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[en] The existence of certain reciprocity-like relations in neutron transport theory was shown earlier under some quite restrictive conditions. Here, these relations are shown to be valid in more general situations by using a different approach based on individual neutron trajectories. (author)
[en] An adaption is presented to an earlier method for the prediction of time-eigenvalues of the neutron transport equation. Instead of using the full-parity first-order equation, the algorithm uses the even-parity formalism in the most expensive part of the computations resulting in a more economic method
[en] Highlights: •A modified α − k power iteration method is presented for computing the time-eigenvalue. •It is not required to provide the initial values of α for the modified method. •Computational experiences validate the validity and efficiency of the new method. -- Abstract: A modified α − k power iteration method is presented for the prediction of time-eigenvalue(α) of the neutron transport equation. By developing a direct relationship between K-eigenvalue and α-eigenvalue, a new formula is introduced to estimate the value of α. Compared with the conventional method, it is not required to provide the initial values of α for the modified method. Since it is always difficult to guess the suitable initial values, the modified method is more convenient for solving time-eigenvalue problems. Computational experiences show that the accuracy of the modified method is the same as the conventional method.
[en] The present lecture is a continuation of the lecture on Introduction to the Neutron Transport Phenomena. It comprises three aspects of lattice calculations. First the idea of a reactor lattice is introduced. Then the main definitions used in reactor lattice analysis are given, and finally two basic methods applied for solution of the transport equations are defined. Several remarks on secondary results from lattice transport calculations are added. (author)
[en] We are interested in the solution of the Multigroup Neutron Transport Equation. After the presentation of the multigroup treatment, the angular, time and space discretization, we expose the modifications that have been made in order to get an efficient parallel method. (author)
[en] Under the assumption of isotropic scattering, the simplified spherical harmonics method (SPN) was recently formulated in variational nodal form and implemented successfully as an option of the VARIANT code. In this paper, we remove the isotopic scattering restriction. The variational nodal form of the SPN approximation is formulated and implemented with both within-group and group-to-group anisotropic scattering. Results are presented for a model problem previously utilized with the standard PN variational nodal method
[en] The idea of importance sampling is applied to the problem of solving integral equations of Fredholm's type. Especially Bolzmann's neutron transport equation is taken into consideration. For the solution of the latter equation, an importance sampling technique is derived from some simple transformations at the original transport equation into a similar equation. Examples of transformations are given, which have been used with great success in practice
[en] Systematic measurements were carried out on the possible use of elastically backscattered Pu-Be neutrons combined with the thermal neutron reflection method for the identification of land mines and illicit drugs via he detection of H, C, N, and O elements as their major constituents. While ur present results show that these methods are capable of indicating the anomalies in bulky materials and observation of the major elements, e termination of the exact atom fractions needs further investigation.
[en] The 3-D steady-state SN neutron-gamma transport theory code ATES3 developed at BARC can be utilized for external source problems such as shielding analysis. A brief description on the use of ATES3 and its validation for international shielding type benchmarks problems is presented in the paper. (author)
[en] The PN approximation to the neutron transport equation has been well established for decades. Gelbard et al. have proposed the FLIP formulation of the planar PN equations, consisting of a system of coupled diffusion equations that is solved by a certain iterative procedure. Gelbard has also proposed the SPN approximation to the multidimensional spherical harmonics equations. This approximation can be obtained by an asymptotic expansion of the transport equation or (in an ad hoc manner) by replacing the one-dimensional Laplacian operators in the planar geometry FLIP equations by three-dimensional Laplacian operators. The FLIP iteration strategy for the planar geometry PN equations can be directly applied to the SPN equations. This iteration strategy has been the basis of many SPN methodologies examined to date