UO2 fuel pin bowing effects on isotopic concentrations

The effects of the fuel pin bowing are simulated in a 3 × 3 pin-cells lattice to assess the possible modeling biases on isotopic concentrations during depletion calculations. The central pin in the lattice is modeled with a deformation and as a function of burn-up, characterized by a displacement in the two-dimensional (2D) lattice and a C-shape bowing in the three-dimensional (3D) lattice. The relative deviations of isotopic concentrations induced by the bowing effect are quantitatively investigated for four specific isotopes: 235U, 239Pu, 244Cm and 148Nd with the SERPENT-2 Monte Carlo code. For qualitative estimations, azimuthal and longitudinal distributions are also illustrated in the 2D and 3D models.