The Gibbs free energy of forming gallium sesquioxide and indium sesquioxide are measured using a CO$sub 2$--CO--O$sub 2$ gas reference electrode and calcia stabilized zirconia as the solid electrolyte. The free energies are: $delta$G$sup 0$/sub f/($beta$-Ga$sub 2$O$sub 3$(c)) equals -(265,309 +- 152) + (82.47 +- 0.16) (T/K) cal mol$sup -1$ and $delta$G$sup 0$/sub f/(In$sub 2$O$sub 3$ (c)) equals -(223,160 +- 137) + (79.47 +- 0.12) (T/K) cal mol$sup -$.$sup 1$ A solid state galvanic cell is employed to measure gallium activities in Ga--Sb liquid alloys. Results show moderate negative deviations from ideality in the composition range 0.039 less than x/sub Ga/ less than 0.833. Partial molar enthalpies and entropies are calculated, and agree wih calorimetric data. Results are combined with calorimetric data to calculate the liquidus temperatures of the Ga--Sb system, which are in excellent agreement with measurements. Effect of short-range ordering is also investigated. Coulometric titration techniques are used to investigate the solubility and diffusivity of oxygen in liquid indium. Dissolved atomic oxygen is found to follow Henry's law and a saturation solubility of x$sub 0$/sup sat/ equals 3.3 x 10$sup -3$ is determined at 908$sup 0$K. From a galvanostatic response of an indium electrode, an oxygen diffusivity of …

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Optical properties of Nb alloys were investigated. Calorimetric measurements of absorptivity between 0.2 and 5.5 eV were taken for Nb samples with 20, 50, and 80 percent Mo and for Nb samples containing 10 percent Zr, 20 percent V, and 20 percent Ta. Reflectivity data for two of these samples in the ultraviolet region and known reflectivities for the pure metals to 35 eV provided the basis for extrapolation to high energies. The data were Kramers--Kronig analyzed to determine the dielectric function. The structure is discussed in terms of interband transitions as predicted by a rigid band model for the NbMo alloys. (auth)

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The driven coupled mode equations are derived for a two fluid, unequal temperature (T/sub e/ much greater than T/sub i/) plasma in the one-dimensional, electrostatic model and applied to the coupling of electron plasma waves. It is assumed that the electron to ion mass ratio identical with m/sub e/M/sub i// much less than 1 and eta$sup 2$/sub ko/k lambda/sub De/ less than 1 where eta$sup 2$/ sub ko/ is the pump wave's power normalized to the plasma thermal energy, k the mode wave number and lambda/sub De/ the electron Debye length. Terms up to quadratic in pump power are retained. The equations describe the linear plasma modes oscillating at the wave number k and at $omega$/sub ek/, the Bohn Gross frequency, and at $Omega$/sub k/, the ion acoustic frequency, subject to the damping rates $nu$/sub ek/ and $nu$/sub ik/ for electrons and ions and their interactions due to intense high frequency waves E/sub k//sup l/. n/sub o/ is the background density, n/sub ik/ the fluctuating ion density, $omega$/sub pe/ the plasma frequency. (auth)

The thermal conductivity, Seebeck coefficient, and electrical resistivity of four high purity vanadium samples have been measured as functions of temperature over the temperature range 5 to 300$sup 0$K. The highest purity sample had a resistance ratio (rho/sub 273$sup 0$K//rho /sub 4.2$sup 0$K/) of 1524. The highest purity sample had a thermal conductivity maximum of 920 W/mK at 9$sup 0$K and had a thermal conductivity of 35 W/mK at room temperature. At low temperatures the thermal resistivity was limited by the scattering of electrons by impurities and phonons. The thermal resistivity of vanadium departed from Matthiessen's rule at low temperatures. The electrical resistivity and Seebeck coefficient of high purity vanadium showed no anomalous behavior above 130$sup 0$K. The intrinsic electrical resistivity at low temperatures was due primarily to interband scattering of electrons. The Seebeck coefficient was positive from 10 to 240$sup 0$K and had a maximum which was dependent upon sample purity. (auth)

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The application of fault tree analysis (FTA) to system safety and reliability is presented within the framework of system safety analysis. The concepts and techniques involved in manual and automated fault tree construction are described and their differences noted. The theory of mathematical reliability pertinent to FTA is presented with emphasis on engineering applications. An outline of the quantitative reliability techniques of the Reactor Safety Study is given. Concepts of probabilistic importance are presented within the fault tree framework and applied to the areas of system design, diagnosis and simulation. The computer code IMPORTANCE ranks basic events and cut sets according to a sensitivity analysis. A useful feature of the IMPORTANCE code is that it can accept relative failure data as input. The output of the IMPORTANCE code can assist an analyst in finding weaknesses in system design and operation, suggest the most optimal course of system upgrade, and determine the optimal location of sensors within a system. A general simulation model of system failure in terms of fault tree logic is described. The model is intended for efficient diagnosis of the causes of system failure in the event of a system breakdown. It can also be used to assist …

The $sup 2$D quadrupole interaction was observable in all the samples of LaNi$sub 5$D/sub x/ up to a critical temperature T/sub c/ at which the intensity of the quadrupole interaction spectrum disappeared and only a narrow unsplit line remained. The critical temperatures were 360$sup 0$K for the x = 3.6 sample and 380$sup 0$K for the x = 5.7, 6.7 samples. Based on preliminary electric field gradient (EFG) calculations, it appears likely that several quadrupole interactions are being observed from inequivalent deuterium sites in the lattice. In the temperature range T greater than or equal to 300$sup 0$K, it appears that diffusional averaging is not entirely isotropic and that the deuterium still occupies certain interstitial sites preferentially. The temperature dependence of the $sup 2$D characteristic quadrupole frequency ($nu$/sub Q/) and the disappearance of the $sup 2$D quadrupole interaction signal were found to be compatible with desorption of the deuterium from the LaNi$sub 5$ lattice with increasing temperature. Spectra obtained from D$sub 2$ gas samples under various experimental conditions (pure gas, gas above LaNi$sub 5$D$sub 6$.$sub 7$, and gas within or on LaNi$sub 5$ at 77$sup 0$K) may provide evidence for the identification of the solid-solution $alpha$-phase or for the existence …

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Evaporated films of La, Ce, Yb, Y, Ag--Mn(5 percent), KCl, MnF$sub 2$, CsCl and LaF$sub 3$ were studied using the soft x-ray appearance potential spectroscopy (SXAPS) technique. Studies were also made of bulk polycrystalline samples of Y, Zr, Nb, and Mo. The results are discussed in terms of existing SXAPS theories. Several similarities between soft x-ray absorption (SXA) data and the SXAPS results are discussed, and it is shown that the SXA data can aid in the interpretation of SXAPS spectra when using the well-known self-convolution model. In this approximation the absorption coefficient, $alpha$(E), is substituted for the density of states, N(E-E/sub c/) $Yields$ $alpha$(E). For more localized excitations, a convolution of $alpha$(E) with bremsstrahlung isochromat data, based on Wendin's two density of states formalism is used to predict SNAPS results. (auth)

Europium oxide is presently being tested for use as the control material in future nuclear power reactors. Elastic properties of europia and selected europia-rich compositions of the europia-hafnia system were investigated. The sonic technique was employed to measure elastic moduli from room temperature to 1500$sup 0$C. Sintered monoclinic europia specimens were found to have uncommonly low room temperature moduli values and to exhibit hysteresis between heating and cooling curves because of the presence of microcracks caused by thermal expansion anisotropy. Fine grained hot pressed europia as well as sintered specimens that contained at least 6 mole percent hafnia did not exhibit these characteristics. Photomicrographs revealed that grain growth suppression was produced by and related to the amount of hafnia introduced. Hysteresis loops in the moduli versus temperature measurements were exhibited only by those specimens for which the average grain size was in excess of a critical value of 8 $mu$m. Dilatometer measurements indicated that thermal expansion was relatively constant over the compositional range of interest. (auth)

The oxygen-to-metal atom ratio, or O/M, of solid solution uranium- plutonium oxide reactor fuel is a measure of the concentration of crystal defects in the oxide which affect many fuel properties, particularly, fuel oxygen potential. Fabrication of a high-temperature oxygen electrode, employing an electro-active tip of oxygen-deficient solid-state electrolyte, intended to confirm gaseous oxygen potentials is described. Uranium oxide and plutonium oxide O/M reference materials were prepared by in situ oxidation of high purity metals in the thermobalance. A solid solution uranium-plutonium oxide O/M reference material was prepared by alloying the uranium and plutonium metals in a yttrium oxide crucible at 1200$sup 0$C and oxidizing with moist He at 250$sup 0$C. The individual and solid solution oxides were isothermally equilibrated with controlled oxygen potentials between 800 and 1300$sup 0$C and the equilibrated O/ M ratios calculated with corrections for impurities and buoyancy effects. Use of a reference oxygen potential of -100 kcal/mol to produce an O/M of 2.000 is confirmed by these results. However, because of the lengthy equilibration times required for all oxides, use of the O/M reference materials rather than a reference oxygen potential is recommended for O/M analysis methods calibrations. (auth)

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A variant of the maraging class of steels is proposed for application at 77$sup 0$K and below where a combination of very high strength and good toughness is required. The alloy has a composition of Fe-12Ni-4Co-2Mo-0.05Ti where low interstitial content. The as quenched and quenched and aged structures were completely martensitic with a prior austenitic grain size of 10 to 12 $mu$m. This structure had a Y.S. of 138.5 ksi and 154 ksi before and after aging respectively. All aging was done at 444$sup 0$C for 4 hours. The DBTT was shown to lie above 77$sup 0$K as measured by C/sub v/ testing. Based on dilatometric studies of the $alpha$ $Yields$ $gamma$ and $gamma$ $Yields$ $alpha$ transformation temperatures a cycling treatment consisting of reportedly heating to above the A/sub f/ temperature followed by a water quench was utilized to further reduce the prior $gamma$ grain size to approximately 4 to 6 $mu$m. The structure was completely martensitic and possessed a Y.S. of 151 ksi at 77$sup 0$K in the unaged condition with a Y.S./K/sub IC/ ratio of 1.9 while the aged structure showed a Y.S. of 162 ksi with a Y.S./K/sub IC/ ratio of 1.3. C/sub v/ testing showed the …