately surrounding the sleeve thereby permitting direct acess by operating personnel. The lifting assembly which draws the fuel assembly up within the shielding sleeve is mounted to and forms an integral part of the handling apparatus. The shielding sleeve accompanies the fuel assembly during all of the transfer operations.

Abstract: A method and apparatus for establishing the axial flux distribution of a reactor core from monitored responses obtained exterior of the reactor. The monitored responses obtained exterior of the reactor. The monitored responses are obtained from at least three axially spaced flux responsive detectors that are positioned within proximity of the periphery of the reactor core. The detectors provide corresponding electrical outputs representative of the flux monitored. The axial height of the core is figuratively divided at a plurality of space coordinates sufficient to provide reconstruction in point representation of the relative flux shape along the core axis. The relative value of flux at each of the spaced coordinates is then established from a sum of the electrical outputs of the detectors, respectively, algebraically modified by a corresponding preestablished constant.

Abstract: A method for removing cesium 137, iodine 131 and tritium from a liquid sodium reactor coolant. Hydrogen is introduced into the liquid sodium causing sodium hydride to precipitate in a cold trap. The cesium iodine and tritium isotopes are removed from the liquid sodium by coprecipitating as impurities in the sodium hydride.

Abstract: A method and apparatus for sensitively monitoring flux deviations along a given core plane of a nuclear reactor as detected by a plurality of flux sensitive detectors positioned around the periphery of the core within the monitoring plane. The detector responses are averaged and the respective detector outputs exceeding the average are summed and compared to a preselected design setpoint. Sums of the detector outputs exceeding the setpoint are annunciated alerting the plant operator to take corrective action to avoid surpassing design limits.

Abstract: This invention provides a method of operating a nuclear reactor with the object of maintaining a substantially symmetric axial xenon distribution during normal power operation including load follow. Variations in the xenon distribution are controlled by maintaining a substantially symmetric axial power distribution. Procedures are described for maintaining the axial offset value of the core, as an indicia of the axial power distribution, substantially equal to a target value, which is modified periodically to account for core burnup. In one embodiment a neutron absorbing element within the core coolant, or moderator, is employed to assist control of reactivity changes associated with changes in power with the full length control rods mainly employed to adjust variations in the axial power distribution, while the part length rods remain completely withdrawn from the fuel region of the core.

Abstract: A DC pulse generator, specifically suitable for application as a cardiac pacemaker having a substantially constant energy output which is independent of the output load. The output pulse is derived from a capacitive reactance which is partially discharged to a preselected reference level. The cyclic rate of discharge is maintained substantially constant, and accordingly, the pulse width is varied to assure a constant energy output to the load. The capacitive reactance is charged in between output pulse periods from a matched impedance radioisotope thermoelectric source through a constant current inverter, step-up transformer, voltage doubler, inverter network. The oscillator controlling cyclic discharge of the capacitance through the load and the inverter, which is arranged in a push-pull configuration, is designed to be self-starting to avoid stall conditions during operation. Furthermore, the discharge rate is substantially independent of the DC level and provides a negative rectangular output pulse.

Abstract: A bearing and seal structure for nuclear reactors utilizing rotating plugs above the nuclear reactor vessel. The structure permits lubrication of bearings and seals of the rotating plugs without risk of the lubricant draining into the reactor vessel below. The structure permits lubrication by utilizing a rotating outer race bearing.

Abstract: Apparatus for measuring displacements of core components of a liquid metal fast breeder reactor by means of an eddy current probe. The active portion of the probe is located within a dry thimble which is supported on a stationary portion of the reactor core support structure. Split rings of metal, having a resistivity significantly different than sodium, are fixedly mounted on the core component to be monitored. The split rings are slidably positioned around, concentric with the probe and symmetrically situated along the axis of the probe so that motion of the ring along the axis of the probe produces a proportional change in the probes electrical output.

Abstract: Methods and apparatus for identifying the source location of acoustic emissions generated within an acoustically conductive medium. A plurality of acoustic receivers are communicably coupled to the surface of the medium at a corresponding number of spaced locations. The differences in the reception time of the respective sensors in response to a given acoustic event are measured among various sensor combinations prescribed by the monitoring mode employed. Acoustic reception response encountered subsequent to the reception by a predetermined number of the prescribed sensor combinations are inhibited from being communicated to the processing circuitry, while the time measurements obtained from the prescribed sensor combinations are translated into a position measurement representative of the location on the surface most proximate the source of the emission. The apparatus is programmable to function in six separate and five distinct operating modes employing either two, three or four sensory locations.

Abstract: A nuclear core arrangement for admitting reactor coolant into nuclear reactor fuel assemblies. Inlet nozzles having main and alternate inlets are attached to the fuel assemblies. Each of the nozzle inlets receive reactor coolant from a separate flow plenum. The flow plenums are arranged in parallel and are separated by a perforated sealing member. Should the main inlet to the fuel assembly become clogged by debris, the alternate inlet supplies the fuel assembly with reactor coolant.

Abstract: A non-destructive acoustic method for measuring gas pressure in a hermetically sealed enclosure. In accordance with the method, an acoustic signal is generated and transmitted through the gas medium within the enclosure. The acoustic impedance mismatch between the enclosure and the gas medium is dependent upon the pressure of the gas and correspondingly affects the transmissivity of the acoustic signal. The signal is received after traversing a given travel path through the gas and converted into a corresponding electrical output calibrated against a standard to provide a direct measure of the pressure of the gas within the enclosure. In the preferred arrangement, the enclosure is acoustically damped to substantially dissipate acoustic energy traveling within the enclosure walls.

Abstract: Methods and apparatus for identifying the source location of acoustic emissions generated within or on an acoustically conductive medium segregated into a plurality of quadrilateral monitoring zones. A plurality of acoustic receivers are communicably coupled to the surface of the medium respectively at the zone corner locations. Each receiver is responsive to the reception of an acoustic emission to provide a corresponding electrical output. The electrical response of the respective receivers are coupled to corresponding counters in a manner to enable the counters to sequence through their respective counting states. The receiver outputs are monitored to identify the first zone exhibiting an acoustic reception at all four corners. Once such a zone has been identified, all counters are inhibited from sequencing and are locked into the last counting state cycled.

Abstract: An improved, self-powered, gamma compensated, neutron detector having two electrically conductive concentric cylindrical electrodes and a central rod emitter formed from a material which emits beta particles when bombarded by neutrons. The outer electrode and emitter are maintained at a common potential and the neutron representative current is furnished at the inner cylindrical electrode which serves as a collector. The two concentric cylindrical electrodes are designed to exhibit substantially equal electron emission induced by Compton scattering under neutron bombardment to supply the desired gamma compensation.

Abstract: A method for monitoring the displacement of an object having an acoustically reflective surface at least partially submerged in an acoustically conductive medium. The reflective surface is designed to have a stepped interface responsive to an incident acoustic pulse to provide separate discrete reflected pulses to a receiving transducer. The difference in the time of flight of the reflected acoustic signals corresponds to the known step height and the time of travel of the signals to the receiving transducer provides a measure of the displacement of the object. Accordingly, the reference step length enables simultaneous calibration of each displacement measurement.

Abstract: A system for providing a desired energizing current, according to a reference current signal, to a load or group of load elements. Three phase energizing current is rectified by a plurality of controlled switching devices such as thyristors, and apparatus is provided for varying the firing angle of the thyristors in accordance with the reference current signal to regulate the resulting output voltage therefrom and thereby regulate the energizing current through the load.

Abstract: A neutron flux radiation detector is provided that utilizes neutron radiation induced nonlinear acoustic behavior in water, with the resultant mixing of two ultrasonic signals in transit through the liquid, to provide a measure of ambient radiation levels. Nonlinear elastic properties are imparted to the water by the presence of microcavities which are formed when high-energy neutrons collide with the waters atomic nuclei.The detector employs an ultrasonic transmitting transducer which is driven simultaneously at two different frequencies. The acoustic output is transmitted through a container housing a pool of distilled water. Only when radiation is present will the acoustic signals in transit through the water undergo harmonic distortion and "mix", thereby generating sum and difference frequencies. These sum and difference frequencies are then sensed using a separate receiving transducer, and are identified as a measure of the ambient radiation level.

Abstract: An internally pressurized hermetically clad fuel element for a nuclear reactor having a sealed collapsible capsule within the fuel element plenum. The capsule is controllably collapsed in a buckling mode with increases in plenum pressure to maintain the fuel element pressure substantially constant throughout its operating life.