Abstract: An apparatus for the volume reduction of radioactive liquid waste solutions such as evaporator waste bottoms containing boric acid or sodium sulfate and trace quantities of radioactivity through a vacuum evaporative cooling crystallization process or an evaporative crystallization process. A crystallization unit has an internal baffle which separates the center portion of the unit into a quiescent zone where crystallization can be effected and an inner chamber into which the liquid waste is tangentially introduced. The waste is circulated from the bottom of the crystallization unit through a heat exchanger which adjusts the temperature of the liquid waste and maintains the temperature within a predetermined range. The vacuum draws off a portion of the solvent in the solution. Upon the crystallization of the liquid waste solution to a degree which renders a solid-liquid slurry, the slurry is removed from the apparatus for further treatment.

Abstract: Excessive swing of the feedwater in power supply apparatus on the occurrence of a transient is suppressed by injecting an anticipatory compensating signal into the control for the feedwater. Typical overshoot occurs on removal of a large part of the load, the steam flow is reduced so that the conventional control system reduces the flow of feedwater. At the same time there is a reduction of feedwater level in the steam generator because of the collapse of the bubbles under increased steam pressure. By the time the control responds to the drop in level, the apparatus has begun to stabilize so that there is overshoot. The anticipatory signal is derived from the boiling power which is a function of the nuclear power developed, the enthalpy of saturated water and the enthalpy of the feedwater injected into the steam generator. From the boiling power and the increment in steam pressure resulting from the transient are anticipatory increment of feedwater flow is derived.

Abstract: A steam generator tubesheet is serviced by end effectors mounted on a slew table cantilevered from a carriage slidable along an arm rotatable in a plane parallel to the tubesheet. In servicing a selected hole in the tubesheet, the rotatable arm and the carriage arm are driven to positions which allow the cantilevered slew table to be slewed to a predetermined angle associated with the selected hole. The arm and carriage are then driven to positions which place the end effector under the selected hole taking into account the offset of the slew table. Alternatively, a determination is first made whether the arm and carriage can be positioned within preset limits to place the end effector under the selected hole using the existing slew angle. If so, the existing slewed angle is used but, if not, the table is slewed as mentioned above.

Abstract: A breeder reactor fuel element having a tandem arrangement of fissile and fertile fuel with a getter for fission product cesium disposed between the fissile and fertile sections. The getter is effective at reactor operating temperatures to isolate the cesium generated by the fissile material from reacting with the fertile fuel section.

Abstract: Echo ranging flaw detecting, characterizing and studying apparatus in which the work is scanned simultaneously by acoustic energy focused at a point from an acoustic-lens transducer and by acoustic energy focused along a line along which it is propagated from a focused-arc transducer. The acoustical echos from the lens transducer are combined with an electrical analog of an acoustical reference wave to produce an acoustical interference pattern which is reconstructed into a holographic display or hologram by a laser beam. The echos from the focused-arc transducer produce a cathode-ray tube display or are stored in a memory.

Abstract: In detecting, characterizing or studying flaws in work whose surface is irregular by acoustic imaging in which a holographic pattern is produced the irregular surface is scanned by acoustic energy focussed on or near the irregular surface and the reception of the acoustic energy resulting from echoes from flaws is controlled for each scanned elemental area so as to reduce to a negligible magnitude the effects or variations in the acoustical path caused by the irregularties at different elemental areas in accordance with the irregularity at that area. The control may be effected by filling in the depressions in the irregular surface with an acoustic energy absorbing material such as butyl rubber or with a material, such as wax, which is not wetted by the liquid through which the acoustic energy is propagated to the surface.

Abstract: This invention provides a method of operating a nuclear reactor having a negative reactivity moderator temperature coefficient with the object of maintaining a uniform and symmetric Xenon distribution above and below substantially the center of the core over a substantial axial length of the core during normal reactor operation including load follow. In one embodiment variations in the Xenon distribution are controlled by maintaining a substantially symmetric axial power distribution. The axial offset, which is employed as an indication of the axial power distribution, is maintained substantially equal to a target value, which is modified periodically to account for core burnup.

Abstract: A condenser arrangement having a load bearing member hermetically coupled to the condenser's condensation chamber. Load transfer means are adapted to transfer the condenser vacuum load acting on the load bearing member to the turbine or turbine support in a manner to balance the condenser vacuum load acting on the turbine through the turbine exhaust. In the preferred arrangement means are provided to minimize contributions from the condensate to forces acting upon the load bearing member.

Abstract: Described is a movable work station apparatus including travelling-hoist supported tools and a vertically and rotarywise movable frame-carried radiation-shielded enclosure, or gondola, for working personnel involved in tube-bundle-replacement tasks performed within the shell of a steam generator in a nuclear plant. The enclosure, or gondola, is divided and accommodates four upright workers in mutually-facing pairs at opposite sides of a work-accommodating clearanceway observable and accessible from the gondola interior via lead glass windows and hand holes.

Abstract: Method and apparatus for removing the tube bundle from a steam generator disposed in a nuclear steam power plant while preserving an environment seal between the inside of the generator and the containment vessel. The tube bundle severed from the tubesheet is withdrawn upwardly into a multi-section crane including metal cask placed over an opened upper end of the steam generator shell. Removal of the bundle-containing cask is effectuated by the plant's radius crane and the cask lowered onto a metal cover plate made secure to the bottom of the cask. By a series of manipulations by the cask and radius cranes and use of tube and wrapper cutting equipment, length sections of the tube bundle and its wrapper can be contained in respective sequentially-separated top-and-bottom covered cask length sections for removal from the containment vessel.

Abstract: A method is described for electrically converting an analog signal into a digital representation in a manner that maximizes noise rejection. The digital representation is formed from a preselected number of discrete points corresponding to sampled approximations of the analog signal. In establishing the magnitudes of the respective points, digital samples of the analog signal are taken at a predetermined number of discrete coordinates along the analog signal on either side of the respective discrete points. The predetermined number of coordinates are averaged and employed as corresponding approximations for the respective discrete points in the digital representative reproduction of the analog signal. The effects of harmonics of power line frequencies associated with processing electrical equipment are minimized by sampling the discrete coordinates for a particular point over an integral number of cycles of the power line frequency.

Abstract: A method for separating isotopes in which a selected isotope of a given molecule is first excited to enhance preferential dissociative electron attachment, which facilitates the separation of the desired isotope from its natural mixture. Molecules incorporating the particular isotope of interest are selectively excited to the proper vibrational and/or electronic state by narrow line radiation to enhance preferential dissociative electron attachment. The excited molecules are then exposed to low energy electrons which dissociatively attach to the excited molecules forming stable negative ion fragments. The negative ion or neutral fragments containing the desired isotopes are then separated from the remaining mixture resulting in an enrichment of the desired isotope.

Abstract: A nuclear reactor containment arrangement incorporating a permanent cavity to vessel seal in the form of a flexible quarter-circular annular steel gasket affixed to and extending between the reactor vessel seal plate and cavity wall. The seal functions to isolate the periphery of the vessel from a permanent water-tight compartment above the reactor vessel which is flooded during refueling operations to minimize the release of radiation upon exposure of the nuclear core. The seal is designed to accommodate both radial and axial expansion of the pressure vessel relative to the cavity wall occurring during reactor operation without breaking the water-tight integrity of the seal. The pressure vessel ventilation system is provided with an air exit duct at the reactor nozzle level to facilitate the circulation of air around the periphery of the vessel which would otherwise be restricted at the seal to vessel interface.

Abstract: A method for deriving, from a starting material including an element having a plurality of isotopes, derived material enriched in one isotope of the element. The starting material is deposited on a substrate at less than a critical submonatomic surface density, typically less than 10.sup.16 atoms per square centimeter. The deposit is then selectively irradiated by a laser (maser or electronic oscillator) beam with monochromatic coherent radiation resonant with the one isotope causing the material including the one isotope to escape from the substrate. The escaping enriched material is then collected. Where the element has two isotopes, one of which is to be collected, the deposit may be irradiated with radiation resonant with the other isotope and the residual material enriched in the one isotope may be evaporated from the substrate and collected.

Abstract: A nuclear core including a reflector assembly cooling arrangement utilizing a combination of forced and natural convection cooling. Forced convection cooling is achieved by using a low pressure gradient to drive coolant through the reflector assembly. Natural convection cooling of the reflector assembly is accomplished by using heat from the reflector assembly and cooling provided by core bypass coolant flow to circulate coolant by natural means through the reflector assembly.

Abstract: Apparatus for establishing a solid, very low permeable rock glass plug to seal access holes through rock to underground storage vaults. The apparatus is designed to supply a filler material having a constituency substantially matching that of the rock formation surrounding the access port to the vault, through a central feeder tube under pressure to the vault. Means are provided for heating the filler material and surrounding rock formation at the point where the filler material exits the feeder tube, to a temperature sufficient to melt both the rock formation and the filler material. The remaining portion of the feeder tube is cooled to preserve the surrounding rock formation spaced from the feeder orifice. The melt at the extremity of the feeder tube is forced through the orifice to a region below the tool by the force of the pressure feed. As the melt is forced below the tool, the tool is retracted until the access hole is completely sealed.

Abstract: A method of controlling a nuclear power generating station in the event of a malfunction of particular operating components which minimizes the number of hypothecated occurrences where tripping the reactor might become necessary. Upon identification of such a malfunction, preselected groups of control rods are fully inserted sequentially until a predetermined power level is approached. Additional control rods are then selectively inserted to quickly bring the reactor to a second given power level chosen to be compatible with safe operation of the system with the malfunctioning component. At the same time as the thermal power output of the reactor is being reduced, the turbine is operated at a rate consistent with the output of the reactor. Thus, in the event of a malfunction, the nuclear power generating system is operated in a turbine following reactor mode, with the reactor power rapidly reduced, in a controlled manner, to a safe level compatible with the type of malfunction experienced.

Abstract: A method for detecting and locating defective fuel elements in a liquid cooled nuclear reactor employing a sonic/ultrasonic dual test. In accordance with the invention acoustic transducers, sensitive to a broad range of frequencies ranging from the audio to ultrasonic range, are respectively coupled to the exposed top end plugs of the fuel elements of a nuclear reactor fuel assembly. The respective fuel assemblies are voided of coolant, raising the temperature of the individual elements to a point that will boil any liquid coolant present in a defective fuel tube. The audio output of each transducer is translated into a graphic display identifying the presence and location of defective fuel elements. At prescribed intervals passive acoustic monitoring is interrupted for a pulse-echo attenuation measurement of each element. The respective transducers are sequentially energized, communicating pulsed acoustic energy along the fuel element cladding.

Abstract: The feedwater of a nuclear reactor at low-power levels, particularly during start-up, is controlled by combining an error signal component dependent on the departure of the actual level in the steam generator from a preset level and a component dependent upon the nuclear power delivered by the reactor. The nuclear-power change is the earliest reaction to the command to change the load level or to start up so that the nuclear-power component is a feedforwarded component. The invention prevents the system from "chugging." It also avails automatic control of the feedwater at low loading heretofore not feasible.

Abstract: A method and apparatus for preheating filler material to a temperature approaching its melting point prior to deposit within a weld zone. The weld zone and deposited filler material are then heated sufficiently to form an integral weldment. The power imparted to preheat the filler material is automatically, programmably, controlled as a predetermined function of the filler material deposition rate to obtain smooth melting of the filler material within the weld zone at any given filler material feed speed.In an application to welding an extended seam along a workpiece wherein the weld zone is moved along the seam, the power employed to heat the weld zone and the filler material feed speed are additionally controlled as a function of the speed of movement of the weld zone along the seam.