Condições de contorno tipo albedo para cálculos globais de reatores nucleares com o modelo de dois grupos de energia na formulação de transporte SN em geometria bidimensional cartesiana

• Autor(a) principal: Nunes, Carlos Eduardo de Araújo
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/13689
• topic: Computational modeling; Albedo boundary conditions; Neutral particle transport; Discrete ordinates; Criticality calculations; Teoria cinética do transporte Método das ordenadas discretas; Nêutrons Transporte Métodos de simulação; Partículas (Física nuclear) Transporte Métodos de simulação; Modelagem computacional determinística; Condições de contorno tipo Albedo; Transporte de partículas neutras; Ordenadas discretas; Cálculos de criticalidade; CNPQ::ENGENHARIAS::ENGENHARIA NUCLEAR::TECNOLOGIA DOS REATORES

As neutron fission events do not take place in the non-multiplying regions of nuclear reactors, e.g., moderator, reflector, and structural components, these regions do not generate power and the computational efficiency of nuclear reactor global calculations can hence be improved by eliminating the explicit numerical calculations within the non-multiplying regions around the active domain. Discussed here is the computational efficiency of approximate discrete ordinates (SN) albedo boundary conditions for two-energy group eigenvalue problems in X,Y geometry. Albedo, the Latin word for whiteness , was originally defined as the fraction of incident light reflected diffusely by a surface. This Latin word has remained the usual scientific term in astronomy, and in this thesis, this concept is extended for the reflection of neutrons. The non-standard SN albedo substitutes approximately the non-multiplying regions around the active domain, as we neglect the transverse leakage terms within these non-multiplying regions. Should the problem have no transverse leakage terms, i.e., one-dimensional slab geometry, then the offered albedo boundary conditions are exact. By computational efficiency we mean analyzing the accuracy of the numerical results versus the CPU computing time of each run for a given model problem. Numerical results to two ¼ symmetric test problems are shown to illustrate this efficiency analysis.