Abstract: An apparatus and method for monitoring corrosion to members within the core of a nuclear reactor, particularly fuel rod cladding. A sensor means is submerged inside the core of a nuclear reactor near the member of fuel rods. The sensor means is comprised of a generally cylindrical section having an outer surface that is subject to corrosion and radiation, and has a cross-sectional area A.sub.1. The sensor means additionally has a reference section subjected to radiation but not to corrosion, and having a cross-sectional area A.sub.2. At least one pair of first probes, separated by a length L.sub.1, is placed in electrical contact with the cylindrical section. At least one pair of second probes separated by a length L.sub.2, is placed in electrical contact with the reference section. A current is passed throughout the sensor means to produce a potential gradient in the cylindrical section and reference section.

Abstract: A drive for positioning a control rod in a nuclear reactor core is disclosed. The drive includes a housing having a piston disposed therein, with a piston rod extending from the piston and through the housing for being joinable to the control rod. A driving fluid is provided into the housing for exerting a pressure force against the piston for moving the piston and the control rod. The output requirements for the driving fluid are varied in response to the position of the piston for selectively controlling intermediate positions of the piston.

Abstract: A boiling water nuclear water plant includes a reactor core isolation cooling (RCIC) system in which a turbine used to pump feedwater to the reactor also drives a generator. The generator is used to drive RCIC components, such as a room cooler and control electronics, during station blackout.

Abstract: A forced-circulation boiling-water reactor includes bypass check valves between a downcomer and a core inlet plenum. When the recirculation pumps are operating at full capacity, there is a maximum pressure differential from the downcomer to the core inlet plenum. This pressure differential keeps the valves closed so that recirculating fluid is constrained to flow through the pumps. When the pumps are not operating, a driving water head in the downcomer forces the valves open, augmenting the flow cross section between the downcomer and the core inlet plenum, enhancing natural circulation. The enhanced natural circulation provides greater core stability during pump shutdown. The valves are selected or adjusted so that they open when the pressure differential falls through a predetermined range to augment diminished pumping capacity with a higher natural circulation flow rate.

Abstract: A thimble tube for use in a guide the in a nuclear reactor. The thimble tube is an elongated hollow tube having one end closed. The portion of the tube that extends into the reactor is formed from a plurality of sections attached to each other to form the tube in an alternating fashion along the width and length of the tube. The sections are formed from materials having different coefficients of thermal expansion. This causes the thimble tube to warp into supporting contact with the interior of the guide tube at normal reactor operating temperature.

Abstract: The invention relates to a sealing sleeve for sealing a leak in, for example, a pipe, a pipe socket or the like in a nuclear reactor. The sleeve comprises a bellows-like mid-portion (1) with annular ends, at least these or part of these (2) being made of a memory metal with a suitable transition temperature. At a temperature above the transition temperature, that part of these annular ends which consists of memory metal has been given an inner diameter suitable for achieving sealing around the relevant pipe section on each side of the leak. The mentioned part of the ends has thereafter, at a temperature below the transition temperature, been deformed into a diameter which permits the sleeve to be freely fitted onto the pipe. In fitted position, the sleeve is then heated to above the transition temperature, the memory metal then striving to recover its previous shape and shrinks the sleeve so as to obtain sealing.

Abstract: A method is disclosed for denitrification of nitrates and nitrates present in aqueous waste streams. The method comprises the steps of (1) identifying the concentration nitrates and nitrites present in a waste stream, (2) causing formate to be present in the waste stream, (3) heating the mixture to a predetermined reaction temperature from about 200.degree. C. to about 600.degree. C., and (4) holding the mixture and accumulating products at heated and pressurized conditions for a residence time, thereby resulting in nitrogen and carbon dioxide gas, and hydroxides, and reducing the level of nitrates and nitrites to below drinking water standards.

Abstract: A nuclear reactor coolant pump has a casing defining an inlet nozzle for receiving a reactor coolant fluid, an outlet nozzle for discharging the fluid, and a passage interconnecting the inlet and outlet nozzles through which the fluid can flow in a main stream from the inlet nozzle to outlet nozzle. The pump also has a central rotor with one end disposed adjacent the annular passage of the casing and opposite bearings rotatably mounting the rotor to the casing. A motor is disposed about the rotor and between the bearings and is operable for rotatably driving the central rotor. An impeller is mounted to the one end of the rotor in communication with the annular passage and the flow of fluid therethrough. The impeller rotates with the rotor to create a lower pressure at the inlet nozzle than at the outlet nozzle for drawing the reactor coolant fluid into the casing through the inlet nozzle and discharging the fluid from the casing through the outlet nozzle.

Abstract: An improved apparatus and method for ultrasonic inspection of materials through barriers such as gaps in manufactured parts is disclosed. The improvement herein is directed to enabling such ultrasonic testing to bridge ambient gaps such as intentionally formed gaps in composite structures having a first structure for originally receiving and transmitting sound separated by the gap from another structure to be inspected. Preferably, the gap is flooded with a gas having a predictable and optimum speed of sound relative to the material of the first and second structures. Sound is propagated to the first structure in a wave packet that is transmitted through the couplant fluid. The sound is generated in a wave packet having a spatial width at least twice the dimension of the gap to be bridged. The wave packet has a contained frequency having a wavelength (relative to the speed of sound of the gas flooding the gap) to create a constructively interfering standing wave node within the gap.

Abstract: In an apparatus including a fluid circulation unit for allowing a fluid in a container to be circulated along a passage in the container, a flow rate measuring apparatus includes a rotational speed transducer for detecting the rotational speed of a motor for driving the fluid circulation unit and a pipe network model calculator for receiving a rotational speed signal from the rotational speed transducer. The model calculator has an initially programmed pipe network model corresponding to flows in the container and calculates the flow rate at a corresponding location of the model with the rotational speed of the circulation unit replaced by constants of the model and hence calculates a flow rate of the fluid at that location in a real passage.

Abstract: A method is described for the chemical reduction of plutonium oxides to plutonium metal by the use of pure lithium metal. Lithium metal is used to reduce plutonium oxide to alpha plutonium metal (alpha-Pu). The lithium oxide by-product is reclaimed by sublimation and converted to the chloride salt, and after electrolysis, is removed as lithium metal. Zinc may be used as a solvent metal to improve thermodynamics of the reduction reaction at lower temperatures. Lithium metal reduction enables plutonium oxide reduction without the production of huge quantities of CaO--CaCl.sub.2 residues normally produced in conventional direct oxide reduction processes.

Abstract: A fuel assembly for a boiling water reactor includes an elongated fuel assembly case, mutually parallel fuel rods having longitudinal axes and being disposed in the case, and longitudinally extending inner walls having lateral surfaces facing toward the fuel rods. At least some of the lateral surfaces have grooves formed therein extending perpendicular to the longitudinal axes of the fuel rods. A boiling water reactor includes a boiling water circuit having a pressure vessel and a steam turbine. A plurality of the fuel assemblies are disposed mutually parallel in the pressure vessel. The fuel rods are bathed by boiling water flowing around them in the longitudinal direction of the fuel rods.

Abstract: The assembly (1) is immersed in the water of a pool and placed in vertical position. Detection of the rods (6) of the assembly exhibiting cracks giving rise to leakage is ensured by transmission of ultrasonic waves along the length of each of the rods (6) and by measuring the attenuation of the ultrasonic waves due to the presence of water inside the rods (6) whose cladding is cracked. The ultrasonic waves are picked up after propagation on the cladding of the rods (6) of the assembly along their length, below the lower end fitting (5) in place on the assembly (1). The detecting device comprises an ultrasonic transducer (11) capable of transmitting ultrasonic waves along the length of the rod from its upper part, and a receiver probe (16) for the ultrasonic waves, placed under the lower end fitting (5).

Abstract: An apparatus for refurbishing the ends of control rod drive (CRD) penetrations used in nuclear boiling water reactor systems where the rods are disposed in a grid of rows and columns with a known predetermined spacing therebetween. The apparatus is rapidly positioned for support on a pair of CRDs adjacent to a CRD to be refurbished, coaxially aligning the end mill with the CRD to be refurbished. The end mill is then brought into contact with the CRD to be refurbished. After the refurbishment process, the apparatus is rapidly removed and ready to be positioned on another pair of CRDs adjacent to another CRD to be refubished.

Abstract: A reactor core includes upper and lower matrices of fuel bundles. Fuel rods in the upper matrix have their plenums oriented upward, while fuel rods in the lower matrix have their plenums oriented downward. Refueling involves removal of a first bundle in the upper matrix, removal and retirement of the bundle in the lower matrix directly below the original position of the first bundle, inversion and installation of the first bundle in the lower matrix, and installlation of a new bundle in the upper matrix. The new bundle is installed plenum-side up. The bi-level core provides greater flexibility in repositioning fuel bundles for longer burnups and lower high-level waste. In particular, problems with axial spectral variations in neutron flux can be compensated using the disclosed core arrangement and refueling procedure.

Abstract: The present invention relates to a method of cementing a radioactive waste and a cemented body thereof which are less liable to bring about radioactivity leakage for a long period of time and suitable for disposal of cemented bodies of radioactive wastes in the land.The radioactivity leakage from a cemented body of a radioactive waste occurs due to the presence of the voids within the cemented body, and these voids are formed during hardening of the cemented body or by leaching of a soluble component from the cemented body during immersion in water.In the present invention, in order to minimize the amount of radioactivity leakage, the fraction of fine voids (1 .mu.m or less) is limited to 20% by volume or less. In order to attain such a void fraction, operating conditions, such as water to cement ratio, hardening time of a mixture of a solidifying material with a waste, and addition of an organic polymer, are properly determined.Further, in order to prevent formation of a soluble component, i.e., Ca(OH).sub.

Abstract: An electromagnet for a nuclear reactor shutdown system, which comprises upper and lower cores disposed in an axially symmetrical arrangement and capable of latching with and delatching from each other. When an ambient temperature increases, the upper and lower iron cores are delatched from each other and a control rod connected to the lower iron core falls down into a reactor core. The lower iron core is provided with a plurality of slits to form a plurality of fins therebetween. A temperature sensitive magnetic material (TSMM) is disposed in the outer circumferential lower corner portion of the lower iron core. An interface between the TSMM and an iron core material takes the form of a side surface of a cone whose central axis is coincident with the symmetry axis and whose apex angle lies in the range of 60.degree. to 120.degree..

Abstract: The present invention relates to a Cu-based sintered alloy which has a composition containing: Zn: 10-40%; Al: 0.3%-6% oxygen: 0.03-1%; any one selected, as an additional element from the group including at least one of Fe, Ni and Co: 0.1-5%, Mn: 0.1-5%, Si: 0.1-3%, and at least one of W and Mo: 0.1-3%; and the remainder including Cu and inevitable impurities. The alloy is superior in wear resistance particularly in air at temperatures ranging from the ordinary temperature to 400.degree. C., has high strength and high toughness, and further excels in the uniform temporal change characteristics with associated members, as evaluated by its friction coefficient. The invention relates also to parts for automotive equipment made of this Cu-base sintered alloy, such as synchronizer rings for transmission, valveguides for engines, bearings for turbo-chargers and so forth.

Abstract: An apparatus and method to facilitate the in situ detection of small leaks in fluid-filled, capacitive type pressure transducers by remotely and non-intrusively inducing a brief time varying transient signal, and then analyzing the frequency response of the transducer to such excitation in order to detect the presence and effects of a fluid leak. The adverse effect of this induced transient signal on the process control circuitry is insignificant, while providing for an accurate and sensitive method for detecting the extent of fluid loss in the transducer when evaluated according to the present invention. As a consequence of such transducer evaluation techniques, frequency responsive characteristics of such devices may be recorded and self-correlated over long periods of time.

Abstract: An improved method of disposing of radioactive or hazardous liquids comprises placing the liquids in a container and adding a sodium montmorillonite over intervals until the composition is substantially solid in the container.