Analysis and modeling of the behavior of the KALIMER fuel assemble duct

The objective of this study is the modeling and analysis of the deflection behavior of KALIMER assembly ducts. The models including KALIMER core restraint system configuration and material property of HT9 duct were installed to NUBOW-2D KMOD, and the deflection behavior of assembly ducts is analyzed using the design factor in geometrical and material respect. Sensitivity analysis shows; TLP displacement by thermal bow only was up to 8mm. When the gap distances between ducts more than 2mm, unrestraint bow shapes are appeared from 1st assembly duct to 5th fuel assembly duct. Although external regions of the core have relatively low temperature and neutron fluence, assembly ducts are deflected due to the thermal expansion of grid plate. And the outermost 11th assembly duct deflection decreased about 10% when the gap distance between duct and restraint ring changes from 1 mm to 2mm