Showing papers on "Liquid metal published in 1976"

Liquid metal cooling: A new solidification technique

Abstract: This paper describes a new and highly efficient directional solidification process using liquid metal as a coolant. A laboratory version of this process is reviewed in detail. The selection of a coolant is also discussed. Process thermal characteristics such as thermal gradient, growth rate and cooling rate are measured and compared with established directional solidification processing. Microstructural refinement of primary dendrites, secondary dendrite arms and MC carbides is demonstrated in the case of Ni-base super-alloys. Special advantages of the process, such as a lack of interdependence of growth rate and thermal gradient are discussed. Liquid Metal Cooling (LMC) offers a wide range of rate-gradient combinations and i therefore the most flexible directional solidification process discovered to date. The high levels of thermal gradient which are available make LMC a natural choice for the growth of eutectics. Alternatively, growth rates of dendritic materials can be substantially increased leading to significantly finer microstructures. Thus, LMC promises to be a highly useful process.

Dispersion strengthened ferritic alloy for use in liquid-metal fast breeder reactors (LMFBRS)

Abstract: A dispersion-strengthened ferritic alloy is provided which has high temperature strength and is readily fabricable at ambient temperatures and which is useful as structural elements of liquid metal fast breeder reactors.

Chemical potentials, concentration fluctuations, etc., in binary metal alloys

Abstract: Relationships among transport parameters and the mean square composition fluctuations as determined by measurements of the chemical potentials are described for a variety of binary liquid metal alloys. The measurement of the chemical potential is described and the thermodynamic basis for the analysis given in terms of the concentration correlation functions as well as more traditional thermodynamic parameters. Alloys involving group IIIA metals with Te are used as an example

Titanium or zirconium reduction process by arc heater

Abstract: A process for reducing a metal from a metal halide characterized by the steps of feeding into the arc heated stream of an arc heater a quantity of a reactant metal such as an alkali or alkaline-earth metal, feeding into the arc stream a quantity of a metal halide, which metal has a melting point higher than the boiling point of the co-product salt formed by reduction of the metal, the co-products being a liquid elemental metal and a gaseous salt, projecting the co-products into a reaction chamber tangentially to cause the liquid metal to separate centrifugally from the lighter, gaseous salt, and depositing the liquid metal in an associated receptacle.

Heavy current switchgear with several moving contacts - has at least one solid contact wetted on surface with liq. gallium or its alloy

Abstract: The cooperating surfaces of the two contacts of the heavy current switchgear can be brought together by extension, in order to form a path for the heavy currents. At least one contact consists of a solid conductor (1) with a surface coated with a liquid gallium or its liquid alloy. Preferably both contacts are of the same design. One contact may contain a droplet or a small volume of liquid gallium or its alloy. Typically the liquid alloy contains gallium, indium and/or tin and/or zinc. The connection between the contacts may be attained during switchgear operation by bridging the gap between them with liquid metal. The current path in the switchgear is coaxial and symmetrical in relation to the gap so that no asymmetry magnetic fields are generated.

Superconducting dynamoelectric machine having a liquid metal shield

Abstract: A superconducting synchronous motor or generator which utilizes separate radiation and damper shields around a superconducting field winding on the machine rotor. The damper shield includes a pair of concentrically disposed cylinders held in radial spaced relationship with each other by pillar type structural members. A liquid metal fills the space between the concentric cylinders and as the rotor, including the cylinders, is accelerated to its operating speed, the liquid metal likewise will reach synchronous speed as a result of viscous drag between the liquid metal and the cylinder walls. During operation, the rotor shielding function is performed by the electrically conducting liquid metal moving at synchronous speed during steady state operation. Current generated in the liquid metal shields the superconducting field winding from alternating flux generated in the armature due to phase imbalance and harmonics. During fault conditions, such as a terminal short circuit, currents are generated in the liquid metal to shield the high armature demagnetizing flux from the superconducting winding. These currents in the liquid metal react with the field flux in the air gap to produce body forces in the liquid metal which result in the motion of fluid particles. Forces moving in a radial direction would tend to establish a pressure gradient in the liquid metal, but since the liquid metal is free to move and the pressure gradient cannot be maintained, flow takes place in the space between cylinders to equalize the pressure in the annulus which contains the liquid metal. Also, since circumferential body forces can transmit shear only by viscous forces, the torque reaction is significantly reduced.

Liquid metal current collectors for homopolar machines

Abstract: Results of theoretical and experimental studies of liquid metal current collectors, primarily for segmented-magnet (SEGMAG) drum-type homopolar generators, are presented. Current collectors evaluated are of the rotating disk-stationary concentric channel design The liquid metal is the eutectic sodium-potassium alloy (NaK-78). Power losses and disturbing pressures in the liquid metal were either analyzed or evaluated experimentally in terms of rotor speed, temperature, electric current, and magnetic field for prototypic size current collectors. Specific-contact resistance measurements made using these collectors are reported here.

Vessels for transferring liquid metal having a removable insulating lining

Abstract: The permanent refractory lining of a liquid metal transfer vessel is covered with a removable heat-insulation lining formed of inorganic particles embedded in a binder, the particles being sinterable at the temperature of the liquid metal to be introduced into the vessel. The liquid metal is thus prevented from coming into contact with the permanent lining and any danger of solidification of metal and damage to this latter is consequently removed.

Skull furnace for melting highly reactive metals under vacuum or neutral atmosphere

Abstract: A skull furnace is provided with an expansion vessel filled with neutral gas and communicating with a cooling agent space made in the wall and bottom of a crucible. Used as a coolant is liquid metal cooling agent in which a tubular heat exchanger is immersed. The latter by its one end is connected with a cooling water inlet pipeline and by the other--with an outflow one. The heat exchanger may be constructed to have a double-layer wall with longitudinal passages having at their outlets cooling agent leakage indicators electrically connected with an alarm signalling device.

Apparatus for detecting conductive liquid level

Abstract: An apparatus for detection of the level of a liquid metal is disclosed. The apparatus has a liquid level detecting probe provided with an exciting coil wound in a closed bottom non-magnetic sheath over the approximately whole length thereof, a level detecting coil wound in the sheath in an upper part thereof, and a temperature compensating coil wound in the sheath in a lower part thereof; a temperature control for maintaining the coils at a constant temperature; a drive circuit for supplying the exciting coil with an alternating current of a determined frequency and amplitude; and a signal processing circuit for subjecting output voltages induced in the liquid level detecting coil and in the temperature compensating coil to linear detection and then determining the ratio of the thus detected outputs, thereby detecting the level of the liquid metal. At the time of operation, the liquid level detecting probe is immersed in the liquid metal the level of which is to be detected in such a manner that the temperature compensating coil is always located below the level of the liquid metal.

Hydroperoxy group-containing aluminum compound and method of making the same

Abstract: A hydroperoxy-group-containing aluminum compound is prepared by a process which comprises: Contacting and reacting, at room temperature or below, and in the substantial absence of water, (a) a reactive metal comprising aluminum of a purity of at least 99.9% by weight permeated with a liquid metal selected from mercury, gallium and indium/gallium alloys with (b) a liquid reactant comprising (i) hydrogen peroxide in (ii) a liquid organic compound having no multiple carbon-to-carbon bonds. The aluminum compounds produced can be used, for example, as substrates for electronics, in the preparation of synthetic gems, ceramics and paint pigments. The aluminum compound is prepared in sheet for plate form, resembling mica in physical appearance. In an alternative embodiment, a metal or metal salt is added to the reactive system to yield a hydroperoxy-group-containing aluminum compound with the desired metal deposited thereon.

Droplet size resulting from breakup of liquid at gas-liquid interfaces of liquid-submerged

Abstract: It has been demonstrated both analytically and experimentally (Chawla 1975a; Bell, Boyce & Collier 1972) that, due to existence of the Kelvin-Helmholtz instability at the gas-liquid interfaces of liquid-submerged subsonic and sonic gas jets, liquid at the interface breaks up and becomes entrained in the form of droplets in these gas jets. The study of this phenomenon has numerous industrial applications. For example, in the study of the fuel-failure propagation potential of fission-gas jet impingement in liquid metal cooled fast breeder reactor subassemblies, the liquid entrainment rate and droplet size control the rate of heat transfer in the impingement area of the fission-gas jet (Chawla 1975b). The study of the rate of entrainment and droplet size at the gas-liquid interface of a sonic gas jet submerged in a liquid is also of interest in the field of boiling water reactor safety (Chawla 1975b) and in a number of chemical-engineering processes. An analysis of the rate of liquid entrainment at the gas-liquid interface of a liquid-submerged sonic gas jet has been presented previously (Chawla 1975b). The purpose of the present note is to obtain the droplet sizes due to breakup of the liquid at the interfaces of subsonic and sonic gas jets submerged in a liquid. The existing correlations (e.g. Hinze 1948, 1955) for droplet size do not explicitly include the effect of Mach number or compressibility of gas stream; the present analysis, however, explicitly obtains this dependence for both subsonic and sonic gas jets. 2. ANALYSIS The mechanism of the Kelvin-Helmholtz instability, which is governed by transfer of energy to the liquid layer at the interface through the action of a pressure perturbation in the gas phase against the stabilizing forces due to surface tension and viscosity of liquid (Chawla 1975a), causes the disturbance at the interface to grow with time; when the amplitude of the disturbance becomes large enough, the liquid at the wave crests (protrusions into gas jets) is torn off by a gas jet. The size of the resulting droplets thus formed is obtained by utilizing Taylor's postulate (Taylor 1963) which states that

Characteristics of a Steadily Operating Metal Combustor

Abstract: : The overall objective of the present study was to investigate analytically and experimentally the characteristics of a steadily operating liquid metal thermal energy source employing the lithium-sulfur hexafluoride reactant combination. A steady metal combustor apparatus was designed, fabricated and operated in the temperature range of 1110 to 1255 deg K with power outputs ranging up to 25.2 kW. Steady-state conditions were established by continuously supplying fuel and oxidizer to the reaction chamber while continuously removing the reaction products through a trap arrangement in the bottom of the chamber. Procedures were developed to obtain bath liquid density values and to remove and analyze samples by wet chemical methods. Thermal performance data were generated at a bath temperature of 1197 plus or minus 3 deg K over a range of load conditions. The capability of the system to operate under variable load range, idling and restart conditions was also demonstrated for operating time of 10 hours. No corrosion problems were observed with the type 316 stainless steel components. Thermal efficiencies ranged from 86.4 to 84.0% in the bath temperature range of 1110 to 1250 deg K. Fuel utilization exceeded 99% at 1200 deg K because the fuel solubility in the reaction products is less than 0.5% by mole fraction. A thermodynamic model for the reaction permitted calculation of liquid phase solubilities, liquid phase densities, gas phase partial pressures, and thermal performance values which were in good agreement with experimental results.

Role of energetic mixed-oxide-fuel-sodium thermal interactions in liquid metal fast breeder reactor safety

Abstract: Based upon analysis, numerous experiments and examination of all known occurrences of large-mass vapor explosions, the following general behavior principle has emerged: Mixing of large quantities of a hot and cold liquid, a necessary condition for developing sustained pressures and large damage potential from thermal interaction, requires spontaneous nucleation upon contact. Since the contact temperature for the mixed-oxide-fuel-sodium system is well below the spontaneous-nucleation temperature for liquid sodium, the current interesting controversy regarding spontaneous nucleation and its role in the vapor-explosion mechanism itself is largely irrelevant for this system. Therefore, current practice is to use the pressure-volume curve determined by the expanding fuel vapor following a postulated hydrodynamic disassembly (which generally results from considering a number of unrealistic physical processes to occur) for safety evaluation. It follows that for reactors like FFTF and CRBR, the extremely unlikely event of a core meltdown is predicted to occur safely, with essentially no energetics involved.

Process and apparatus for the continuous casting of metal products

Abstract: Process and apparatus for casting liquid metal in an ingot mold consisting of opposed cooled casting surfaces, at least one of which is convex, and one of which consists of a series of joined shutters. A high pressure is applied to the metal moving between the two surfaces during the solidification of the metal.

Method of making electrical conductors of aluminum-iron alloys

Abstract: The invention concerns electrical conductors of Al-Fe alloys containing from 0.5 to 5% of Fe. Conductors having a highly fibered structure which are stable up to 350° C and have a range of mechanical and electrical characteristics which are remarkable and an excellent surface state are obtained by press drawing of granules of Al-Fe alloys obtained by centrifugal spraying of the liquid metal. Application to electrical conductors in the form of wires, cables and various shaped sections such as flat sections and strips which may be flexible or rigid.

Behavior of Inert Gas Bubbles in Forced Convective Liquid Metal Circuits

Abstract: Conservation equations are derived for the motion of a small inert gas bubble in a large flowing liquid-gas solution subjected to large thermal gradients. Terms which are of the second order of magnitude under less severe and steady-state conditions are retained, thus resulting in an expanded form of the Rayleigh equation. The bubble dynamics is a function of opposing mechanisms tending to increase or decrease bubble volume while being transported with the solution. Diffusion of inert gas between the bubble and the solution is one of the most important of these mechanisms included in the analysis. The analytical model is applied to an argon gas bubble flowing in a weak solution of argon gas in liquid sodium. Calculations are performed for these fluids under conditions typical of normal and abnormal operation of a liquid metal fast breeder reactor (LMFBR) core and the resulting bubble radius, internal gas pressure, and mass of inert gas are presented in each case. An important result obtained indicates that inert gas bubbles reaching the core inlet of an LMFBR will always grow as they traverse the core under normal and extreme abnormal conditions and that the rate of growth is quite small in all cases.

Mercury wettable contact assembly

Abstract: A switching device comprising a movable blade wetted with a liquid metal, and a stationary blade having a surfacelayer of a non-metallic material which is not wetted by the liquid metal.

Apparatus and method for thermal power generation

Abstract: An improved thermal power plant and method of power generation which minimizes thermal stress and chemical impurity buildup in the vaporizing component, particularly beneficial under loss of normal feed fluid and startup conditions. The invention is particularly applicable to a liquid metal fast breeder reactor plant.

Microstructural Changes in Ion-Irradiated Commercial Alloys

Abstract: The effect of heavy ion bombardment on the microstructural stability of several high-nickel superalloys was evaluated by transmission electron microscopy techniques. The work was intended to simulate the type and magnitude of radiation damage occurring with high-fluence exposure in a liquid metal fast breeder reactor (LMFBR) core. Results revealed a general acceleration in precipitation kinetics in alloys with high titanium-to-aluminum ratios, over the temperature range 475 to 725°C (887 to 1337°F). In the Inconel alloys 706 and 718, for example, bombardment produced the stable overaging precipitate n Ni 3 Ti at the expense of the preexisting phases y', y", and δ. Thermal control data over the same temperature range did not reveal the presence of η. Little or no changes in precipitate microstructure were observed in Nimonic PE16, an age-hardenable alloy with a titanium/aluminum ratio of unity.

Preheating method for liquid metal cooled type reactor

Abstract: PURPOSE: A preheating method of a liquid metal cooled type reactor capable of simplifying a necessary structure of preheating device with no maintenance, and capable of heating at an uniform and moderate heating velocity from room temp. to a predetermined preheating temp. COPYRIGHT: (C)1978,JPO&Japio