Liquid Cd Research Articles

Thermochemical modelling of electrotransport of uranium and plutonium in an electrorefiner

Electrotransport behaviour of U and Pu in a molten salt electrorefining cell has been numerically simulated with an improved thermochemical model. Depending upon saturated or unsaturated states of the liquid Cd electrodes with respect to U or Pu or with both U and Pu, 16 conditions of electrorefiner cell operation have been categorised and electrotransport simulated for all the realistic conditions. Algebraic equations for determining the compositions of the salt phase and the two electrodes under each condition of electrotransport are derived. Fractional mass transport coefficients and relative fractional mass transport coefficients are derived for each condition to illustrate the electrotransport behaviour. Comparison is made between modeling with concentration dependent and concentration independent activity coefficients for U and Pu in liquid Cd. The electrotransport to a solid cathode and anodic dissolution have also been simulated. Application of the model to reprocessing of spent metallic fuel is discussed with respect to U recovery, Pu enrichment and reconstitution of the spent fuel with desired fuel composition.

Conformational stability and vibrational assignment of propanal

Variable temperature (−52 to −100°C) studies of the infrared spectra (3500–400 cm −1) of propanal, CH 3CH 2CHO, dissolved in liquid xenon have been recorded and bands due to both the cis and gauche conformers have been identified. From these data, the enthalpy difference has been determined to be 370±21 cm −1 (4.43±0.25 kJ mol −1) with the cis conformer (methyl group eclipsing the oxygen atom) the more stable form. Utilizing the new infrared data from the xenon solution, along with some additional Raman data, and ab initio predictions from MP2/6-31G* calculations, several reassignments of the fundamentals have been made for the cis conformer. Additionally, several bands which have been identified as arising from the gauche conformer have also been assigned. Infrared (3500–80 cm −1) and Raman (3500–30 cm −1) spectra of gaseous, liquid and/or solid CD 3CD 2CHO are also reported and the fundamentals assigned for the cis conformer. The spectroscopic and theoretical results are compared to the corresponding quantities for some similar molecules.

Nutridation of uranium and rare-earth metals in liquid Cd

The nitride formation reaction of liquid 2 wt% U-1 wt% Gd-1 wt% Ce Cd alloys has been studied over the temperature range of 773–873 K using graphite and molybdenum crucibles. Uranium was preferentially nitrided to form U 2N 3, which were produced at the nitrogen gas-liquid alloy interface. A little gadolinium was precipitated as nitrides, GdN or the (U, Gd)N phase. Almost all of the cerium and some gadolinium remained in the Cd phase as MCd 11 intermetallic compounds. Resistance of Ce to nitridation is due to the lower activity coefficients in a Cd-rich solution at these temperatures.

Electrodeposition of uranium in stirred liquid cadmium cathode

The electrodeposition of U in a liquid Cd cathode was known to be hampered by the formation of dendritic U on the Cd surface. Electrotransports of uranium to the stirred liquid Cd cathode were carried out at 773 K for different cathode current densities and different Reynolds number of stirring. The maximum amount of U taken in the liquid Cd cathode without forming dendrites was found to increase with an increasing Reynolds number of stirring and decrease with increasing cathode current density.

Temperature dependence of the static structure factor of the non-simple liquid metal, Cd

Report a calculation of the static structure factors at any temperature for the non-simple liquid metal Cd by the method of model parameter based on the hard sphere cluster (HSC) model. In comparison with available experimental data, the theoretical results are in good agreement with experiments.

Molar Volume and Compressibility of the Liquid Cd–Sb System

Thermodynamic properties of the liquid Cd–Sb system has been investigated by measuring the molar volume and sound velocity over the whole composition range as a function of temperature. The volume expansion coefficient and the isothermal compressibility have been deduced. These thermodynamic functions for alloys around 50 at.%Cd show very large temperature dependence in a rather small temperature interval adjacent to the liquidus line. Their dependences on temperature and composition conform to cluster formation and rapid structural changes in liquid Cd–Sb alloys.

Investigation of Cell Resistance for Molten Salt Electrorefining of Spent Nuclear Fuel

Cell resistance for molten salt electrorefining of spent nuclear fuel under various electrode configurations was investigated by using the two-dimensional finite element method. Three electrorefining cell configurations were evaluated; (1) a liquid Cd anode and a solid cathode made of low carbon steel with or without a ceramic plate at the bottom, (2) a liquid Cd anode and a liquid Cd cathode, and (3) two anodes in the form of a perforated steel basket filled with spent nuclear fuel and two solid cathodes, in two different arrangements. The calculated results agreed reasonably well with previously obtained experimental data. The effect of polarization on the cell resistance was found to be small for a typical uranium concentration in the molten salt electrolyte and the liquid Cd anode. The calculation results are helpful in interpreting experimental data, and a correlation formula was developed that may be useful in estimating the cell resistance of new cell designs.

Investigation of Cell Resistance for Molten Salt Electrorefining of Spent Nuclear Fuel.

Cell resistance for molten salt electrorefining of spent nuclear fuel under various electrode configurations was investigated by using the two-dimensional finite element method. Three electrorefining cell configurations were evaluated; (1) a liquid Cd anode and a solid cathode made of low carbon steel with or without a ceramic plate at the bottom, (2) a liquid Cd anode and a liquid Cd cathode, and (3) two anodes in the form of a perforated steel basket filled with spent nuclear fuel and two solid cathodes, in two different arrangements. The calculated results agreed reasonably well with previously obtained experimental data. The effect of polarization on the cell resistance was found to be small for a typical uranium concentration in the molten salt electrolyte and the liquid Cd anode. The calculation results are helpful in interpreting experimental data, and a correlation formula was developed that may be useful in estimating the cell resistance of new cell designs.

A simple scaling formula and monte carlo study of liquid semiconductor surfaces: application to Cd xTe 1− x

Crystal growth of semiconductor compounds in a microgravity environment depends on the temperature- and concentration derivatives of surface tension. In such situations, gravity-driven convective forces are suppressed, and the dominant one is the so-called Marangoni connection, which is driven by surface tension gradients parallel to the surface. A particularly interesting material from this point of view is liquid Cd[sub x]Te[sub 1[minus]x]. In its solid phase, only a single stoichiometric compound exists, and this is nearly insoluble in either pure Cd or pure Te. The liquid phase forms a continuous solid solution at all temperatures above the liquidus. The stoichiometric compound is semiconducting, with a very low electrical conductivity of [approximately] 90 [Omega][sup [minus]1] cm[sup [minus]1] at the melting temperature. As a first step in understanding nonstoichiometric Cd[sub x]Te[sub 1[minus]x], the authors describe in this paper Monte Carlo calculations for such alloys using the same potentials as used for x = 0.50. These lead to the apparently anomalous prediction that the surface tension of Cd[sub x]Te[sub 1[minus]x] is a nonmonotonic function of x. While there are no available experimental results for Cd[sub x]Te[sub 1[minus]x] with determined x except at x = 0.5, other semiconductor alloys do exhibit such an anomaly, whichmore » is therefore evidently accounted for by the empirical potentials. In order to shed more light on this anomaly, they also analyze it by means of a scaling formula for the surface tension, which they have briefly introduced in a previous paper. This scaling formula permits them to calculate the surface tension from only two parameters in the potentials. Here, they apply this scaling formula to other elemental and compound liquid semiconductors as well as to off-stoichiometric CdTe. The scaling results are in good agreement with the Monte Carlo results and available experiments.« less

Evaluation of liquid metal embrittlement of stainless steel 304 by cadmium and cadmium-aluminum solutions

The susceptibility of stainless steel 304 (SS304) to liquid metal embrittlement (LME) by cadmium (Cd) and cadmium-aluminum (Cd-Al) solutions was examined as part of a failure evaluation for SS304-clad cadmium reactor safety rods which had been exposed to elevated temperatures. The safety rod test data and destructive examination of the specimens indicated that LME was not the failure mode. The available literature data also suggest that austenitic stainless steels are not particularly susceptible to LME by Cd or Cd-Al solutions. However, the literature data is not conclusive and an experimental study was therefore conducted to examine the susceptibility of SS304 to LME by Cd and Cd-Al solutions. Temperatures from 325 to 600°C and strain rates from 1 × 10 −6 to 5 × 10 −5 s −1 were of interest in this evaluation. Tensile tests carried out in molten Cd-Al and Cd solutions over these temperatures and strain rates with both smooth bar and notched specimens showed no evidence of LME. U-bend tests conducted in liquid Cd at 500 and 600°C also showed no evidence of LME. It is concluded that SS304 is not subject to LME by Cd or Cd-Al solutions over the range of temperatures and strain rates of interest.

Coherent propagation of subpicosecond pulses in the mid-infrared in condensed matter

Propagation of tunable pulses of 0.7 ps in the ir around 5 μm is investigated in the case of small intensity and a moderately short sample. Coherent pulse reshaping is observed and exploited to measure the dephasing time of the CD 3-stretching vibration ν 1 of liquid and solid CD 3I in the temperature range 296-180 K.

Concentration fluctuations and thermodynamic properties of demixing liquid binary alloys

An optimized set of thermodynamic functions of liquid CdGa and BiGa alloys is obtained by a least-squares method through optimization of different available experimental data such as phase diagram and thermodynamic properties. These results can be described using a simple model, where the existence of polyatomic self-associates has been considered. The temperature and concentration fluctuations in the long wavelength limit, which are most sensitive to small changes in both temperature and concentration above the miscibility gap, can be described assuming a temperature dependence of the number of self-associated atoms and of the interchange energy.

The enthalpy of formation of the CdGaZn liquid system

Using a high-temperature Calvet calorimeter, the molar enthalpies of formation (Δ mix H m = f( x Cd, x Zn)) of the liquid Cd + Ga + Zn alloys were measured at 730 K over a large molar fraction range. The direct drop method (successive additions of solid cadmium and solid zinc) was used to synthesize alloys in the cell of the calorimeter. In agreement with thermodynamic data and equilibrium phase diagrams of limiting binary systems which exhibit either a eutectic point or a miscibility gap, the enthalpy of formation of the liquid Cd + Ga + Zn system is slightly endothermic (extremum value 3.0 kJ mol −1). Experimental values of Δ mix H m = f( x Cd, x Zn) are compared with those predicted from the Kohler, Muggianu, Hoch—Arpshofen and Mathieu relations.

Thermodynamic studies and phase diagrams of the Cd-Ga-In system

Calorimetric and vapor pressure data of liquid Cd- Ga- In alloys were measured. From these data an optimized set of thermodynamic parameters of the Cd- Ga- In system was derived using the leastsquares method. The thermodynamic parameters of the binary subsystems were taken from the literature and combined to a ternary description by the Muggianu formula. This description was augmented by a ternary term for the liquid phase, described as a function of temperature and concentration by six coefficients.

Molecular dynamics in liquid CD 3NO 2 from Raman bandshapes

Vibrational bandshapes of totally symmetric ν 3, ν 4 and ν 5 motions of liquid deuterated nitromethane have been studied as a function of temperature and, for ν 5, also of concentration in CH 3NO 2 solutions. Correlation functions for ν 4 and ν 5 modes are calculated, and hypotheses about vibrational relaxation mechanisms are presented.

Equilibrium distribution of rare earth elements between molten KCl-LiCl eutectic salt and liquid cadmium

Distribution experiments for several rare earth elements (La, Ce, Pr, Nd and Y) between molten KCl-LiCl eutectic salt and liquid Cd were carried out at 450, 500 and 600°C. The material balance of rare earth elements after reaching the equilibrium and their distribution and chemical states in a Cd sample frozen after the experiment were examined. The results suggested the formation of solid intermetallic compounds at the lower concentrations of rare earth metals dissolved in liquid Cd than those solubilities measured in the binary alloy system. The distribution coefficients of rare earth elements between two phases (mole fraction in the Cd phase divided by mole fraction in the salt phase) were determined at each temperature. These distribution coefficients were explained satisfactorily by using the activity coefficients of chlorides and metals in salt and Cd. Both the activity coefficients of metal and chloride caused a much smaller distribution coefficient of Y relative to those of other elements.

Characterization of electrochemical photovoltaic cells using polycrystalline CdSe and CdTe electrodes grown by a liquid metal-vapor reaction

Polycrystalline CdSe and CdTe layers were fabricated by putting liquid Cd in contact with Se or Te vapors under constant Ar flow. The crystalline structure, surface properties, and semiconducting properties of these materials have been determined. Both materials were found to be n-type semiconductors. The results show that, under the proper experimental conditions, the liquid metal-vapor reaction enables the synthesis of polycrystalline CdSe photoelectrodes with a 6.9% energy conversion efficiency when used in an electrochemical photovoltaic cell under 80 mW/cm2 of white light illumination. This efficiency rates amongst the highest ones measured under similar conditions using polycrystalline CdSe. These CdSe layers have a majority charge carrier density of ND = 2.6 × 1017 cm−3 and possess a highly textured surface which is assumed to be mainly responsible for the high photovoltaic efficiency. The highly textured CdTe samples obtained by this process, however, show a photovoltaic conversion efficiency of only 0.2%, and this is seen to be mainly due to their high majority charge carrier density of ND = 7.8 × 1019 cm−3.

Infrared Dispersion and Vibrational Intensities of Liquid CD3I

Infrared Dispersion and Vibrational Intensities of Liquid CD₃I

The infrared dielectric function of liquid CD 3CN

The complex electric permittivity spectrum in the mid-infrared region is obtained for liquid CD 3CN. The molar vibrational polarizations for the principal absorption regions of this molecule are determined and discussed.

The vibrational spectra of CD 3SH and CD 3SD in various phases and of CH 3SH and CH 3SD in the torsion vibration region of the two solid phases

Knowledge of the vibrational spectra of CH 3SH, CH 3SD, CD 3SH and CD 3SD is expanded. Measurements of liquid CD 3SH and CD 3SD correspond to a former determination of an inverse vapor pressure isotope effect, even though association exists. Investigation of the four solid compounds in the low-frequency range permit identification of the torsion modes of the low-temperature phase as doublets between 200 and 400 cm −1. The splitting of these doublets by ∼100 and 60–70 cm −1 is as large as for solid methylamine and methanol, but differs from the alcohol and cannot be explained exclusively by intermolecular coupling. Like the splitting of the close-spaced doublets of the SH or SD stretching vibrations, it is caused partly by coupling and partly by the presence of different types of sites of the unit cell. Corresponding to the changed crystal structure and to the weaker hydrogen bonding, the torsion modes of the high-temperature phase appear as triplets or quartets at lower wave numbers.