摘要:

AbstractA process, developed at Oak Ridge National Laboratory, produced thorium metal by the continuous reduction of anhydrous thorium tetrachloride with sodium amalgam on a scale up to 3.5 pounds per hour. The salt was vigorously agitated with an excess of sodium amalgam which was produced by the electrolysis of aqueous sodium hydroxide. The resulting slurry of thorium mercuride in mercury was washed free from impurities and reaction by-products with dilute HCl and water. A solid concentrate of the thorium mercuride was prepared by filter-pressing the dilute slurry. The remaining mercury was removed by vacuum-distillation, resulting in massive metal of about 0.8 of the theoretical thorium density. The metal was fabricated into rods by direct extrusion or by arc-melting followed by extrusion.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28827

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractMeasurements have been made to determine the effect of mutual shielding on the resonance absorption of neutrons by tightly packed thorium oxide lattice pins. From these measurements, correction factors have been obtained for reducing the results of single-pin resonance integral measurements to the effective lattice values. A comparison of the experimental results with the predictions of the theory of Dancoff and Ginsburg is included.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28828

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractThe relative reactivity worth of several B10F3gaseous coupons has been determined at pressures up to 4.2 atmospheres. These worth values are compared with equivalent B10loading as B4C dispersed (100 mesh or less) in stainless steel. Gaseous boron is more than five times as effective as the dispersed boron due to particle self-shielding. Bulk self-shielding becomes important only at high concentrations. The gaseous coupons are also compared with two alloy coupons (normal B10and enriched B10).

ISSN:0029-5639    

DOI:10.13182/NSE58-A28829

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractThe gamma-ray dose rate and the fast neutron flux have been measured in air from a source of water shortly after irradiation in the Materials Testing Reactor. Gamma rays from N16and neutrons from N17have been detected. From the measurements and the known geometry, the cross sections for the O16(n,p) N16and the O17(n,p) N17reactions averaged over the fission neutron spectrum have been deduced to be 0.019 mb and 0.0052 mb, respectively. The results are compared with other measured values and theoretical estimates.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28830

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractThe average 1.44-ev indium resonance age has been determined from activation measurements for a D(d,n) He3neutron source in water. The energy of the incident deuteron beam was 250 kev. The source emits neutrons anisotropically with energies from 3.12 Mev at 0°to 2.00 Mev at 180°. The activities were averaged over angle by the Gauss integration procedure using angles of 20.3°, 90°, and 159.7°. The average age, when corrected for the absence of moderator in the duct which brings the deuteron beam into the medium, is 34.6±2.2 cm2. Rigorous theoretical calculations for a D+D neutron source by Zweifel give 33.6 cm2for 100-kev incident deuterons and 33.8 cm2for 150-kev deuterons. Any estimate of an age for a 250 kev D+source would yield a larger value of age and closer agreement with this experiment. The variation of our measured agesversusangle may be understood qualitatively on the basis of effects due to the duct and the anisotropy of the source. A more precise theoretical check of this experiment is expscted when Monte Carlo calculations now in progress for precisely our geometry and source become available.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28831

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractThe method for computing absolute thermal neutron flux from measurements made with activated indium foils is described. By combining data from the counting rate of indium foils in 2πproportional counters with appropriate corrections for foil weights and neutron effects, the thermal flux is expressed in terms ofσO, the thermal absorption cross section of In115. This procedure may be used by laboratories which do not have access to a standard graphite pile or to a standard neutron source. This method has an estimated error of less than 5% which is a function of the accuracy with which it is possible to determine the various correction factors for beta counting. A possible fixed error in the value ofσOcan easily be corrected for and incorporated into the methods used.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28832

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractThe slowing down of neutrons by a monoatomic moderator gas with temperature can be expressed by a variational formalism. Using a suitable trial solution one can calculate the effective neutron temperature and the upper limit of the thermal region by variation. Results are given for large moderator masses and small absorption.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28833

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractThe total neutron cross sections of several structural materials have been measured over the thermal range of energy. A plate of commercial wrought nickel, thin sheets of 61,S aluminum and a cylinder of 2Saluminum of 3-in. diameter were studied. The results of the measurements are compared with previous results and the observed differences are interpreted in terms of crystal structure.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28834

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractIn this paper the solution of the neutron transport (Boltzmann) equation in plane and spherical geometries is considered. It is demonstrated that the method of discrete ordinates differs from the spherical harmonic method merely by a linear transformation (with constant coefficients) of the dependent variables.

ISSN:0029-5639    

DOI:10.13182/NSE58-A28835

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

AbstractVarious methods of approximating the kinetics of circulating fuel reactors are investigated. As the basis for comparison, a relatively“exact”model is used, predicated on perfect mixing in the core and slug flow in the external loop. The derivations and applicability of the various approximate methods are presented. It is shown that the frequency response of the“exact”model can exhibit peaking (i.e., resonances). The effect of such peaking on the transient response of the system is illustrated. The possibility of self-sustained oscillations of reactor power, resulting from the feedback caused by delayed neutron precursors re-entering the core, is also discussed.

ISSN:0029-5639    

DOI:10.13182/NSE4-588-597

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor