摘要:

AbstractA calorimeter has been built whereby the amounts of power dissipated in each of three units are made equal. The power due to the interaction of a unit with gammas, and that due to interaction with neutrons, is determined from the electric power supplied to each unit and known parameters of the system. Three units composed of two materials are necessary and sufficient for this type of measurement.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18136

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractA study of five methods of determining burnup in fuel test specimens has been made to determine the confidence which can be placed in the burnup numbers so obtained. The five methods compared are (1) uranium-235 depletion, (2) cobalt monitoring, (3) cesium-137 production, (4) plutonium production, and (5) calorimetry. The study includes a comparison of data obtained on portions of the specimen with that obtained on the complete specimen. It has been found that all of the methods give burnup values that are within±5% of the“best”burnup value, the“best”value being defined as the unweighted average of all the available results on a particular sample. The limitations and pitfalls of all the methods are discussed in some detail. It has further been found that a complete cross-section of the test specimen, approximatelyin. long, is sufficient sample to give representative burnup data. The integration from this to the complete specimen is relatively straightforward. Any sample not comprising a complete cross-section involves radial as well as longitudinal integration, giving results that are relatively uncertain, particularly in samples of high heat rating where migration of some species is a distinct possibility.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18137

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractTitanium and titanium alloys are not generally resistant to mercury in the temperature range between 371 to 538 C. The extent of corrosion is dependent upon alloy composition and heat treatment. Nitrided surfaces of titanium and its alloys exhibit high resistance to mercury at 538 C for periods up to 14 days. At this temperature, mercury vapor attacks certain nitrided alloys while others are immune. For instance, the corrosion of a nitrided Ti/8wt% alloy was found to be insignificant; however, severe corrosion occurs at the nitrided layer of Ti/7wt% Al/12wt% Zr.aA study of the effect of metallic additives to mercury on the corrosion resistance of titanium at 538 C has also been made. It has been shown that a saturated mercury solution of zirconium or nickel exerts a strong influence in reducing corrosion. The films formed may act as a diffusion barrier between solid and liquid.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18138

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractThe results of a systematic qualitative and quantitative study of the little understood phenomenon of fatigue in photomultiplier tubes are presented in this paper. A precision of 0.4% was obtained in the measurements. After having determined the variables that affect fatigue and the mathematical dependence of fatigue with each of them, the general properties of fatigue and the nature and mechanism of the effect are discussed. Photomultiplier fatigue appears as a field emission from the dynode bombardment, probably combined with diffusion or conductivity through the thin insulator film of the dynode surface.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18139

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractTheoretical methods for computing intracell thermal-neutron densities, disadvantage factors and thermal utilizations are presented. The topics discussed are the computation of the neutron spectra in a lattice, anisotropic scattering by water, the cylindrical cell effect, correlation of spectral moments and average one-group cross sections, one-group transport-theory methods, scattering models of water, and comparison of various theories with experiment. The lattices investigated are water moderated with slightly enriched uranium metal and oxide fuel.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18140

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractIn support of the High Flux Isotope Reactor Program, experimental determinations were made of friction factors, burnout heat fluxes, and average and local nonboiling heat-transfer coefficients for forced-convection flow of water through thin aluminum and nickel rectangular channels under the following conditions: heat flux = 0.1×106to 7.4×106Btu/h·ft2, velocity = 10 to 85 ft/sec, Reynolds number = 9,000 to 270,000, pressure = 1 to 39 atmospheres absolute, flow gap = 0.043 to 0.057 in., and heated length = 12 and 18 in. A few tests were made to ascertain the effect of an axially oriented cylindrical spacer strip on surface-temperature distribution and burnout heat flux. The results of these studies, unlike those of some earlier investigations of narrow-gap heat transfer, are in reasonably good agreement with accepted correlations. The friction factors are in satisfactory agreement with the Moody chart for the relative roughness of the test sections used, the burnout heat fluxes are well reproduced by the Soviet Zenkevich-Subbotin correlation, and the local and average heat-transfer coefficients are slightly larger than values predicted by the Hausen and Sieder-Tate equations.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18141

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractTwenty-nine experimental determinations of burnout heat flux were made with water flowing by natural circulation through electrically heated vertical tubes with and without internal twisted tapes and through rectangular cross sections of three aspect ratios. Heated lengths varied from 10 to 33 in., system pressure at the test-section flow exit from 14.7 to 26.3 lb/in.2abs, inlet subcooling from 36 to 170 F, and burnout heat flux from 13,000 to 218,500 Btu/h·ft2. Tests were made with both unrestricted and restricted return flow paths. Three correlations were developed for predicting natural-circulation burnout heat fluxes for such conditions. Two are useful for rapid estimation, but the third involves a more fundamental assessment of the coolant-mass velocity at burnout by a graphical matching of the heat flux which a given flow rate can sustain to the heat flux which will produce that flow rate. For all the data, this approach gave average and maximum deviations of 15% and 38%, respectively. It has been found that use of a slip ratio of unity is adequate for burnout prediction, and the reasons for this are discussed in detail. The small burnout penalty incurred by a substantial restriction of return flow path, experimentally observed, is in accord with the theoretical model.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18142

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractCalculations of the ionization density resulting fromβ-ray fluxes produced by the decay of UX2(Pa234m) using constant-cross-section transport theory agree with experiment to better than 5%. The ionization densities were measured using an extrapolation chamber and a thin-walled ionization chamber. The experimentalβ-ray absorption coefficients reported in 1931 by the International Radium-Standards Commission can be calculated to better than 15% using the same theory.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18143

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractGas chromatography was used for qualitative and quantitative determination of the products of the hydrolysis of uranium carbides and of thorium carbides. The products were separated on four columns: 5A molecular seive, di-2-ethylhexyl sebacate, tricresyl phosphate, and silica gel modified with squalane. The hydrocarbons were identified by use of known gaseous and liquid alkanes, alkenes, and alkynes. The numerical data were obtained by IBM 7090 computation.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18144

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor

摘要:

AbstractThe reaction O17(n, p) and the previously unreported reaction O18(n, d)were found to be responsible for the production of the 4.14-second delayed-neutron precursor, nitrogen-17, in water irradiated in a reactor. The effective cross sections of these reactions with fission-spectrum neutrons were measured by counting the delayed neutron emission of irradiated water samples enriched with oxygen-17 and -18. The values obtained are 7.4±0.6 and 0.086±0.008µbrespectively.

ISSN:0029-5639    

DOI:10.13182/NSE64-A18145

出版商:Taylor&Francis    

年代:1964

数据来源: Taylor