Current plans and efforts of reactor operators and vendors to include extended-enrichment (EE) fuel and accident-tolerant fuel (ATF) in current reactor fleets motivate the study of these changes in reactor physics analysis. This work uses the U.S. Nuclear Regulatory Commission’s core simulator PARCS to do the core calculation and the SCALE Polaris lattice physics code to generate the homogenized, few-group constants. In this work, both pressurized water reactor and boiling water reactor (BWR) colorset models are used to verify the proposed approach. The accuracy presented in the colorset models verified the capability of the PARCS/Polaris procedures for the transition core analysis in light water reactors. For the whole-core calculation, the ATF and EE-ATF transition core models were incorporated, in addition to the nominal core model. The BWR model was chosen to represent the entire core calculation due to its challenging design. The core parameters studied are the core power distribution, power peaking factor, Doppler temperature coefficients, and control rod worth at cold zero power and hot full power. When the core parameters of the transition cores are compared with those of the nominal core in PARCS, the results suggest that there is no drastic change in the core parameters for the implementation of ATF and EE fuels.
