Analytic angular integration technique for generating multigroup transfer matrices

Conference · Sun Jan 01 04:00:00 EST 1978

OSTI ID:7180133

Bucholz, J. A.

Many detailed multigroup transport calculations require group-to-group Legendre transfer coefficients to represent scattering processes in various nuclides. These (fine-group) constants must first be generated from the basic data. An alternative technique for generating such data from the total scattering cross section of a particular nuclide on a pointwise energy basis, sigma(E'), and some information regarding the angular scattering distribution for each initial energy point is outlined. The evaluation of generalized multigroup transfer matrices for transport calculations requires a double integration extending over the primary and secondary energy groups, where, for a given initial energy, the integration over the secondary energy group may be replaced by an integral over the possible scattering angles. In the present work, analytic expressions for these angular integrals are derived which are free of truncation error. Differences between the present method (as implemented in ROLAIDS) and other methods (as implemented in MINX and NEWXLACS) are explored. Of particular interest is the fact that, for hydrogen, the angular integration is shown to simplify to the point that, for many weight functions, the integration over the primary energy group might also be performed analytically. This completely analytic treatment for hydrogen has recently been implemented in NEWXLACS. 1 figure.

• Research Organization: Oak Ridge National Lab., Tenn. (USA)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7180133
• Report Number(s): CONF-780329--1
• Country of Publication: United States
• Language: English

Related Subjects

654003* -- Radiation & Shielding Physics-- Neutron Interactions with Matter
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
COMPUTER CODES
INTEGRALS
MULTIGROUP THEORY
NEUTRON TRANSPORT THEORY
R CODES
TRANSPORT THEORY