Angular finite element techniques in neutron transport

The possibility, by the use of angular finite elements, of reducing ray effects deeply rooted within the angular discretization techniques adopted to solve the neutron transport equation, is analysed. Such a reduction can be foreseen on purely physical grounds by considering the diffusive wave form assumed by the equations of the discrete model. Particular consideration is given to 2D problems, for which it is shown that, in general, it is possible to cast the finite element equations into a formal SN form. This enables well tested numerical methodologies, devised for finite differences SN in more sophisticated finite elements applications, to be exploited. Some explicit cases are then discussed, using simple angular element shape functions, and a few numerical results of reference calculations are presented. (author)