The report documents the analysis of the NAC International, Inc. (NAC) Modular, Advanced Generation, Nuclear All-purpose STORage (MAGNASTOR) module at Duke’s Catawba Nuclear Station ISFSL.  The MAGNASTOR modeled is a dual purpose canister-based system with a basket designed to hold 37 pressurized water reactor (PWR) fuel assemblies. It consists of a transportable storage canister (TSC) with a welded closure, a ventilated concrete storage cask, and a transfer cask.   The report describes the models developed and results of thermal analyses using best estimate data provided by the utility, Duke Energy, fuel assembly design information provided by the fuel vendors, Westinghouse Electric Company and AREVA, and decay heat estimates for each rod from Oak Ridge National Laboratory (ORNL) based on actual power history data.  Detailed models of the MAGNASTOR storage module were developed using two codes, COBRA-SFS and STAR-CCM+.  Simulations were run with COBRA-SFS to estimate fuel cladding temperatures at future dates, including 10, 50, 100, 200, and 300 years from the initial loading.  Peak assembly cladding temperatures were calculated with the COBRA-SFS and STAR-CCM+ models for the initial loading, using best estimate decay heats, and model results compared.