摘要:

AbstractA new conceptual design of a fusion reactor blanket simulation facility has been developed. This design follows the principles that have been successfully employed in the Purdue Fast Breeder Blanket Facility (FBBF), where experiments have resulted in the discovery of substantial deficiencies in neutronics predictions. With this design, discrepancies between calculation and experimental data can be nearly fully attributed to calculation methods because design deficiencies that could affect results are insignificant. The conceptual design of this FBBF analog, the Fusion Reactor Blanket Facility, is presented. Essential features are the cylindrical geometry and a distributed line source of 14-MeV neutrons with a cosine-shaped intensity distribution. The source design consists of a deuteron beam sweeping over an elongated titanium-tritide target. To predict the character of the neutron flux this source will produce, neutronics analyses were performed. Predictions for two- and one-dimensional calculations are compared for two blanket compositions. Expected deviations from one-dimensional predictions, which are due to source anisotropy and blanket asymmetry, are shown to be minimal. Therefore, one-dimensional calculations can be performed in fine detail as a basis for the generation of accurate coarse group constants for two-dimensional predictions. The proposed design of this fusion blanket facility should allow straightforward interpretation of experimental results in terms of computational and data deficiencies.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23500

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractAn investigation of the potential behavior of large amplitude nuclear-coupled density-wave oscillations in a boiling water reactor (BWR) was performed. A simplified, nonlinear BWR core model was developed and used to predict the growth of oscillations as a limit cycle is approached. For high-power/low-flow initial conditions, large density-wave oscillations could cause periodic pulses in core power. The fuel temperature, which rapidly increases at high-power conditions and slowly recovers, is considered as the fast variable in a relaxation oscillation. With an appropriate transformation of the system equations, the approximate limit cycle trajectory can therefore be determined using singular perturbation analysis. In the first approximation, where the relaxation is assumed to occur infinitely fast, the phase-space trajectory combines the slow part with an instantaneous jump between end points to form a closed cycle. The accuracy of this approximation is improved with appropriate perturbation series expansions on both the slow and fast parts, as well as introduction of a separate expansion for the connections between these parts. The approximate solution is considerably simpler to obtain than a conventional numerical solution of the original equations.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23501

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractBy making use of the Laplace transform technique, time-dependent first-flight leakage rates from slabs, spherical shells, and spheres with a uniform source distribution and a delta-shaped pulse have been calculated from their steady-state counterparts found in the available literature. Time-dependent solutions for a quadratic source distribution with a delta pulse have been obtained for a slab and a solid sphere. Using the results for a slab and a solid sphere with a uniform source as a Green’s function, the case of a constant source emitting neutrons over a time intervalΔt is considered.

ISSN:0029-5639    

DOI:10.13182/NSE97-203

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractA simple mathematical model is presented to depict the filtration mechanism of crud or colloidal particles in the ion exchange resin bed. In this model the filtration process is classified into four stages, corresponding to the increase in the deposited amounts of the particles on the surfaces of the resins during the filtration process. In the first stage, it is assumed that the adhesion of crud particles is mainly controlled by the electrokinetic interaction between the particle and the virgin surfaces of the resins, while in the third stage the crud particles interact with the particles already adsorbed on the resins. The second stage is a transient period between the first and third stages. In the final stage, the clogging effect becomes significant. At the first stage of filtration, the model explains the rapid decrease of filtration efficiency, which is a matter of great concern from the practical point of view. A comparison is made between the model and laboratory experiments, using monodispersedα-Fe2O3particles as model crud, and it is found that the proposed mechanism of filtration process seems quite reasonable.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23503

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractAngular neutron fluxes leaking from the surface of beryllium slab assemblies have been measured with irradiation of deuterium-tritium neutrons. The experiment was performed using the time-of-flight technique with an NE-213 scintillation detector. The measured neutron energy range was from 50 keV to 15 MeV. The thicknesses of the slabs were 50.8 and 152.4 mm, and the measured angles of the angular fluxes were 0.0, 12.2, 24.9, 41.8, and 66.8 deg. The experimental results have been compared with the results calculated by the Monte Carlo codes, MORSE-DD and MCNP, using the data of beryllium in the JENDL-3PR1, ENDF/B-IV, and Los Alamos National Laboratory nuclear data files. The results calculated with these files showed discrepancies of 20 to 30% from the experimental results. It was pointed out that the angular distributions of an elastic cross section and the total cross section of an inelastic reaction for 14.8-MeV neutrons in the files were insufficient to reproduce the measured spectra.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23504

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe prompt fission neutron spectrum resulting from239Pu fission induced by∼0.55-MeV incident neutrons is measured from 1.0 to 10.0 MeV relative to that of235U fission induced by the same incident energy neutrons. The measurements employ the time-of-flight technique. Energy-dependent ratios of the two spectra are deduced from the measured values. The experimentally derived ratio results are compared with those calculated from ENDF/B-V (revision 2) and with results of recent microscopic measurements. Using the ENDF/B-V235U Watt parameters for the235U spectrum, the experimental measurements imply a ratio of average fission spectrum energies of239Pu/235U = 1.045±0.003, compared to the value 1.046 calculated from ENDF/B-V (revision 2).

ISSN:0029-5639    

DOI:10.13182/NSE87-A23505

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractThe neutron capture cross section of elemental rhenium was measured to neutron energies between 3 and 1900 keV at the Oak Ridge Electron Linear Accelerator time-of-flight facility. A deformed optical model was used to analyze published neutron total cross sections for rhenium and low-energy average resonance parameters for185Re and187Re. The optical model results were used with reaction theory to calculate radiative capture cross sections for comparison with the present experimental data.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23506

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractStratified sampling is a method used in Monte Carlo calculations to take advantage of certain known aspects of probability distributions. The sampling region is subdivided into discrete subregions, and each of these is sampled a preassigned number of times. A form of stratified sampling has been implemented into a major Monte Carlo particle transport computer code with very encouraging results.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23507

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

摘要:

AbstractA general acceleration scheme for the iterative transport calculations is analyzed, and the implementation of this scheme in the two-dimensional transport code TWOTRAN PNWV is described.The convergence radius is estimated for homogenous one-dimensional slab problems. Two-dimensional benchmark problems are used to outline the dependence of the convergence on the material properties and on the fine- and coarse-mesh grids.Possible applications of this scheme to obtain acceleration methods for other iterative algorithms are suggested.

ISSN:0029-5639    

DOI:10.13182/NSE87-A23508

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE87-A23509

出版商:Taylor&Francis    

年代:1987

数据来源: Taylor