Abstract: The nuclear reactor shutdown system comprises a temperature sensitive device connected to a magnetic latch of a neutron absorbing mechanism. The temperature sensitive device is disposed in the neutron absorbing mechanism in such a manner that it is exposed to the reactor coolant so that when the reactor coolant temperature rises above a specific level, the temperature sensitive device will cause the magnetic latch to open and allow neutron absorbing material to enter the reactor core. The temperature sensitive device comprises temperature sensitive material which may be a temperature sensitive resistor sometimes referred to as a thermistor. The thermistor is a device wherein its resistivity significantly increases with increase in its temperature such that when its temperature has significantly increased, the current passing through this system substantially decreases.

Abstract: The tube plug comprises a shell having a tapered inner surface against which an externally tapered expander member moves by application of a pulling force. The motion of the expander member relative to the shell causes the shell to expand into contact with a heat exchange tube thereby plugging the tube. The expander member is formed from a hardened metal with tangentially blended leading radius and a self-locking trailing edge which provides for ease in expanding the shell while preventing inadvertent unlocking of the plug. The shell has a substantially uniform wall thickness throughout the portion of the shell which experiences expansion so that the force necessary to perform the expanding process does not increase beyond the strength limitations of the installation equipment as the expander member is moved through the shell.

Abstract: A grid for a nuclear reactor fuel assembly which includes two sets of interwoven straps which form square openings of egg-crate configuration. One set is placed on top the other with the openings in alignment to receive fuel rods. The vertically aligned square openings thus constitute single cells through which fuel rods are adapted to extend. The top edges of straps in the bottom grid are provided with narrow slots which extend in multiple rows diagonally across the grid when the straps are assembled. A spring, one for each row of diagonal slots, is threaded through the slots before the top grid is set in place. Each single cell contains two pairs of vertically spaced dimples on adjacent walls of the straps as in conventional construction. That portion of the spring, which extends through each cell, engages a side of the fuel rod in the cell and urges it into contact with the dimples, thus providing five points of support for each fuel rod which extends through the cells.

Abstract: A fuel cell and system for supply electrolyte, as well as fuel and an oxidant to a fuel cell stack having at least two fuel cells, each of the cells having a pair of spaced electrodes and a matrix sandwiched therebetween, fuel and oxidant paths associated with a bipolar plate separating each pair of adjacent fuel cells and an electrolyte fill path for adding electrolyte to the cells and wetting said matrices. Electrolyte is flowed through the fuel cell stack in a back and forth fashion in a path in each cell substantially parallel to one face of opposite faces of the bipolar plate exposed to one of the electrodes and the matrices to produce an overall head uniformly between cells due to frictional pressure drop in the path for each cell free of a large hydrostatic head to thereby avoid flooding of the electrodes.

Abstract: A fuel assembly in a nuclear reactor comprises a locking mechanism that is capable of locking the fuel assembly to the core plate of a nuclear reactor to prevent inadvertent movement of the fuel assembly. The locking mechanism comprises a ratchet mechanism that allows the fuel assembly to be easily locked to the core plate but prevents unlocking except when the ratchet is disengaged.

Abstract: A method of encapsulating radioactive waste including withdrawing radioactive liquid having a retardant therein from a source. The retardant may including borates, or other additives, which retard the setting of cements by preventing hydration at cement particles in the mix. The liquid is mixed with ordinary Portland cement and subjected to long term shear far in excess of that needed to form ordinary grout. The use of shear to overcome set retardation, and similarly, the deliberate regulation of acceleration of set in hydraulic cement pastes by the utilization of retardants plus shear produces a thixotropic paste with extreme moldability which will not bleed, and finally sets more rapidly than can be expected with normal mixing to form a very strong product.

Abstract: An improved control rod guide tube for use in a fuel assembly in a nuclear reactor. The guide tube extends the complete length of the fuel assembly and has its upper end fastened in a cylindrical housing by swaging the guide tube material into grooves formed in the housing walls. To eliminate wear on the guide tube inner walls caused by hydraulic induced vibratory forces on a control rod adapted to move therein, a thin-walled chrome plated sleeve is threaded into the top end of the guide thimble and extends downwardly a distance sufficient to be engaged by the control rod during reactor operation. The sleeve serves as a highly resistant wear surface between the control rod and walls on the guide tube in the fuel assembly.

Abstract: An arrangement for controlling the moderation of a nuclear reactor which includes multiple fuel assemblies each of which includes top and bottom nozzles with fuel rods and control rod guide thimbles located therebetween. Certain ones of said assemblies include at least one tube initially filled with a gas. One end of the tube rests on the lower nozzle upper surface while the upper end terminates at a point just below the lower plate in the upper nozzle. A spike immovably fixed in the lower plate of the upper nozzle is directed downwardly toward the end of the tube. As the tube expands or grows during operation in a reactor, and at a point where the criticality factor may proceed to less than one, the expanded tube will be pierced by the spike and thus permit the escape of gas from the tube which is then replaced by water coolant circulating through the reactor.

Abstract: A steam cycle for a nuclear power plant having two optional modes of operation. A once-through mode of operation uses direct feed of coolant water to an evaporator avoiding excessive chemical concentration buildup.A recirculation mode of operation uses a recirculation loop to direct a portion of flow from the evaporator back through the evaporator to effectively increase evaporator flow.

Abstract: The plug removal apparatus comprises a ram mounted in a rod both of which are mounted in an activating cylinder. The rod is capable of being scrwed into the plug such that when the cylinder is activated, the cylinder causes the ram to push the expander relative to the plug while the rod holds the plug thereby relieving the pressure on the plug. The activating cylinder may then be activated so as to extract the plug from the tube using short strokes. The apparatus is capable of being used manually or remotely so as to be able to remove plugs from heat exchangers and nuclear steam generators.

Abstract: A high temperature tube and shell vertically positioned heat exchanger including a plurality of tube sheets dividing the interior of the shell into three consecutive chambers. Ceramic tubes are vertically hung from hemispherical seats in an upper tube sheet and extend downwardly through loose fitting porous inserts which line perforations in the lower tube sheets. A hot fluid flows from the bottom chamber upwardly through the ceramic tubes, a cool fluid flows through the upper chamber across the tubes, and a third fluid is injected into the intermediate chamber at a pressure higher than that of the fluid mediums in the upper and lower chambers. The third, high pressure fluid flows through the porous inserts and into the other chambers forming a dynamic seal which also allows unrestricted axial motion of the tubes and limited laterial motion of the bottom of the tubes.

Abstract: The liquid metal pump comprises floating seal rings and attachment of the pump diffuser to the pump bowl for isolating structural deflections from the pump shaft bearings. The seal rings also eliminate precision machining on large assemblies by eliminating the need for a close tolerance fit between the mounting surfaces of the pump and the seals. The liquid metal pump also comprises a shaft support structure that is isolated from the pump housing for better preservation of alignment of shaft bearings. The shaft support structure also allows for complete removal of pump internals for inspection and repair.

Abstract: Wind turbine generator systems incorporating a multi-speed pole amplitude modulated type dynamo electric machine allowing efficient operation at consecutive speeds in a ratio preferably less than 2:1. A current limiting reactor, preferably including an inductance coil, and an over-running clutch, are utilized in conjunction with any multi-speed generation system to alleviate impact on a utility grid during switching among operational speeds.

Abstract: Arrangements of stacks of fuel cells and ducts, for fuel cells operating with separate fuel, oxidant and coolant streams. An even number of stacks are arranged generally end-to-end in a loop. Ducts located at the juncture of consecutive stacks of the loop feed oxidant or fuel to or from the two consecutive stacks, each individual duct communicating with two stacks. A coolant fluid flows from outside the loop, into and through cooling channels of the stack, and is discharged into an enclosure duct formed within the loop by the stacks and seals at the junctures at the stacks.

Abstract: This invention provides a loading mechanism for directing nuclear fuel pellets from one elevation to a lower container via gravity. The mechanism includes a loading chute into which the pellets are deposited and a vertically movable platform therebelow supporting a replaceable container to receive the pellets from the chute. The chute includes a plurality of generally oppositely downwardly angled resiliently covered plates defining a zig-zag path through the chute to limit the accumulation of momentum to the pellets, and the platform is spring-biased against the accumulated weight of the pellets and container so as to be continuously lowered as the weight thereof increases as the pellets are deposited in the container.

Abstract: A design of fuel assembly control rod guide thimble which includes insets or indentations which project inwardly from the upper end of the guide thimble and extend longitudinally of the thimble for about the same distance traversed by a control rod movable therein. These preferentially formed discrete indented areas or insets within the guide thimble provide for controlled localized control rod to guide thimble wear. The insets minimize wear at the control rod-guide thimble interface by lowering the normal load and encouraging the control rod into a line contact wearing mode. Additional insets may be remotely installed after irradiation if desired.

Abstract: The decontamination apparatus comprises a rotatable hone capable of being inserted into a heat exchange tube of a steam generator for removing contamination from the inside of the heat exchange tubes. The apparatus also comprises means for advancing and retracting the hone and means for removing contamination from the apparatus as the apparatus is withdrawn from the steam generator.

Abstract: A method and arrangement for utilizing mixed oxide fuel in the core of a nuclear reactor controlled by rectilinearly movable control rod elements which decreases the maximum single control rod element worth in the core. Fuel elements containing the mixed oxide fuel are positioned at discrete core locations, particularly at those locations receiving high worth control rod elements, thereby decreasing the worth of those control elements.

Abstract: A fuel cell arrangement having cooling fluid flow passages which vary in surface area from the inlet to the outlet of the passages. A smaller surface area is provided at the passage inlet, which increases toward the passage outlet, so as to provide more uniform cooling of the entire fuel cell. The cooling passages can also be spaced from one another in an uneven fashion.

Abstract: A reconstitutable fuel assembly for a nuclear reactor which includes a mechanical, rather than metallurgical, arrangement for connecting control rod guide thimbles to the top and bottom nozzles of a fuel assembly. Multiple sleeves enclosing control rod guide thimbles interconnect the top nozzle to the fuel assembly upper grid. Each sleeve is secured to the top nozzle by retaining rings disposed on opposite sides of the nozzle. Similar sleeves enclose the lower end of control rod guide thimbles and interconnect the bottom nozzle with the lowermost grid on the assembly. An end plug fitted in the bottom end of each sleeve extends through the bottom nozzle and is secured thereto by a retaining ring. Should it be necessary to remove a fuel rod from the assembly, the retaining rings in either the top or bottom nozzles may be removed to release the nozzle from the control rod guide thimbles and thus expose either the top or bottom ends of the fuel rods to fuel rod removing mechanisms.