2018 | AFC ACCOMPLISHMENTS 73 factor in deployment.Analysis of these responses is complicated by the significant temperature and flux gradients that are developed over the length of the channel box.This project aims to demonstrate and refine coupled modeling approaches to understand channel box deformation to guide execution of future irradiation testing. Project Description: A multi physics thermal-mechanical analysis was performed to evaluate the performance of silicon carbide composite fuel channel box in a BWR.The analysis involved providing neutronic and thermal-hydraulic boundary conditions using the Serpent and CTF codes, respectively, to inform a finite element thermal-mechanical analysis usingABAQUS and BISON. Figure 1 presents the temperature and fast (E>0.1MeV) neutron flux profiles in the BWR channel box.The neutronic-thermohydraulic model contained 119 coolant sub-channels, 92 fuel rods, and space for two large water rods. Seven axial locations using 2D geometry were selected for the neutronic-thermohydraulic calculations, and the results at these locations were interpolated to form a 3D map of the temperature and neutron flux. Accomplishments: A channel box was created in the models by placing a heat slab structure with thermal properties of nuclear- grade SiC-SiC composites around the perimeter of the fuel pin lattice.The geometric dimensions for the model were representative of a GE14 BWR assembly.The outer cross-sectional width was 14.02 cm, the wall thickness was 3.05 mm, and the height of the channel box was 371 cm. Default material properties provided in CTF for UO2 fuel and zirconium-based cladding were implemented.The spacer grids are modeled based on BFBT 8x8 spacer grids with modified loss coefficients. The average axial power profiles for the model were obtained from the literature, and the radial heterogeneity in the power and neutron flux is directly Modeling of SiC-SiC channel box performance quantifies impact of swelling on dimensional stability during normal operation.