摘要:

AbstractFlow patterns that occur in a rod bundle with forced upward flow of boiling water have been photographed. The experimental rod bundle consisted of four vertical 0.25-in.-diam×24.0-in. long rods arranged in a single row with spring collar supports. The tested conditions were: pressure—400 to 2000 psia, mass velocity—250 000 to 3 000 000 lb/h-ft2, and heat flux (uniform)—up to 1 600 000 Btu/h·ft2. The observed two-phase flow patterns were bubble flow, froth flow, slug flow, and annular flow. These flow patterns were mapped at constant pressure on plots of mass velocity versus flowing quality.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27286

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractThe common features used in the measurement6Li(n,α),10B(n,αγ), and235U(n,f) cross sections presented in three subsequent papers are described. The experiments were performed on the 200-m flight path of the National Bureau of Standards Linac and cover the neutron energy region from 5 to 800 keV. The neutron flux monitor was a hydrogen-filled gas proportional counter located at the end of the flight path, while the primary detectors specific to each of the three cross-section measurements were placed 70 m along the flight path. The properties of the neutron source, the detailed operation of the flux monitor, the data acquisition system, and the data analysis procedure are described. The systematic errors in the neutron flux measurement are given.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27287

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractThe shape of the6Li(n,α)T cross-section curve has been measured from 3- to 800-keV neutron energy. The neutrons were produced by the National Bureau of Standards 140-MeV Linac, and the measurements were made along the 200-m above-ground drift tube. The neutron flux was monitored by a 61-cm-long hydrogen gas proportional counter giving a direct ratio of the6Li(n,α) cross section to the H(n,p) cross section. The6Li(n,α) events were detected in a 0.5-mm-thick piece of6Li glass (NE-912). The results were normalized to ENDF/B-V in the region from 10 to 100 keV. Overall uncertainties in the measurement are∼2% in the range from 10 to 400 keV. Error analysis and comparisons with previous measurements are given.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27288

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractThe10B(n,αγ)7Li relative cross section has been measured using the 200-m flight path of the National Bureau of Standards Linac neutron time-of-flight facility. Results are presented from 5 to 700 keV, showing the 5/2-level of11B at 500 keV.The neutron flux was monitored with a hydrogen proportional counter. The known n-p scattering cross section was then used to normalize the data to obtain a relative cross section. No attempt was made to obtain an absolute normalization experimentally. Overall accuracy is estimated to be better than 3% from 10 to 400 keV.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27289

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractMeasurements of the absolute neutron fission cross sections of235U,238U, and239Pu have been made at 13.9 and 14.6 MeV with a double 4πionization chamber. The associated particle method with the time-of-flight technique was used. Our final values ofσnf(235U),σnf(238U),σnf(239Pu),σnf(238U)/σnf(235U), andσnf(239Pu)/σnf(235U) are compared to previous data.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27290

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractThe purpose of this work is to investigate the applicability of the discrete-ordinates (SN) method to light ion sputtering problems. In particular, the neutral particle discrete-ordinates computer code, ANISN, is used to calculate sputtering yields. No modifications to this code are necessary to treat charged particle transport. However, a cross-section processing code is needed for the generation of multigroup cross sections; these cross sections include a modifi

ISSN:0029-5639    

DOI:10.13182/NSE78-A27291

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractDerivations are given of the equations for the dose rate laterally from a cylindrical source in terms of the integral functions ofŌno and Tsuruo, as expressed by the compact functions of Shure and Wallace, and including the buildup in the form of Taylor coefficients.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27292

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractThe method of elementary solutions, the CNmethod, and the integral transform method are used to compute the flux-distortion factor for a foil placed in an exponentially varying flux.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27293

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractA theoretical analysis of the reactivities of experimentally measured uniform light-water-moderated and -reflected PuO2in UO2lattices and Pu(NO3)4solutions is presented here. The mixed-oxide single-rod lattices are homogenized by the use of multigroup integral transport theory, and diffusion theory is used for the cylindrical core calculations. The cross sections are derived from the WIMS library. The homogeneous spherical Pu(NO3)4solutions are analyzed by discrete-ordinates transport theory. Due to the small size of these assemblies, it is necessary that one-dimensional core calculations also be performed with a cross-section energy-group structure that can accurately represent neutron slowing down and thermalization at the core-reflector interface. Due to the uncertainty present in the Battelle Northwest Laboratories analyses of the mixed-oxide lattices, the agreement of our predictions for these lattices with measurement is considered to be more satisfactory. Our reactivity predictions agree generally within +0.6% of measurements for the mixed-oxide lattices and within 1% for the solution systems.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27294

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor

摘要:

AbstractTwo-group calculations of the propagation of neutron waves across an absorption discontinuity in beryllium are reported. The first slab is assumed to be of finite width, while the second is taken to be of infinite dimensions. It is found that in the first slab, the effect of the interface is felt earlier for lower frequencies.

ISSN:0029-5639    

DOI:10.13182/NSE78-A27295

出版商:Taylor&Francis    

年代:1978

数据来源: Taylor