摘要:

AbstractA systematic comparison has been made of the local difference operator approximation in spatial difference schemes for the solution of the transport equation in slab geometry by the method of discrete ordinates. The truncation error in different schemes varies according to the nature of the intra-mesh source and flux interpolation, and this explains the good performance of certain recently proposed schemes. We have classified the schemes according to the nature of the intra-mesh source interpolation. As a general principle, we find that in each class, the scheme that conserves the spatial moments of source calculated from the previous iteration and avoids flux interpolation is the most accurate.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19287

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractA generalization of the classical quasi-static method is described.“Amplitude”and“shape”functions are treated on the same footing by applying an iterative Newton method to the integral form of the multigroup diffusion equations. Provision is made for one amplitude function per neutron group. It is shown, further, how this model encompasses Ott and Meneley’s improved quasi-static algorithm.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19288

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractA new scattering kernel for heavy water has been proposed. The kernel takes into account the chemical binding energy effects and also includes the rotational and intramolecular vibrational modes. Using this scattering kernel, various neutron transport processes in the temperature range 5 to 60°C have been studied and compared with the corresponding experimental results. The calculated results include1.total neutron scattering cross section at 20°C2.asymptotic decay of neutron pulses in the temperature range 5 to 60°C and temperature variation of the diffusion coefficient and diffusion cooling coefficient3.time-dependent spectra inside finite-sized assemblies of heavy water at 20 and 43.3°C4.thermalization time5.diffusion length and space-dependent study in pure and poisoned assemblies of heavy water.The calculated results are in good agreement with the experimental results. At some places notable differences are observed between the results obtained using our scattering kernel and those based on the Honeck kernel.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19289

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractCross sections for the63Cu(n,α)60Co reaction have been measured by activation for neutron energies from threshold to 10 MeV relative to well-known238U fission cross sections. The data obtained are compared with values from the literature and the resulting spectrum-averaged cross sections based on the new results are given for the235U thermal fission and252Cf spontaneous fission neutron field. The new results indicate that the long-standing discrepancy between differential and integral data for the reaction63Cu(n,α)60Co has been eliminated.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19290

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractCross sections for the52Cr(n,p)52V reaction have been determined in the 5.3- to 9-MeV range using a previously reported pulsed-accelerator technique to measure gamma-ray activity from 3.75-m52V. Very few experimental data have been reported for this reaction, and little was known about the threshold region prior to the present experiment. The results of this work (in conjunction with other available cross-section information) have been used in the computation of fission-spectrum averages, which are of interest for reactor applications.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19291

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractThe effect of the source thickness in gated⊽measurements has been determined accurately. All existing⊽data for thermal fission of233U,235U,239Pu, and241Pu have been revised and a comparison is made with values of⊽derived from theηvalues.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19292

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractThe method of elementary solutions and the FNmethod are used to compute and report especially accurate numerical results relevant to a previously established four-region test problem in the theory of neutron diffusion.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19293

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractThe near-equilibrium energy spectrum of the delayed neutrons from the fast neutron-induced fission of240Pu has been measured over the energy range from 40 to 1500 keV. The spectrum is somewhat similar in shape to near-equilibrium spectra previously reported for other isotopes, and the peak structure is consistent with results from both fissionable isotopes and from various individual delayed neutron precursors.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19294

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractCross sections for the66Zn(n,p)66Cu reaction have been measured in the 4.2- to 10-MeV energy range using conventional activation techniques. This work provides results for an energy region where no other data are available. These results, and values from the literature for energies above 13 MeV, are used to provide an estimation of the cross-section excitation function from∼4.2 to 20 MeV. An extrapolation of the cross section from 4.2 MeV to the effective threshold at∼3 MeV is derived from calculations based on a semiempirical model that is fitted to the experimental data at higher energies. This excitation function is used to compute fission-spectrum-average cross sections, which are compared with corresponding values from the literature.

ISSN:0029-5639    

DOI:10.13182/NSE80-A19295

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

AbstractMonte Carlo calculations have been made for the penetration of slab shields by gamma radiation of monoenergetic character. The radiation is in the form of parallel, broad beams incident on the front face of the slab at various angles having cosines between 0.25 and 1.0. The beam photon energies vary between 0.661 and 6.13 MeV. The slab thicknesses extend to 10 mean-free-paths. The results are provided in the form of tables and graphs for exposure transmission buildup factors as a function of slab thicknesses. Comparison with previous work shows good agreement; however, this work goes somewhat beyond previous contributions.

ISSN:0029-5639    

DOI:10.13182/NSE80-2

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor