摘要:

Studies have been made of the electrophoretic behavior of various samples of plutonia and thoria. Significant differences were observed between samples of the same compound having a different history, but general common trends were apparent. Differences in behavior between plutonia and thoria were no greater than those between different samples of either compound.Adsorption isotherms were calculated using a standard model of the double layer. The data suggest that both plutonia and thoria surfaces adsorb multivalent cations much more readily than monovalent ones. Anions are adsorbed to a varying degree, with the notable exception of nitrate. Both hydrogen and hydroxyl ions significantly affect the surface charge density. The adsorption isotherms do not obey a simple Langmuir law.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26473

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

Data obtained from studies of the electrophoretic mobility of thoria and plutonia suspensions have been examined in relation to their dispersion and ion adsorption properties. Dispersion data in many cases bear out qualitatively the concept of a critical zeta potential below which flocculation of the suspension takes place, but exceptions to the rule have been found in a number of electrolyte solutions. Adsorption isotherms obtained from tracer studies and direct analysis have been compared with those calculated from electrophoretic data. Differences betweenζandψin the case of hydrogen ions are qualitatively consistent with adsorption on a negative site in the presence of a Stern-type layer of anions. Observations with I−,, Cs+, Sr2+, Ce3+, and Th4+require a qualified interpretation, and reveal the danger of drawing quantitative conclusions from electrophoretic data unsupported by more direct measurements.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26474

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

A generalized least squares technique has been used to calculate equilibrium constants and their variation with medium in solvent extraction equilibria by minimizing the difference between observed and calculated distribution ratios. The model involved a Debye-Hückel term for low and a linear term for high ionic concentration corrections (i.e., activity coefficient changes) in the aqueous phase, consistent with current semitheoretical treatments. In the organic phase either no correction or a linear term in volume % TBP was found adequate to about 20 vol. % TBP. The method involved the evaluation of the assumed parameters in the least squares sense while iteratively correcting for ionic strength changes with varying (calculated) ionic concentrations. Due to imprecision of the data and to convergence difficulties encountered in nonlinear procedures, it was not feasible to evaluate as many parameters as desired, and hence the model had to be oversimplified in some cases. Nevertheless, the method has been successfully applied to the extraction of uranyl nitrate and nitric acid by TBP dissolved in an inert diluent. It is suggested that with sufficiently precise and consistent data the method is capable of evaluating all the equilibrium parameters involved in relatively complex extraction systems.A series of computer programs has been written in an attempt to calculate distribution ratios in relatively complex solvent extraction systems. The general procedure involved setting up equilibrium expressions and determining the parameters by a generalized least squares technique. The present paper describes calculations on the distribution of UO2(NO3)2and HNO3between an aqueous phase and an organic phase consisting of tributyl phosphate (TBP) dissolved in an inert diluent (Amsco 125-90W).1Since it was desired to keep the model simple and since convergence difficulties were encountered when the model was made more realistically elaborate, the assumed equilibria do not necessarily involve all species which may have been shown to exist in some of the solutions in question (e.g., UO2NO3+and UO2(NO3)2).

ISSN:0029-5639    

DOI:10.13182/NSE63-A26475

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

Local convective heat transfer coefficients for a surface with integral boundary-layer turbulence promoters were determined by conducting naphthalene-to-air mass transfer tests and invoking the heat transfer-mass transfer analogy. The turbulence promoters were machined into the convex surface of an annulus. The experimental results were normalized relative to mass transfer coefficients on a smooth surface with parallel flow.On the faces of the turbulence promoters local heat transfer coefficients up to six times the smooth surface value were encountered. High transfer coefficients were found on the upstream and top faces. Coefficient values on the downstream surfaces were low and independent of geometry. Corner areas showed heat transfer coefficients lower than those for a smooth surface with parallel flow.The data from surfaces between two turbulence promoters were correlated in terms of a dimensionless location index. A broad heat transfer coefficient peak of 2.4 times the smooth surface magnitude was found 4 turbulence promoter heights downstream from a promoter. Each test also showed a narrow coefficient peak at the point about 0.5 height preceding a turbulence promoter. When correlated in this manner, the results revealed a unique generalized distribution of the transfer coefficient for surfaces with boundary layer turbulence promoters of rectangular cross section. The upstream and downstream regions of boundary layer separation were independent of the dimensions of the turbulence promoters.The estimated error for this series of tests was approximately±20 % of the maximum relative transfer coefficient values.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26476

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

Relative reaction rates have been measured in the fuel and moderator of a CANDU-type lattice cell and analyzed to obtain the spectrum parameters, i.e., effective neutron temperatureTand epithermal index. Measurements were made with the coolant channels containing the normal heavy water and also light water and mixtures of light and heavy water at temperatures up to 280°C. An empirical formula has been derived for the effective neutron temperature in the fuel of operating power reactors with similar fuel geometries.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26477

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

The slowing-down spectrum in a CANDU-type reactor cell has been studied using resonance activation techniques. The measurements covered the energy range 1.46 ev to 367 ev. The effects of replacing the heavy water coolant with mixtures of light and heavy water and light water were studied. Measurements were also made in a channel without fuel clusters.The spectra observed in the normal cell were approximately 1/Ethroughout the cell except for depressions caused by prominent U238resonances. With no fuel in the cell, large departures from 1/Ewere observed.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26478

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

Relative reaction rates in selected nuclides have been measured through the central lattice cell of ZEEP with the fuel cluster replaced by a pressure tube containing different mixtures of light and heavy water. The surrounding heavy water moderator was at room temperature. Measurements were made with the pressure tube filled with air and four mixtures ranging from reactor grade heavy water to light water, at temperatures up to 280°C.The radial variations are given for the reaction rates, which were measured, and for the effective neutron temperatureTand the epithermal index, deduced from the reaction rates.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26479

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

The method of singular eigenfunctions introduced first by Van Kampen and developed later by Case and Mika in connection with a one-velocity transport problem, has been adapted in order to solve the time and energy dependent infinite medium problem. The expansion of neutron density and scattering kernel in series of Hermite functions reduces the Boltzmann equation to a system of homogeneous linear equations. The resulting set of regular and singular eigenfunctions is shown to be complete (ifw∑nonelasticis assumed to increase monotonically with the neutron velocityw) and explicit formulas are found for the normalization integrals and Green's function.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26480

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

In estimating flux at a point in a Monte Carlo calculation one estimator uses the uncollided flux at a detector from each sampled collision point. This method is shown to have infinite variance. The average value converges to the expected value but the error decreases asymptotically as the inverse cube root of the number of histories. By using the once collided flux and by proper choice of the intermediate collision point the variance may be made finite. Results of numerical experiments show the finite variance methods to be preferable.

ISSN:0029-5639    

DOI:10.13182/NSE63-A26481

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

A numerical program is described for calculating the probability distribution of neutrons or delayed neutron precursors in a multiplying assembly. The program obtains the probability distribution generating function, from which the distribution itself is found by inversion of a Laplace transform. Six groups of delayed neutrons may be used. The prompt neutron lifetime is arbitrary and neutron source and reactivity may be functions of time. The existence of an asymptotic probability distribution at late times is proved for constant reactivity. Six group results are shown to be in good agreement with experimental data from Godiva.

ISSN:0029-5639    

DOI:10.13182/NSE63-2

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor