Fundamental mode decay constants for small two- and three-dimensional pulsed neutron moderator assemblies

Journal Article · Mon Dec 01 04:00:00 EST 1980 · Nucl. Sci. Eng.; (United States)

OSTI ID:7156590

Kumar, V; Sahni, D C

A method has been developed to calculate the fundamental mode decay constants in two- and three-dimensional pulsed neutron moderator assemblies using the separable form of the scattering kernel in the transport equation. The method uses the Fourier transform of the integral transport equation and is an extension of the method developed by Sahni to treat monoenergetic criticality problems for two- and three-dimensional geometries. The new kernel of the integral transform equation is factored into components depending on only one of the dimensions of the assembly. This property is further exploited by use of a single Fourier mode approximation in one or more dimensions while the kernels in the remaining dimensions are retained in their respective forms. In the author's numerical work, three simple forms of the scattering cross section are used for calculating the matrix elements of the relevant equations accurately. Numerical results are presented for the asymptotic decay constant in a one-dimensional slab, a one-dimensional cylinder, two-dimensional infinite rectangular prisms, and three finite cylinders of different height-to-diameter ratios. The relation between the asymptotic decay constant and the geometrical buckling in the transport and diffusion approximations are also calculated for interpreting the results in terms of extrapolation lengths.

• Research Organization: Bhabha Atomic Research Centre, Theoretical Reactor Physics Section Bombay 400 085
• OSTI ID: 7156590
• Journal Information: Nucl. Sci. Eng.; (United States), Journal Name: Nucl. Sci. Eng.; (United States) Vol. 76:3; ISSN NSENA
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220100* -- Nuclear Reactor Technology-- Theory & Calculation
ASYMPTOTIC SOLUTIONS
BUCKLING
CROSS SECTIONS
DECAY
DIMENSIONS
EQUATIONS
EXTRAPOLATION LENGTH
FOURIER TRANSFORMATION
FUNDAMENTAL CONSTANTS
GEOMETRIC BUCKLING
INTEGRAL EQUATIONS
INTEGRAL TRANSFORMATIONS
KERNELS
LENGTH
MATRIX ELEMENTS
MODERATORS
NEUTRON TRANSPORT THEORY
ONE-DIMENSIONAL CALCULATIONS
PULSED NEUTRON TECHNIQUES
SCATTERING
THREE-DIMENSIONAL CALCULATIONS
TRANSFORMATIONS
TRANSPORT THEORY
TWO-DIMENSIONAL CALCULATIONS