The Multi-PN angular discretization method of the neutral-particle transport equation for radiation shielding calculations. (November 2022)

• Record Type: Journal Article
• Authors: Falabino, Matteo; Sciannandrone, Daniele; Masiello, Emiliano; Vidal, Jean-François
• Is Part Of: Annals of nuclear energy. Volume 177(2022)
• Publication Date: 2022-11
• Subjects: Neutron transport -- Radiation shielding calculations -- Ray-effect mitigation -- IDT solver; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2022.109301
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Multi-P N method effectively mitigates ray-effect in radiation shielding problems. Multi-P N method relies on a piecewise–polynomial expansion of interface angular fluxes. Multi-P N is applied within the short characteristic discretization of the IDT solver. Abstract: The well-known Discrete Ordinates (S N ) approximation is little effective in multidimensional radiation shielding calculations. In the presence of geometrically large and low-scattering media, discrete-ordinates solutions are generally affected by the ray effect and an adequate refinement of the angular discretization is sometimes prohibitive in terms of calculation cost. The Multi-P N method (MP N ) is an angular discretization technique leading to S N -like transport equations but less affected by ray effect. It relies on a solid angle expansion of the interface fluxes, allowing for a local coupling between different angular degrees of freedom within the same solid angle. This coupling enables to solve the equation by means of a standard sweeping algorithm. Furthermore, flux angular moments are directly integrated without any use of quadrature rules. The MP N measured error convergence rate with respect to the number of angular degrees of freedom is significantly larger than the one measured with S N .