摘要:

AbstractThe ratio of the damage rates in graphite irradiated in the converter and VT-4 of CP-3′are explained in terms of the different flux spectra which existed in the respective irradiation facilities. This interpretation requires that the statistical quantity of damage resulting from a scattering event involving a neutron of given energy be nearly constant above 105ev, and this in turn implies that the statistical amount of damage produced by a carbon atom of given energy is nearly constant above 104ev and is in agreement with Seitz's theory. Good agreement is found between the rate at which disturbances in the lattice are accumulated and the rate of carbon atom displacement calculated from Seitz's theory, but this is not considered especially significant since the parameters had originally been adjusted to fit experimental data.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25381

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractData obtained from three systems are presented and discussed in reference to the problem of radioactive carry-over in boiling reactors. Measurements of droplet carry-over have been made on a small scale laboratory boiling test unit and on a 600-psia loop under high purity water conditions using Cs137tracer. Measurements have also been made on the Borax-III boiling reactor under actual operating conditions. Activation products present in the steam and condensate served as an indication of the radioactive carry-over. Analysis of the decay curves of the samples provided a means of differentiating activities carried as droplets from volatile radioactive carry-over.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25382

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractThe attenuation of 14.1-Mev neutrons in water has been studied under conditions simulating an isotropic point source of monoenergetic neutrons in an infinite water medium. The migration area of thermal neutrons (〈r2〉th/6) was found to be 156±6 cm2. The“age”of indium resonance neutrons was measured to be 150±6 cm2. Fast neutron dose measurements are in agreement with the theoretical calculations of Goldsteinet al.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25383

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractRecent experiments have indicated that some organic materials such as diphenyl may be sufficiently resistant to radiation damage to perform satisfactorily as coolants for nuclear reactors. These materials offer such advantages as low vapor pressure at high temperatures, lack of induced radioactivity, and low corrosion attack on fuel and structural materials. A collection of data on vapor pressure, density, specific heat, viscosity, thermal conductivity, and heat transfer film coefficient for diphenyl is presented as an aid to the reactor designer. Some experimental data on melting points and viscosities of mixtures of diphenyl with higher polyphenyls are also given.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25384

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractThe thermal neutron flux in a water medium from a source disk containing water irradiated in the Materials Testing Reactor has been measured using a BF3detector. Neutrons from N17and photoneutrons from N16gamma rays have been observed. The radial distribution of thermal neutrons from an isotropic point source of N17neutrons in a water medium out to 35 cm has been deduced, and has been compared with a theoretical calculation of the distribution based on Holte's values of the collision density at 1 ev from a point isotropic source of 1-Mev neutrons. From the results of this experiment and Holte's distribution, the square of the diffusion length plus the age from 1 ev to thermal energies, has been calculated to be 8.2 cm2. This value is in reasonable agreement with previously reported measured values.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25385

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractLocal heat transfer coefficients were measured in a circular, copper tube of inner diameter 0.25 in., outer diameter 0.55 in., and length 36 in. Direct resistance heating of the tube wall from a direct current power source dictated the size and material of the test section. Since the electrical resistivity of copper varies appreciably with temperature, the radial heat flux was nonuniform along the length. (The temperature drop across the tube wall was small; therefore the heat flux in the radial direction was assumed uniform.) The test section was cooled from the inside with the eutectic alloy of sodium and potassium (22% Na, 78% K) flowing turbulently in a vertical direction.The range of variables covered in the experiment was as follows : fluid temperature from 85°to 1175°F, fluid velocity 4 to 60 ft/sec, Reynolds number 13,000 to 466,000, Peclet number 268 to 3850, average heat flux 28,600 to 3,200,000 Btu/(hr ft2). The maximum local heat flux was 6,000,000 Btu/(hr ft2).For the above test conditions the experimentally measured Nusselt numbers ranged from 1.4 at the low Peclet number to 22.4 at the high Peclet number. Most of the fully-developed Nusselt numbers found are lower than indicated by the Lyon-Martinelli equation, but are in quite good agreement with data of most other experimenters. The values of Nusselt number in the entrance region are about 40% higher than those predicted by Deissler, and approximately 10% higher than the data of Johnson, Hartnett, and Clabaugh. Near a Peclet number of 300, the Nusselt numbers observed were lower, by a factor of more than two, than the theoretical minimum for fully developed laminar flow. The reason for this abnormality has not been established.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25386

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractThe energy distribution of neutrons thermalized in an infinite homogeneous medium containing a crystalline moderator and absorbing material is investigated with the aid of a simplified model of the crystal. A Debye phonon spectrum is assumed, and a formal expansion in powers of the ratio of neutron mass to moderator atom mass is used. The inelastic scattering is approximated by the term of first order in the mass ratio, and interference effects are neglected. The resulting energy-change kernel is not correct in detail at high energies, but it correctly gives the average logarithmic energy loss, and therefore can be used in the age theory approximation at energies well above thermal. Solutions of the integral equation for the energy spectrum have been obtained on the IBM-650 for (1/υ) absorption. These are compared to solutions of the differential equation for a heavy gaseous moderator. It is found that the thermal spectra are very insensitive to the choice of scattering model, even when large departures from thermal equilibrium occur.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25387

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

摘要:

AbstractEquations for the thermal stresses developed in clad, flat, fuel plates with either symmetrical or nonsymmetrical temperature distribution are presented. The stresses developed under one set of conditions are calculated and shown as an application of the equations.

ISSN:0029-5639    

DOI:10.13182/NSE57-A25388

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE57-A25389

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE57-A25390

出版商:Taylor&Francis    

年代:1957

数据来源: Taylor