The Numerical Nuclear Reactor is a collaborative US-ROK I-NERI project to develop a comprehensive high fidelity reactor core modeling capability for detailed analysis of current and advanced reactor design. High fidelity models of thermal-hydraulics and neutronics have been incorporated into the initial version of the integrated code. Computational fluid dynamics (CFD) methods, based on the STAR-CD commercial CFD code, are used for the thermal-hydraulic analysis, while neutronics calculations are being performed with the whole core discrete integral transport code, DeCART. A robust coupling strategy for integrated, high-fidelity thermal-hydraulic/neutronic calculations has been developed. Examples of the coupled code analysis capability are provided for single pin, multi-pin and mini-core configurations, as well as estimates of computational requirements for integrated whole core calculations.