Showing papers on "Liquid metal published in 1989"

The Integral Fast Reactor

Abstract: The Integral Fast Reactor (IFR) is an innovative liquid metal reactor concept being developed at Argonne National Laboratory. It seeks to specifically exploit the inherent properties of liquid metal cooling and metallic fuel in a way that leads to substantial improvements in the characteristics of the complete reactor system. The IFR concept consists of four technical features: (1) liquid sodium cooling, (2) pool-type reactor configuration, (3) metallic fuel, and (4) an integral fuel cycle, based on pyrometallurgical processing and injection-cast fuel fabrication, with the fuel cycle facility collocated with the reactor, if so desired.

Liquid metal magnetohydrodynamics

Abstract: Session A : Large Interaction Parameter.- Liquid metal in a strong magnetic field (General Lecture).- Numerical solutions of three-dimensional MHD flows in strong non-uniform transverse magnetic fields.- MHD-flows at high Rm, N and Ha.- MHD pressure drop of liquid metal flow in circular and rectangular ducts under transverse magnetic field.- Linear approximation application limits in MHD-flow theory for strong magnetic fields. Experimental results.- Session B : Fusion Related Flows.- Application of the core flow approach to MHD fluid flow in geometric elements of a fusion reactor blanket.- Experimental and theoretical work on MHD at the kernforschungszentrum Karlsruhe. The MEKKA-program.- Liquid metal turbulent flow phenomena and their implications on fusion reactor blanket design.- Experimental investigation of 3-D MHD flows at high Hartmann number and interaction parameter.- Magnetohydrodynamics in nuclear energetics (General lecture).- Poster Session 1 : DC Fields.- Liquid metal flows with polydispersed solid and gaseous inclusions.- Dispersion of small particles in MHD flows.- Two-phase flows studies in mercury-air liquid metal MHD generators.- Liquid metal MHD generators in two-phase flow systems.- Modelling of magnetohydrodynamic two-phase flow in pipe.- Melt magnetohydrodynamics of single crystal growth.- The effect of electromagnetic field on semiconductor single crystal growth and characteristics.- Gas bubbles motion during vacuum treatment of liquid aluminium in MDV-type devices.- MHD turbulence decay behind spatial grids.- The effect of a uniform magnetic field on stability, transition and turbulence as a control means for liquid metal flow mixing.- Session C : Current Carrying Melts.- Electrically induced vortical flows (General lecture).- Liquid metal flow near magnetic neutral points.- Modelling of electrically induced flows for studying current carrying melts of electrometallurgical devices.- Session D : Aluminium Reduction Cells.- Amplitude evolution of interfacial waves in aluminium reduction cells.- Physical and mathematical modeling of MHD-processes in aluminium reduction cells.- On the analysis by perturbation methods of the anodic current fluctuations in an electrolytic cell for aluminium production.- Session E : AC Stirring.- Fluid flows induced by alternating magnetic (General lecture).- Fluid metal flow study in an induction furnace based on numerical simulation.- A high frequency induction furnace for oxide melting.- Directional melt-flow in channel induction furnaces.- Characteristic properties of MHD flow in magnetodynamic pumps.- Session F : Electromagnetic Shaping.- Deflection of a stream of liquid metal by means of an alternating magnetic field.- The shape of liquid metal jets under a uniform transverse magnetic field.- Electromagnetic control of liquid metal free surfaces.- Deformation of an electrically conducting drop in a magnetic field.- Controlled decomposition of liquid metal jets and films in technological and power devices.- Poster Session 2 : AC Fields.- More accurate skin-depth approximation.- Overall and local thickness measurement of layers with differing electrical properties.- Determination of MHD machine parameters using the 1D model of a non-uniform flow.- Experimental and theoretical studies on the stability of induction pumps at large Rm numbers.- 3500 m3/h MHD pump for fast breeder reactor.- Self-excitation of liquid metal MHD generators.- Comprehensive study on the MHD phenomena in the metal pool with the single-phase induction coil.- Grain refinement in continously cast ingots of light metals by electromagnetic casting.- Liquid metal flow control using AC fields.- Session G : Measurements.- Diagnostics of liquid metal flows using fibre-optic velocity sensor.- On local measurements of the up and downstream magnetic wake of a cylinder at low magnetic Reynolds number.- Metallurgical aspects of electromagnetic processing of materials (General lecture).- Session H : Dynamo Theory.- Liquid metal MHD and the geodynamo (General lecture).- The helical MHD dynamo.- The Ponomarenko dynamo.- MHD phenomena in fast neutron reactors with a liquid metal heat carrier.- Session I : Turbulence.- The effect of initial and boundary conditions upon the formation and development of MHD turbulence structure.- Two-dimensional MHD turbulence.- MHD instabilities and turbulence in liquid metal shear flows.- Session J : Stability with Uniform Field.- Dispersion and chaos in linear arrays of vortices.- Stability of magnetohydrodynamic flow over a stretching sheet.- Stability of closed azimuthal jet of liquid metal.

The metal-insulator transition in expanded fluid metals

Abstract: Over the past two decades, a considerable amount of effort has been centered on the experimental and theoretical investigation of liquid metals expanded by heating toward the liquid-vapor critical point. Much of the activity is motivated by the large number of current and potential applications of fluid metals as high temperature working fluids for advanced energy technologies. From the scientific point of view, the main object of this effort is to find out how the properties of metals vary with large changes in density, large enough to change the liquid metal into a nonmetal at large enough expansion. Figure I shows why such a metal to nonmetal transition must occur with decreasing density. The discontinuous liquid-vapor phase change of a metal at low temperatures near the triple point is obviously accompanied by a discontinuous metal(M)-insulator(I) transition. In such a situation the liquid metal is reasonably well described by the nearly-free-electron model, whereas in the dilute insulating vapor the great majority of the electrons are attached to their parent atoms occupying spatially localized atomic orbitals. It follows that the precise nature of the electronic interactions between atoms must change on going by a suitable combination of temperatures and pressures continuously along the dashed path round the critical point from the liquid-like (M) to vapor-like (I) densities. Somewhere along this line a transition range must exist where metallic properties evolve into those characteristic of non­ metals.

High intensity x-ray source using liquid gallium target

Abstract: A high intensity x-ray source that uses a flowing stream of liquid gallium as a target with the electron beam impinging directly on the liquid metal.

Metal drilling with a CO2 laser beam. II. Analysis of aluminum drilling experiments

Abstract: The penetration time, crater top radius, and melted zone for aluminum plates drilled with a CO2 laser beam have been measured and analyzed on the basis of various assumptions concerning absorptivity of the liquid metal, attenuation by the metal vapor and heat exchange with the vapor. By comparison with the experimental data it is shown that each of the interaction parameters must lie within a predetermined range in order to correlate all the experimental measurements. This ascertains the reliability of the theoretical approach and yields estimates of the a priori unknown parameters for the specific exposure conditions.

Process for treating liquid metals

Abstract: A process for treating metal comprises applying a positive DC potential to an ionic melt layer disposed on the surface of a liquid metal. The application of this potential provides a plasma phase above the ionic melt layer and induces a flow of electrons from the liquid metal towards the plasma phase. The ionic melt layer is capable of being maintained in a liquid state when it is in contact with the liquid metal. The process can be used either to remove impurities from the liquid metal, to alloy the liquid metal by adding metal compounds in the ionic melt layer, to recover metals from waste, or to perform a combination of these functions. An apparatus for treating liquid metals is also provided.

Method for passive cooling liquid metal cooled nuclear reactors, and system thereof

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.

Diffusion-controlled startup of a gas-loaded liquid-metal heat pipe

Abstract: Liquid-metal heat pipes have exhibited difficulties starting up from a frozen-state. Inert gas loading is a possible solution to the frozen-state startup problem. The present study deals with the diffusion-controlled startup analysis and testing of an argon-loaded, 2-m-long, stainless steel-sodium heat pipe of the double-walled type with artery channel and long adiabatic section. A two-dimensional, quasi-steady state, binary vapor-gas diffusion model determined the energy transport rate of vapor at the diffusion front. The analytical solution to the diffusion problem provided the vapor flux, which in turn was used in the one-dimensional transient thermal model of the heat pipe to predict the time rate-of-change of temperature and position of the hot front. The experimental test results successfully demonstrated the startup of a gas-loaded sodium heat pipe and validated the diffusion model of the startup. 17 refs.

Studies on the Startup Transients and Performance of a Gas Loaded Sodium Heat Pipe

Abstract: : High temperature liquid metal heat pipes have exhibited difficulties starting up from frozen state due to inherent low near-room temperature vapor pressures associated with working fluids. Inert gas loading is a possible solution to the frozen state startup problem. A few research papers give results of this technique. The applicability of the method to heat pipes with arterial grooves and long adiabatic lengths is unknown. the present study deals with the design, fabrication and startup testing of a gas loaded sodium heat pipe of the double walled type with grooved artery channel and long adiabatic section. Artery, Startup, Noncondensible gas, Frozen start, Diffusion model, Reservoir wick, Heat front, High temperature, Liquid metal, Sodium, Transient analysis.

Magnetohydrodynamic stability in the electromagnetic levitation of horizontal molten-metal sheets

Abstract: High‐frequency electromagnetic (EM) fields are investigated for the levitation of thin horizontal sheets of liquid metal. A magnetic configuration is analyzed in which inductance stabilization provides global stability and magnetic flux compression provides local stability. Stability analysis indicates that frequencies greater than about 24 kHz are desirable to stably levitate 6 mm thick steel. For stability in systems without active feedback, a conducting screen is required below the metal, with a gap between the screen and the molten metal of no more than twice the metal thickness. Experiments in which 10 kHz EM fields were used to statically levitate sheets of molten tin indicate that dominant magnetohydrodynamic instabilities are of the Rayleigh–Taylor type and correspond to theory.

On the onset voltage of liquid metal ion sources

Abstract: Various formulae for the onset voltage corresponding to liquid metal ion sources (LMIS) of different design are compared to a wide range of experimental data. Provided the correct formula is used in each particular case, the agreement between theory and experiment is satisfactory. Predicting the source starting voltage correctly is of use in ion source and ion column design.

MHD Pressure Drop of Liquid Metal Flow in Circular and Rectangular Ducts under Transverse Magnetic Field

Abstract: Simple formulas were derived to estimate the liquid metal MHD pressure drop in a cooling system for fusion use and good agreements were obtained with NaK and Li experiments in use of various SS ducts.

Heat Transfer in Rectangular First Wall Coolant Channels of Liquid-Metal-Cooled Blankets*

Abstract: Heat transfer in magnetohydrodynamic flow of a liquid metal in rectangular ducts with thin conducting walls in the presence of a large transverse magnetic field is examined A significant fraction of the fluid flow, in the form of high velocity jets, is confined within the boundary layers (side layers) adjacent to the side walls which are parallel to the magnetic fields The existence of the high velocity jets may drastically enhance the cooling capacity Two schemes - integral and explicit - for the treatment of the flow in the side layers are discussed Heat transfer calculations based on these schemes are compared

Diagnostics of Liquid Metal Flows Using Fibre-Optic Velocity Sensor

Abstract: The present work is connected with a theoretical and experimental study of the application of two-component fibre-optic velocity sensors for diagnostics of liquid metal turbulent flow. The above sensors have high spatial resolution (10−3mm3) and exhibit insignificant sensitivity to admixtures and the magnetic field; they could also be used for liquid metals in the presence of strong currents (≈10 A). The experimental data on the velocity fields and intensity of its pulsations in strongly nonuniform liquid metal magnetohydrodynamic flows are given. Dynamical errors of velocity measurements at a frequency of 200 Hz are negligible.

Thermal conductivity of lead in the range -180 to 500°C

Abstract: The thermal conductivity of lead (99.99%) has been measured in the range −180 to 500°C using four measuring devices (steady-state method). The thermal conductivity of both solid and liquid lead can be represented as a linear function of the temperature. The uncertainty of the measured values is estimated at 2.5% (solid) and 3% (liquid). Between the melting point and 500°C, the thermal conductivity increases by 14%. The ratio of the thermal conductivity of solid to liquid lead at the melting point corresponds to the ratio of the electric conductivities. The Lorenz function for liquid lead is approximately 1% above the ideal value at the melting point and some 3% lower than the ideal value at 500°C.

Development of aperiodic instability on liquid metal surface perturbed by thermal fluctuations

Abstract: The dynamics of a liquid metal layer in a strong electric field is investigated for arbitrary viscosity. The specific forms of microtip that appear when aperiodic instability develops are determined. The liquid surface correlation function for development of instability on thermal fluctuations is calculated. >

Apparatus for stirring molten metal

Abstract: The invention provides a new stirring apparatus for stirring the liquid metal contents of a furnace, particularly the shallow furnaces used in the processing of aluminum and its alloys. The apparatus consists a reservoir separate from the furnace of relatively large horizontal cross-section and volume, into which a vaccuum draws metal from the furnace through a nozzle, the metal then being returned by gas pressure forcibly into the furnace through the nozzle in the form of a horizontally directed jet. The cycle is repeated at sufficiently close intervals to ensure that the furnace bath is quickly and effectively mixed. The nozzle directs the molten metal entering the reservoir tangentially to swirl the metal and reduce the accumulation of dross. The reservoir comprises a bottom static part including the nozzle and a readily removable top cover carrying heaters for heating the reservoir interior and the dross that deposits on the side wall to ease its removal. The cover also carries level control electrodes, an observation port, inlet ports, etc. A pressure disturbance monitor connected to the reservoir interior is used for lower level control by detecting undesired bubbling of the pressurizing gas into the metal, and can also be used to monitor the pressure reversals between vacuum and pressurization phases. The cycles of vaccuum and pressure are controlled in a manner that maximizes the quantity of metal entering the reservoir so as to obtain the maximum stirring effect.

Thermohydraulic Investigations of Decay Heat Removal Systems by Natural Convection for Liquid-Metal Fast Breeder Reactors

Abstract: This paper reports, to examine the function of the safety-related SNR-2 decay heat removal concept, natural convection experiments performed in two-and three-dimensional water models, scaled 1:20, under conditions of symmetric and nonsymmetric loads of the immersed coolers installed in the upper plenum at 180-deg positions with respect to each other. The temperature and velocity distributions were measured and the flow patterns recorded for different configurations of the instrumented plug. For symmetric load conditions, symmetric temperature and flow distributions were measured in two- and three-dimensional models. Nonsymmetric load conditions produce remarkable temperature differences between the two separated plenums of the two-dimensional model if fluid circulation is suppressed by a closed plug. An open plug allows fluid to pass through and shows lower temperature differences. In contrast, in the three-dimensional experiment, azimuthal fluid flow inside the plenum prevails even with the plug closed, and identical temperature distributions are measured. The calculations using the COMMIX-1B code are generally in good agreement with the measurements.

The emission characteristics of an indium needle-type liquid metal ion source

Abstract: Operational data for an indium needle-type liquid metal ion source are presented. Detailed comparisons are drawn between these characteristics and those of a similar gallium source. The behaviours of the two sources are found to be strikingly similar, indicating a common mechanism of ion emission.

Mass spectra of AuGe alloy liquid metal ion sources

Abstract: Measurements are reported on the mass spectrum of a AuGe alloy liquid metal ion source with various alloy compositions and values of total source current. To obtain a high fraction of Ge ions, it is advantageous to use an alloy composition with a higher germanium content than that of the eutectic composition. It is shown that the fraction of Ge2+ ions varies within a small range depending on the total source current, whereas the Ge+ fraction increases with increasing current. A strong isotopic effect for the Ge+2 fraction could be observed which may be explained by charge transfer reactions. The temperature range of the coexistence of the solid and liquid phase of the investigated alloys was determined by the method of differential thermal analysis (DTA).

Self-refining molten metal fuel furnace

Abstract: PURPOSE:To execute the retreatment of used fuel with compact equipment and simplified process by forming a low melting plutomium and/or uranium alloy fuel phase, low melting salt phase and gas plenum successively from below to above in each fuel element. CONSTITUTION:The low melting plutonium and/or uranium alloy fuel phases 3 which melt at the operating temp. of a reactor furnace, the low melting salt phases 4 and the gas plenums 5 are formed in this order successively from lower to upper layers in the respective fuel elements 1a of the reactor vessel in which a liquid metal is used as a coolant and is disposed with the plural fuel elements in the cores. The alloy fuel phases 3 are thereby burned in the molten state during the reactor operation. The fission gases generated at this time are collected in the gas plenums 5 and the fission products are partly transferred to the salt phases 4 in the molten state, by which the self-refining function is provided to the alloy fuel phases 3 in the fuel elements 1a.

Light-Material Interactions In Laser Material Processing

Abstract: Light interactions with materials in laser material processing operations occur by a variety of mechanisms depending on the material being processed, the wavelength of the laser light, the gaseous environment, and the physical state of the material surface. The high reflectivity of metals limits the fraction of the beam power absorbed by the solid metal surface. For metals in the solid state, reflectivity increases as the wavelength of the laser light and the electrical conductivity of the metal increase. The reflectivity of metals is reduced upon heating to the melting point, and further reduced upon melting. At high power densities the liquid metal surface is heated so quickly that very rapid vaporization occurs. The recoil force produced by the evaporation causes a depression in the liquid/vapor interface. The "keyhole" resulting from this depression allows for multiple reflections and thus increases beam absorption into the liquid. The vaporized metal above the liquid surface can cause attenuation of the beam. Both plasma absorption and fine particle scattering theory have been proposed to account for this beam attenuation. The attenuation is strongly affected by shielding gas type and pressure. In the laser cutting the beam interacts with the material through a high angle of incidence. Under these conditions the degree of beam polarization becomes important.

Carbonaceous coating for refractory filters of liquid metals

Abstract: This invention discloses a process for making a refractory filter for liquid ferrous and non-ferrous metal with improved priming action A carbonaceous resin onto the surfaces of a hard-fired ceramic or refractory cloth filter for liquid metal which protects the filter against abrasion and the absorption of water and also holds and protects particulate additives in place on the surface of the filter where they can later react with the liquid metal When the liquid metal approaches and then touches the surface of the filter, the resinous coating chars The resulting porous layer of mechanically strong carbon retards heat transfer from the hot liquid metal to the otherwise unheated filter, aiding the priming of the filter and also controlling the rate of dissolution of the particulate additives into the liquid metal The preferred resin has a high char-forming tendency and a mechanically strong porous carbon coating on the filter when the filter is exposed to the hot, liquid metal