摘要:

AbstractThe normal mode expansion technique is applied to the transformed mono-energetic integral transport equation to develop a solution for the rotationally invariant and axially infinite critical two-region cylinder with a finite outer reflector boundary. The model assumes isotropic scattering and identical neutron mean-free-paths in the core and reflector regions. The solution in terms of singular integral equations is obtained by applying a completeness theorem found for the singular eigenfunctions. Numerical results for a variety of core and reflector multiplying properties and reflector thicknesses are presented and compared with the results of other methods. The completeness inherent in this solution and the high precision in the numerical calculations provide results which may be used as analytic standards for this problem.112

ISSN:0029-5639    

DOI:10.13182/NSE73-A23285

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractTo date, most of the work done using the response matrix technique has involved one-dimensional slab problems. In this paper, the method is applied to two-dimensional slab problems and the results are compared with Monte Carlo calculations. It was found that the error due to the numerical treatment of the spatial distribution could be substantial. However, various corrections based on physical arguments were found which significantly improved the results.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23286

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractYields and spectra of neutrons produced in the bombardment of light nuclei by deuterons of energies up to 20 MeV were measured in order to investigate the usefulness of the reactions as high-intensity neutron sources. Neutrons emitted at angles up to 32 deg were studied for thin targets of deuterium and beryllium, and for thick targets of lithium, beryllium, and carbon.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23287

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractSimultaneous measurements of the neutron fission and capture cross sections of235U have been performed at the Oak Ridge Electron Linear Accelerator for neutrons with energies between 8 eV and 10 keV. These cross sections were measured relative to the shape of the standard10B(n,α) reaction cross section, and normalized to the Oak Ridge National Laboratory-Rensselaer Polytechnic Institute data between 100 and 200 eV.The comparison of the present235U capture cross section with the values from other available sources shows that below 200 eV there is general agreement within an error band of±5%. In the keV energy region, the average difference observed rises to±12%.The fission cross-section results presented here agree with a worldwide compilation of fission data typically within a 3% error in the entire range of neutron energies investigated in this work.The values of alpha, capture-to-fission ratio, exhibit a remarkable amount of structure.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23288

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractA series of criticality experiments have been completed with plutonium nitrate solutions made up from extremely high burnup fuel (239Pu isotopic concentration<½total Pu). The measurements were performed on a large, 61-cm-diam, water-reflected, cylindrical vessel. The critical experiment data were analyzed by means of the KENO Monte Carlo code utilizing both ENDF/B-H and -III cross sections; the computed criticality factors were in the range of 1.6 to 1.9% above unity. The effects of the various heavy element isotopes on criticality were analyzed. The results show the importance of properly accounting for, and treating, the effects of each of the various isotopes in computing criticality. Even the presence of as little as 1% of241Am can cause a change in the reactivity of the solutions used in these experiments by∼1%.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23289

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractA simple method of nonlinear filtering is applied to the problem of dynamic reactivity estimation in which the law of reactivity change is assumed to be unknown. The filter is designed based on a system model containing the usual point reactor kinetics equations driven by fictitious white noises and a reactivity state equation. The latter is formulated such that the rate of the reactivity change is a random process, taking account of the unknown reactivity change. The nonlinear filter applied here is a simple modification of the Kalman filter added with a nonlinear feedback loop. The key parameter that determines the filter response is the parameter of the fictitious noise in the reactivity equation which is closely related to the filter gain. The results of the computer simulation and the experiment show that the nonlinear filter can be used to estimate the dynamic reactivity, even under an extremely noisy measurement condition.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23290

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractAn iterative optimization method based on linearization and linear programming is developed. The method can be used for the determination of the material distributions in a fast reactor which maximize or minimize integral reactor parameters that are linear functions of the neutron flux and the material volume fractions.The method has been applied to the problems of optimization of the fuel distribution in a reactor of fixed power output, constrained power density, and constrained material volume fractions so as to obtain (a) a maximum initial breeding gain, (b) a minimum critical mass, and (c) a minimum sodium void reactivity. Under this realistic set of constraints, numerical results show that the same fuel distribution yields maximum breeding gain, minimum critical mass, minimum sodium void reactivity, and uniform power density.

ISSN:0029-5639    

DOI:10.13182/NSE73-3

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractA formalism is developed for full exploitation of a gas tag system used for locating failed fuel elements in fast reactors. Based on the measured gas tag ratios detected in an actual failure, the method assigns quantitative probabilities to the various combinations of failures which can occur. Both the failure of a single fuel element and the simultaneous failure of two elements are treated in detail.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23292

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractThe effect of streamwise heat conduction on heat transfer from a flat plate is studied at low Prandtl numbers. The surface temperature of the plate is assumed to vary according to a power law with the longitudinal distance. The analysis is performed as a perturbation of the classical boundary-layer theory. The resulting similar energy equations are solved for small Prandtl number by using the method of matched asymptotic expansions.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23293

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor

摘要:

AbstractBuildup factors for gamma rays traversing slab shields have been obtained using the Monte Carlo method. Secondary particles produced inside the shield were taken into account, with special attention given to the contribution of bremsstrahlung which is produced by electrons and positrons. The results indicate that annihilation gamma rays from pair production do increase the buildup factor a little, but that the bremsstrahlung contribution is much more pronounced. The contribution of bremsstrahlung to the dose buildup factor reaches 33% of its total value for 8-MeV gamma rays traversing 5 mean-free-paths of lead.For single-material shields, the results agree well with the experiment. For double-material shields, comparison with experiment is not possible due to the lack of such data.

ISSN:0029-5639    

DOI:10.13182/NSE73-A23294

出版商:Taylor&Francis    

年代:1973

数据来源: Taylor