摘要:

AbstractThe kinetic characteristics of muon-catalyzed deuterium-tritium (D-T) fission processes are considered. Rate equations for the dominant muonic and nonmuonic reactions are formulated and the associated particle densities determined as a function of time. Parametric expressions intended to provide an indication of the energetic viability of muon-aided fusion reactions are formulated and evaluated. It appears that muon-catalyzed D-T fusion at low temperature does possess the potential of energy gain under certain experimental conditions.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21409

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThe l’th Legendre component of the multigroup transfer matrix,σlg→j, is developed for the general nonrelativistic two-body interaction-arbitrary (nonzero) particle masses and reaction Q value. This theory furnishes the necessary particle interaction, i.e., scattering, and particle production matrices for coupled particle-particle transport calculations.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21410

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThrough a direct statistical approach, analytic expressions are derived for the second moment, the variance ratio, and benefit functions of a model for n-surface geometric splitting. The model is general in that it can be applied to many geometric and material conditions, energy dependence, and biasing methods besides splitting. The model applies to any detector, provided that the detector region is separated from the source region. The model has the following limitations: (a) every source particle reaching the detector must cross all splitting surfaces, (b) particles are allowed to split only once on each surface, (c) weight-dependent biasing schemes are not included, and (d) reactions that bifurcate the particle are excluded.The derived expressions depend linearly on n unknown constants that are bulk properties of the medium in a given problem. These constants may be estimated approximately from one small sample run invoking the point-surface approximation or from (n + 1) consecutive small sample runs.Numerical examples are given in verification of the theory, and the possibility of using the expressions in an in-code optimization or self-optimizing code is discussed.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21411

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThe fundamental problems encountered in any attempt to include a description of the production and transport of monoenergetic (discrete) radiation in a continuous-energy adjoint Monte Carlo procedure are explored. An idealized, one-dimensional, double-scattering transmission problem is employed in order to devise a method for overcoming these difficulties. This method is then generalized to an adjoint Monte Carlo procedure for describing coupled continuum/discrete radiation transport.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21412

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractNeutron or radiation transport kernels in general have two factors, namely, the space transition part and the energy-angle transition part. Importance biasing schemes are obtained here for these two factors separately leading to zero variance estimation by Monte Carlo. These biasing schemes are different from the one obtained by straightforward extension of importance biasing of the transport kernel. New biasing schemes are obtained for collision, track-length, and expectation estimators. Using the moments equations developed by Amster and Djomehri and extended by Lux to treat nonanalog games it is shown that these new biasing schemes lead to zero variance in the Monte Carlo estimation of reaction rate type of quantities.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21413

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractA number of investigators have discussed the use of two-detector cross power spectral density (CPSD) measurements to obtain the velocity of an axially propagating perturbation of the moderator density in a boiling water reactor. The basis of the measurements is the view that the detector response can be separated into local and global components where the local component, which is dominant for high frequencies (f>2 Hz), makes possible the observation of the moving perturbation associated with steam flow in the reactor. For low frequencies, the response consists of a combination of the local and global components, and correlation with the perturbation velocity is not straightforward.In this Note, the asymptotic low and high frequency behavior of the CPSD is examined using the complex detector adjoint function formulation. It is shown that at low frequencies, where the wavelength of the perturbation is much larger than the axial core dimension, the phase of the CPSD and therefore the perturbation velocity correlates with the centroid spacing of detector functions involving the product of the detector adjoint function and the static flux. For high frequencies, on the other hand, the phase correlates with the detector spacing. This behavior is considered to be an alternate manifestation of the local/global concept. Numerical calculations based on a two-group, one-dimensional model are used to illustrate these observations. It is also shown using the model that the oscillations in the phase in the intermediate frequency range disappear for frequencies that correspond to wavelengths that are intergral multiples of the core height.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21414

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractTo improve the isotope exchange reaction efficiency between water and hydrogen, a new reactor in which water mists and hydrogen gas react cocurrently was studied. To apply this to the enrichment of tritium in heavy water, a dual temperature isotope exchange reactor which is composed of cocurrent low temperature reactors and the usual countercurrent high temperature reactor was proposed and analyzed using a McCabe-Thiele diagram. By utilizing cocurrent reactors, in combination, the necessary catalyst volume can be reduced to one-tenth as compared with the usual countercurrent low temperature reactor.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21415

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractThe neutron capture yield in two232Th samples (0.0008 and 0.0027 atom/b, respectively) was measured with the Oak Ridge Electron Linear Accelerator time-of-flight facility over incident neutron energies from 100 to 4000 eV. A detailed comparison of the measured capture yields with calculations based on ENDF/B-V resonance parameters suggests that above 500 eV the evaluation needs additional work; in particular, the average capture appears systematically underestimated.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21416

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

摘要:

AbstractA procedure is described for removing two error vectors from the approximation to the solution obtained iteratively. Such a scheme for accelerating convergence can reduce the computation cost of solving neutronics problems as is demonstrated for finite difference diffusion theory.

ISSN:0029-5639    

DOI:10.13182/NSE82-A21417

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE82-A21418

出版商:Taylor&Francis    

年代:1982

数据来源: Taylor