Abstract: To measure the gaps between fuel rods in a fuel assembly, a feeler gauge is provided with a pair of resilient arms having elongated electrical resistance strips carried by their confronting surfaces and extending from terminations adjacent the free ends of the arms through a contact point of electrical inter-engagement. The strip terminations are wired into a metering circuit including a current source and an ammeter. When the arm free ends are positioned in a rod gap, the position of the contact point relative to the strip terminations determines the magnitude of resistance included in the metering circuit, and the meter registers the gap dimension.

Abstract: A rotary lock is disclosed for preventing rotation of a shaft, such as a shaft used in a control rod drive for a nuclear reactor. The lock includes a stationary housing for receiving the shaft, and an arm extending outwardly from the shaft. At least one pin is joined to the housing for circumferential restraint and is positionable in a withdrawn position away from the arm for allowing the arm to rotate with the shaft without obstruction from the pin. The pin is also positionable in a deployed position contacting the arm for preventing rotation of the arm and shaft. Means are provided for selectivity positioning the pin in the withdrawn and deployed positions.

Abstract: A method of passivating the surface of particulate uranium oxides is disclosed comprising a process of continuously contacting uranium oxide particles with an oxygen containing and cooling counter flowing gas stream. The treatment produces a protective surface which inhibits subsequent oxygen chemisorption of the particulate uranium oxides.

Abstract: A spring-and-spacer assembly for maintaining fuel rods in a upright preferred position in a fuel assembly of a nuclear reactor core is provided. The spring has a leg portion and two loop portions, one at each end of the leg. Each loop engages an ear formed in a ferrule of the spacer. Each loop contains a dimple which contacts an ear of the ferrule. The central leg portion has a dimple, or a projection, which contacts a fuel rod and biases the fuel rod against stops. The spring load is transmitted to the ferrule ears by the dimples in the spring loops. Preferably, the spring rotates about the dimple when flexed, contributing to spring flexibility. The high spring flexibility permits use of the spring in connection with small rod-to-rod spacing fuel assemblies. This construction permits providing a low-mass, low-surface area spring, in turn providing for low neutron absorption and low flow obstruction.

Abstract: A process for controlling the oxidation reaction of oxides of uranium and fixing the ratio of oxygen to uranium in uranium oxide compounds by means of a passification process, and the stabilized uranium oxide compounds produced therefrom. The method is especially useful in the production of uranium oxide fuel for nuclear reactors.

Abstract: The present invention is directed to a venturi arrangement for use in measuring the flow rate of a fluid passed through a pipe bearing a venturi wherein the drawbacks associated with prior configurations have been ameliorated. The novel venturi arrangement comprises a pipe having a diameter, D, supplied in two sections, an upstream section and a downstream section, each of which preferably is flanged. Each of these pipe sections is fitted with a pair of pressure taps. A venturi comprising an annulus of diameter, D, has edges which are welded to said pipe sections to form an integral, fluid-conveying unit. A curvilinear conveying inlet section is integrally formed with the annulus. A throat section is integrally formed with the curvilinear conveying inlet section and contains a pair of pressure take-off apertures, each of which is connected by a flexible line to the downstream pipe pressure taps. Finally, a diverging diffuser section is integrally formed with the throat section.

Abstract: Nuclear fuel cladding tube end plug welds are ultrasonically scanned to develop data indicative of weld thickness, weld penetration, and the existence and size of any included feature, such as pores. A computer analyzes the data to determine critical weld characteristics which are then tested against established quality assurance standards to see if the end plug weld is acceptable, all on an automated production line basis.

Abstract: In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, an apparatus and method for the submerged welding repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. The apparatus registers to a hole in the core plate and its corresponding guide pin. A mating fixture on the depending extremity of the shaft of the apparatus precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand. For the welding repair process herein, a welding cylinder apparatus fits over the depending end of the shaft of the alignment device.

Abstract: The reference electrode probe of the present invention utilizes a metal/metal oxide/ZrO.sub.2 electrode sensor. Metal/metal oxide couples suitable include copper/copper oxide, tin/tin oxide, bismuth/bismuth oxide, and iron/iron oxide. The zirconia tube has a closed end and an open end. The closed end contains the metal/metal oxide powder and is retained therein by mineral insulation packing. A first annular metal sleeve is formed of metal exhibiting a coefficient of thermal expansion compatible with the zirconia tube and has a distal open end in sealing engagement with the open end of said zirconia tube. The first annular metal sleeve also has a proximal open end. An insulated first electrical conductor having a distal end in electrical connection with the metal/metal oxide powder extends through the mineral insulation packing and into the first annular sleeve. The first conductor also has a proximal end that terminates near the proximal end of the first annular sleeve.

Abstract: A liquid metal cooled nuclear reactor having a passive cooling system for removing residual heat resulting from fuel decay during reactor shutdown. The passive cooling system comprises a plurality of partitions surrounding the reactor vessel in spaced apart relation forming intermediate areas for circulating heat transferring fluid which remove and carry away heat from the reactor vessel.

Abstract: A fuel handling system for nuclear reactor plants comprising a camera containing underwater grapple means for transferring fuel units while submerged within a water containing reactor vessel.

Abstract: A fuel assembly transfer basket for a pool type, liquid metal cooled nuclear reactor having a side access loading and unloading port for receiving and relinquishing fuel assemblies during transfer.

Abstract: In a boiling water reactor having discrete bundles of fuel rods confined within channel enclosed fuel assemblies, an improved fuel design of bundles of fuel rods interior of the channels is disclosed. Specifically, partial length rods are utilized which extend from the bottom of the channel only part way to the top of the channel. These partial length rods are shortened with respect to the remaining rods and are symmetrically distributed throughout the fuel bundle with the preferred disposition being in the second row of the bundle of fuel rods from the channel wall. The symmetrical distribution of the partial length rods is at spaced apart locations one from another. The partial length rods extend from the bottom of the fuel bundle and terminate within the boiling region. during shutdown of the reactor, an improved cold shutdown margin is produced at the top of the fuel assembly due to the improved moderator-to-fuel ratio and reduction in plutonium formation at the upper portion of the bundle.

Abstract: To measure the dimensional characteristics of elongated flow channels for nuclear fuel rod assemblies at the manufacturing site, an upender is utilized to swing a flow channel from a horizontal loading orientation to an upright pre-measurement position and then to shift the flow channel laterally into a measurement position where it is engaged and held by reciprocatingly mounted upper and lower endplugs while its dimensional characteristics are acquired by a measurement carrige mounted for vertical scanning movement along the entire flow channel length.

Abstract: In the core of a boiling water nuclear reactor, local power range monitor strings typically including four vertically spaced monitoring sites are modified. Each monitoring site includes a conventional local power range detector in which fissionable material exposed to thermal neutron radiation produces fission fragments, ionizes a gas and produces a current between the anode and cathode. In the improvement herein, each conventional local power range detector is provided with one or two adjacent gamma thermometers; each gamma thermometer including an interior mass to be heated by gamma radiation, a thermocouple for measuring the heated mass and a reference thermocouple connected in series. Both the conventional local power range detector and the gamma thermometer(s) are all geometrically arranged in a string with individual connecting cables leading to external connectors, one for each detector and gamma thermometer.

Abstract: A metallic object is treated to produce tensile residual stress in a known localized area of the metallic object. A metallic object having at least one portion substantially free of tensile residual stress is provided, and a localized area adjacent to or a part of the tensile stress-free area is selected. The localized area is subjected to heating on one surface and cooling on the opposite surface. Upon cooling to ambient temperature, the known localized area has tensile residual stress. The localized area can have cracks formed therein by crack-promotion techniques, such as submersion in boiling magnesium chloride. The area can be tested by attaching electrodes and subjecting the area to a reversing direct current crack growth measurement procedure.

Abstract: An apparatus and process for the remote inspection for stress corrosion cracking of welded shut boiling water reactor shroud access cover plates is disclosed. The apparatus consists of a streamline housing having a top side with lugs for the attachment of lowering lines on either end of the housing. Medially of the streamline housing and projecting downwardly from the bottom of the streamline housing, there is provided a central rotating pedestal with a rubber base. The rotating pedestal and rubber base enable the entire housing to rest on and rotate relative to the pedestal and rubber base. A first motor interior of the housing rotates the housing at a bevel gear rigidly mounted to the central pedestal. A second motor rotates a threaded shaft driving a ball screw with an attached mount for an ultrasound transducer. The mount and transducer responsive to rotation of the ball screw traverse along the elongate dimension of the housing over an opening through the bottom of the housing.

Abstract: In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, an apparatus for the repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. The apparatus registers to a hole in the core plate and its corresponding guide pin. A mating fixture on the depending extremity of the shaft of the apparatus precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand.

Abstract: A spring-and-spacer assembly for maintaining fuel rods upright in a fuel assembly of a nuclear reactor core is provided. The spring is in the form of a continuous loop with first and second legs having mid-leg rod-contact regions. Bend regions are positioned on each side of each contact region extending toward the interior of the loop spring. In most positions, the spring is used to load two adjacent fuel rods. In configurations in which there is an unpaired fuel rod, a plate having a tab for contacting the spring is provided. The spring provides the desired force, such as about 2.5 pounds per fuel rod, in a small rod-to-rod spacing of less than about 0.14 inches.

Abstract: An improved upper tie plate is disclosed in a fuel bundle for a boiling water nuclear reactor. The tie plate resides in a fuel bundle including an upper tie plate, a lower tie plate, a matrix of sealed fuel rods supported therebetween, and a surrounding channel. Both the lower tie plate and the improved upper tie plate have two functions; they support the fuel rods in vertical upstanding relation between the tie plates and interior of the channel and permit the passage of moderating coolant through the channel from the bottom of the channel to the top of the channel. This moderating coolant enters through the lower tie plate in the liquid form, passes into the matrix of upstanding fuel rods where steam is generated and exits outwardly through the improved upper tie plate as a water steam mixture at the top of the fuel bundle.