Title: Comparative study of random and uniform models for the coated fuel particles distribution in pebble bed reactors

Authors: Jesús Alberto Rosales García; Carlos R. García Hernández; Carlos A. Brayner De Oliveira Lira; Jesús Pérez Curbelo; Amaury Muñoz Oliva; Dany Sánchez Domínguez

Addresses: Instituto Superior de Tecnologías y Ciencias Aplicadas (InSTEC), Av. Salvador Allende y Luaces, La Habana, 10400, Cuba ' Instituto Superior de Tecnologías y Ciencias Aplicadas (InSTEC), Av. Salvador Allende y Luaces, La Habana, 10400, Cuba ' Departamento de Energía Nuclear, Universidade Federal de Pernambuco (UFPE), Av. Luiz Freire 1000, Cid. Universitaria, Recife, Brazil ' Instituto Superior de Tecnologías y Ciencias Aplicadas (InSTEC), Av. Salvador Allende y Luaces, La Habana, 10400, Cuba ' Instituto Superior de Tecnologías y Ciencias Aplicadas (InSTEC), Av. Salvador Allende y Luaces, La Habana, 10400, Cuba ' Programa de Pós-graduação em Modelagem Computacional, Universidade Estadual de Santa Cruz, Ilhéus, BA, Brazil

Abstract: The use of TRISO fuel is a main feature of the high temperature reactors. In these reactors, the heterogeneity in the internal composition of the TRISO particle and the random arrangement of coated fuel particles inside graphite matrix creates a significant challenge in the modelling tasks. To simulate spherical elements using MCNPX code repetitive structures are usually created, generating a uniform distribution of the coated fuel particles. The use of these repetitive structures introduces two major limitations: the no randomness of the TRISO particles inside the pebbles and the intersection of the pebble surface with the particles. These limitations could affect significantly the multiplicative properties of the core. In order to study the influence of these approximations in the multiplicative properties of pebble-bed reactor cores, four different configurations for the TRISO particles distribution inside pebble were analysed. On pebble scale, the results showed significant differences between the models where the cutting effect is present and the model that treats the cutting effect. However, on core scale there are no differences among the results of the HTR-10 critical height for the studied models.

Keywords: TRISO particles; double heterogeneity; HTR-10; MCNPX; VHTR; modelling; coated fuel particles; particle distribution; pebble bed reactors; high temperature reactors; nuclear reactors; nuclear energy; nuclear power; simulation; rector core.

DOI: 10.1504/IJNEST.2016.076357

International Journal of Nuclear Energy Science and Technology, 2016 Vol.10 No.1, pp.72 - 87

Received: 04 Jan 2016
Accepted: 17 Mar 2016

Published online: 04 May 2016 *

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