Use of the Chebyshev-Legendre quadrature set in discrete-ordinate codes

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5958402

Walters, W F

The Chebyshev-Legendre (C-L) quadrature set has been implemented in the neutron transport section of the TWODANT code. The C-L quadrature set has two advantages as compared to other quadrature sets. First, it is possible to easily generate S/sub N/ orders up to S/sub 100/ with weights that are positive. TWODANT has been used to carry out calculations with as many as 10,000 discrete directions with the C-L quadrature set. Second, a product C-L set or order N will integrate exactly all the terms in the scattering source arising from P/sub N-1/ scattering. For example, the S/sub 4/ set will correctly integrate all scattering source terms if a P/sub 3/ scattering approximation is used. In TWODANT, users normally use the current S/sub 8/ quadrature set in the belief that P/sub 3/ scattering will be treated correctly. The S/sub 8/ set consists of some 40 directions and many times results in problem models that require excessive computer memory. The C-L S/sub 4/ set integrates exactly all the source terms associated with a P/sub 3/ expansion and consists of only 16 discrete directions. The results of test calculations, using both the current set and the C-L set in TWODANT, indicate that when high-order scattering is not significant, the two sets give answers that are in good agreement. 3 refs.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5958402
• Report Number(s): LA-UR-87-3621; CONF-8702113-1; ON: DE88001803
• Country of Publication: United States
• Language: English

Related Subjects

654003* -- Radiation & Shielding Physics-- Neutron Interactions with Matter
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
99 GENERAL AND MISCELLANEOUS
990230 -- Mathematics & Mathematical Models-- (1987-1989)
AMPLITUDES
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
EQUATIONS
FUNCTIONS
INTEGRAL EQUATIONS
LEGENDRE POLYNOMIALS
NEUTRAL-PARTICLE TRANSPORT
NEUTRON TRANSPORT
NUMERICAL SOLUTION
POLYNOMIALS
QUADRATURES
RADIATION TRANSPORT
SCATTERING AMPLITUDES
SPHERICAL HARMONICS