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  1. Fuel Programming in Pool-Type Research Reactors of Intermediate Power Level

    Hill, Ernest E. ; Shon, Frederick J. - Nuclear Science and Engineering
    Here, a fuel cycle program is presented for an intermediate power research reactor utilizing fully enriched MTR-type fuel elements. The fuel cycle program is considered at equilibrium after many cycles have past. The program consists of shifting elements from positions of high importance outward to positions of low importance through several paths. The paths are staggered so that only the elements in one path are shifted at the conclusion of a cycle, and only one element is replaced. The method of calculating the fuel remaining in each element is shown utilizing a fractional burn-up factor for each position. Sample calculationsmore » are shown for the LPTR with 23 standard elements in the core and a desired burn-up of 15%. A method is proposed to obtain such an equilibrium condition starting with an initial loading of fuel elements having nearly equal fuel loading.« less

  2. Spectral response to ground displacement at Hattiesburg resulting from nuclear event SALMON

    Blume, John A. - Bulletin of the Seismological Society of America
    Spectral response is developed from principal portions of a record of ground displacement in Hattiesburg, Mississippi, resulting from the SALMON event, Project DRIBBLE, an underground nuclear explosion near Baxterville, Mississippi in October 1964. Further, no acceleration records are available for Hattiesburg. As a part of the study it was found that peak response in the important short-period range could be reasonably estimated using as little as one second of selected motion from the entire record, and that a simple stochastic model of this key portion of the ground motion essentially duplicated the peak response.

  3. Performance of packed columns. II. Wetted and effective‐interfacial areas, gas ‐ and liquid‐phase mass transfer rates

    Shulman, H. L. ; Ullrich, C. F. ; Proulx, A. Z. ; ... - AIChE Journal
    AbstractA study was made of separating the volumetric mass transfer coefficients, kGa and kLa, into their components kG, kL, and a so that the effects of variables might be determined separately for each component. Mass transfer rates for four packings, 1/2‐ and 1 1/2‐in. Raschig rings and 1/2‐in. and 1‐in. Berl saddles, made of naphthalene, were determined by vaporization into air at gas rates from 100 to 1,000 1b./(hr.) (sq. ft.).The correlation for kGa was used to determine the wetted areas of those packings when irrigated with water and to calculate the effective interfacial areas, a, from Fellinger's data formore » ammonia absorption. These effective areas were then used to evaluate kL from previously published kLa data, and a correlation was obtained for all packings.The correlations for kGa and kLand the effective‐interfacial‐area data make possible a more rigorous method for the design of packed columns than was heretofore available.« less

  4. Performance of packed columns. I. Total, static, and operating holdups

    Shulman, H. L. ; Ullrich, C. F. ; Wells, N. - AIChE Journal
    AbstractTotal and static holdups have been measured for 1/2‐, and 1‐in. ceramic Berl saddles, 1/2‐, 1‐, and 1 1/2‐in. ceramic Raschig rings, and 1‐in. carbon Raschig rings with air rates from 100 to 1,000 1b./(hr.) (sq. ft.) and water rates from 1,000 to 10,000 1b./ (hr.) (sq. ft.).The holdup measurements and motion picture observations of the flow of dye solutions through packings provide an explanation for the great differences observed when gas‐phase mass transfer rates are measured by absorption and vaporization methods. If the effective interfacial area for vaporization is assumed to be proportional to total holdup and the areamore » for absorption is assumed proportional to operating holdup, the raio of the two mass transfer rates should be equal to the ratio of the two holdups.The departure from equality of the two ratios can be explained by the observation that the static holdup is displaced slowly, resulting in additional effective area for absorption over that expected from the operating holdup alone.« less

  5. Performance of packed columns. III. Holdup for aqueous and nonaqueous systems

    Shulman, H. L. ; Ullrich, C. F. ; Wells, N. ; ... - AIChE Journal
    AbstractTotal, static, and operating holdups have been measured for 1‐in porcelain and carbon Raschig rings and 1‐in. porcelain Berl saddles, employing aqueous solutions of calcium chloride, sorbitol, and a wetting agent as well as pure methanol and benzene. The range of variables covered by this investigation includes liquid rate, 1,000 to 10,000 1b./(hr.) (sq. ft.); viscosity, 0.6 to 185 cp.; surface tension, 23 to 86 dynes/cm.; specific gravity, 0.8 to 1.32.Equations and charts are presented for estimating holdups for all liquids. The application of holdups for estimating mass transfer coefficients, kG, and effective interfacial areas, a, is discussed.The total holdupsmore » for water, methanol, and benzene can be used to explain why mass transfer coefficients obtained by vaporization of pure liquids in packings seem to depend on gas diffusivity raised to the 0.15 power instead of the 0.67 power, as found in other mass transfer studies. The larger total holdups of nonaqueous liquids result in larger effective interfacial areas in the packing, which mask the effect of the change in gas diffusivity.« less

  6. Some fundamental ideas in topology and their application to problems in metallurgy

    Barrett, Lida K. ; Yust, C. S. - Scripta Metallurgica
    The topological ideas and results that have been used by metallurgists, together with several results not previously presented in the metallurgical literature, are developed in a systematic manner. Based on this presentation, a review is given of the use of topology in metallurgy. The additional topology that is introduced includes the Alexander duality theorem, the Euler-Poincare formula, and the concept of deformation retract. Further, these concepts are used to establish interrelationships among the results of several papers and to clarify the mathematical treatment.

  7. Precision studies of duality in the ’t Hooft model

    Lebed, Richard F. ; Uraltsev, Nikolai G. - Physical Review. D, Particles Fields
    Here we address the numerical aspects of local quark-hadron duality using the example of the exactly solvable ’t Hooft model, two-dimensional QCD with Nc →∞. The primary focus of these studies is the total semileptonic decay widths relevant for extracting |Vcb| and |Vub|. We compare the exact channel-by-channel sum of exclusive modes to the corresponding rates obtained in the standard 1/mQ expansion arising from the operator product expansion. An impressive agreement sets in unexpectedly early, immediately after the threshold for the first hadronic excitation in the final state. Yet even at higher energy release it is possible to discern themore » seeds of duality-violating oscillations. We find the “small velocity” sum rules to be exceptionally well saturated already by the first excited state. We also obtain a convincing degree of duality in the differential distributions and in an analogue of Re+⁢e–(s). Finally, we discuss possible lessons for semileptonic decays of actual heavy quarks in QCD.« less

  8. Perturbation Techniques for Models of Bursting Electrical Activity in Pancreatic $$\beta $$-Cells

    Pernarowski, M. ; Miura, R. M. ; Kevorkian, J. - SIAM Journal of Applied Mathematics
    Pancreatic β-cells exhibit periodic bursting electrical activity consisting of active and silent phases. Experimentally, the ratio, ρf, of the active phase duration to the overall period is correlated to the insulin response of these cells to glucose concentration. Several different mathematical models of the β-cell have been developed to describe changes in the intracellular ionic concentrations and the ionic flow through the cellular membrane. The membrane potential in each of these models exhibits the same active and silent phase bursting patterns observed experimentally and, therefore, these models can be used to predict the value of the plateau fraction, ρf. Themore » Sherman-Rinzel-Keizer (SRK) model of this phenomenon consists of three coupled first-order nonlinear differential equations which describe the dynamics of the membrane potential, the activation parameter for the voltage-gated potassium channel, and the intracellular calcium concentration. These equations are transformed into a Lienard differential equation coupled to a single first-order differential equation for the slowly changing nondimensional calcium concentration. Leading-order perturbation problems for the silent phase and the transition regions are reduced to quadrature. The solution of the leading-order active phase problem is a limit cycle which depends on the value of the intracellular calcium concentration. Since the active phase equations exhibit weak damping, Melnikov's method can be applied to determine the bifurcation point of these equations. Thus, an explicit expression for the active phase duration is obtained. Together with the silent phase analysis, an approximation of the plateau fraction, ρf, is derived and its value compared to the plateau fraction numerically obtained from the SRK model.« less

  9. Validity of the model used to relate the energy distribution and the adsorption isotherm

    Roles, Jeffry ; Guiochon, Georges - Journal of Chromatography
    The reproducibility and accuracy of the determination of the adsorption energy distribution for a probe compound on a solid surface is discussed. This distribution can be calculated from the adsorption isotherm, itself derived from the chromatographic profiles of high concentration bands, using the elution by characteristic points method. Further, distributions derived from experimental data acquired under different experimental conditions agree well within the limits of the reproducibility of these data. Band profiles calculated from the adsorption energy distribution are also in excellent agreement with those recorded.

  10. Numerical simulation of tokamak electron dynamics

    Miner, W. H. ; Winsor, N. K. ; Bernstein, I. B. - Physics of Fluids (New York)
    In a tokamak, the electron distribution deviates from a Maxwellian because magnetically untrapped electrons run away parallel to the applied electric field. A new method for calculating the dynamics of the electron distribution is presented. This method is novel because it can treat systems with comparable numbers of trapped and untrapped electrons, and an electric field comparable with (but smaller than) the Dreicer field. The electron distribution function and the plasma resistivity are presented for representative values.
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