The characteristics of the radiation field around a consolidated interim spent nuclear fuel storage facility were investigated comprehensively through Monte Carlo simulations. Neutron and gamma-ray flux/dose contributions from multiple transport pathways, including direct, streaming, skyshine, groundshine, and multishine, were isolated using a modified version of the method that was originally developed by Oh et al. [J. Korean Phys. Soc., Vol. 69, 1057 (2016)] for the evaluation of neutron skyshine from a high-energy electron accelerator. The application of the methodology was demonstrated in this paper, and the flux/dose contributions of individual pathways were examined and compared. The results provided additional insight into how the radiation propagated from the source to off-site locations. The modified method for separating five transport pathways can provide valuable information for shielding optimization during the design phase and is generally applicable to Monte Carlo shielding analyses of other nuclear facilities.