Computation of higher spherical harmonics moments of the angular flux for neutron transport problems in spherical geometry

The integral form of one-speed, spherically symmetric neutron transport equ ation with isotropic scattering is considered. Two standard problems are so lved using normal mode expansion technique. The expansion coefficients are obtained by solving their singular integral equations. It is shown that the se expansion coefficients provide a representation of all spherical harmoni cs moments of the angular flux as a superposition of Bessel functions. It i s seen that large errors occur in the computation of higher moments unless we take certain precautions. The reasons for this phenomenon are explained. They throw some light on the failure of spherical harmonics method in trea ting spherical geometry problems as observed by Aronsson. (C) 2000 Elsevier Science Ltd. All rights reserved.