Heavy liquid metals (HLMs) are promising candidates as coolants of Generation IV fast reactors due to their thermo-physical properties. In the last decade, experimental works have been proposed as part of Research & Development efforts to develop such systems. In this context, researchers from the Brasimone Research Center conducted many experiments using the Natural Circulation Experiment Upgrade (NACIE-UP) facility to study the thermo-fluid dynamic behavior of HLM in rod bundle configurations with or without wire wrappers. This facility consists of a rectangular loop operated with lead-bismuth eutectic. Sensors across the loop monitor relevant parameters, i.e., temperatures, heat transfer, and flow conditions. In the present work, we carefully select published data from NACIE-UP to validate the System Analysis Module (SAM), a modern system analysis code developed at Argonne National Laboratory. We developed one SAM model using specifications of the facility geometry and materials existing in relevant papers and reports. On top of that, these references provide the boundary conditions for simulating natural circulation and forced convection experiments in either steady or transient conditions. The SAM model simulates five test cases with diverse operating conditions. Ultimately, the code proves to predict temperatures and mass flow rates that closely match the experiments. The discrepancies between numerical predictions and diverse transients are limited to a few degrees Celsius, showcasing that SAM is well suited for analyzing nuclear systems relying on HLM coolants.
