摘要:

AbstractA surface perturbation method to determine reactivities is described which has application to the removal of reflectors, the lowering of water levels in reactors, the introduction of voided beam tubes, the insertion of black control rods, etc. A first-order approximation, using the unperturbed flux in the calculations, is shown to be in error for large perturbations. However, a simple one-energy expression is devised for the shape rather than the magnitude of the reactivity curve, that successfully predicts relative effects. The method is compared with an experimental determination of the reactivity worth of the variable upper reflector of the MITR.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25754

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA transparent plastic in which gas was formed by gamma irradiation, was used to investigate the mechanisms of gas bubble formation and growth. Bubble formation and swelling were studied for several environments, both external and internal to the plastic-gas systems. During irradiation at 100°C, larger, but fewer bubbles form in the plastic than on lower temperature irradiation followed by 100°C annealing. The data indicate that inclusions increase bubble formation and internal surfaces promote bubble growth.An interpretation of these results, when applied to nuclear fuel swelling, indicates that swelling may be decreased by increasing fission rate and by decreasing the available sites for bubble nucleation and growth.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25755

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe production of flat thermal flux by the nonuniform distribution of the moderator is discussed within the framework of two group theory for two region reactors. Equations determining the moderator distribution are derived and a numerical solution is presented for a typical reactor system. The moderator density is found to increase with increasing distance from the center of the core. All combinations of core and reflector materials cannot be used in these flat flux systems, and the restrictions which determine allowability are discussed. In the special case of slab reactors in which the core and reflector are the same materials these systems have minimum critical mass.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25756

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe total cross section of Lu176was measured over the range of neutron energies from 0.02 to 0.25 ev. The data were taken with a sample enriched to 70.2% in Lu176. The resonance at 0.142 ev in Lu176was fitted to a Breit-Wigner single-level formula by the method of shape analysis. Parameters are presented for computing the activation cross section as a function of neutron energy over the region of measurement.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25757

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe application of heavily loaded cylindrical fuel elements to two principal reactor configurations is considered. The objective of the work is the design of research reactors suitable for radiation effects studies.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25758

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe effect of fission on circulating a UO2-NaK suspension has been studied up to a total uranium burnup of 0.07%. A loop of one-half inch stainless steel tubing with a test volume of 250 cc was irradiated in the Argonne CP-5 reactor. The loop contained 5% vol. (40% wt) 93.14% enriched UO2suspended in NaK alloy and was operated for 902 hr at temperatures above 350°C. No difficulty was encountered during the operation of the loop in the reactor. Examination of the slurry after irradiation showed extensive comminution of the UO2particles. Analytical results after termination of the experiment revealed the distribution of some fission products. 45.5% of the krypton and xenon fission gases were found in the cover gas. 82% of the cesium was found dissolved in the NaK. Cerium and zirconium were found with the UO2.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25759

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractAs part of the Yankee and the Belgian Reactor-3 Critical Experiments program at the Westinghouse Reactor Evaluation Center, measurements have been made of the parameters leading top, f, andϵin a light-water moderated heterogeneous reactor with slightly enriched UO2fuel rods clad in stainless steel. A detailed description of this reactor is given in reference 1. Measurements were made using 4.48% and 2.73% enriched fuel with lattice pitches of 0.470 and 0.435 in. The individual UO2sintered pellets, in the fuel rods, had a diameter of 0.300 in. and a length of 0.600 in. The 4.48% and 2.73% fuel rods contained 90 and 80 pellets, respectively. The stainless steel cladding was 0.305 in. i.d. and 0.347 in. o.d. for the 4.48% enriched fuel, and 0.306 in. i.d. and 0.338 in. o.d. in the case of 2.73% enrichment. The measurements were performed using a higher fuel enrichment than used previously at Bettis (2, 3) and elsewhere for similar experiments, thus uncovering a large unexplored range of enrichments.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25760

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe results of an extensive study of the relative velocity of two-phase mixtures at ANL are presented. The parameter ranges studied are pressure 150–2000 psi, mixture quality 0–0.25, superficial liquid velocity 0.5–8 ft/sec, and flow channel equivalent diameters of 0.4–2 in. The data were correlated by means of the velocity ratio (steam velocity/liquid velocity) which was calculated from the measured steam volume fraction. The steam volume fraction measurements were made by a radiation attenuation technique and the data were obtained from both adiabatic and nonadiabatic systems.The data show that the velocity ratio is affected primarily by pressure, mixture quality, superficial velocity, and to a lesser degree by the flow channel geometry. The data are also compared with the data of other investigators for the vertical up-flow of steam-water mixtures.Working curves for the prediction of the velocity ratio are then presented which are adequate for system analyses. The working curves are given for 150, 250, 400, and 600 psi. A method of extrapolating the data for predicting working curves in the high-pressure range is suggested.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25761

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA novel formulation of the problem of boundedness and stability of the power level of a nuclear reactor describable by a nonlinear model is presented. A sufficient criterion for boundedness and stability is derived and proved to be equivalent to the criterion suggested by Welton. The criterion is illustrated by means of two examples.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25762

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractCalculations are made of the infinite multiplication factor in natural uranium dioxide lattices employing mixtures of light and heavy water as a moderator. The three parameters varied in the study are (a) the metal-to-water volume ratio, (b) pin diameter, and (c) light-to-heavy water atomic ratio. Maxima in plots of K∞vs hydrogen-to-deuterium ratio indicate that such H2O + D2O mixtures would prove advantageous in certain cases. However, in these cases, slight fuel enrichment might be required.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25763

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor