The Fukushima incident provided the lesson that spent fuel storage pool (SFSP) require adequate analysis of thermal performance. This study aims to investigate the dynamic behaviors of SFSP under normal- and station blackout (SBO) conditions. The well-mixed approach is utilized and considers the heat and mass transfer processes in developing a dynamic model using Stella software. This dynamic model is validated against experimental data undertaken at the G.A. Siwabessy Reactor SFSP. The model's predicted results are in good agreement with the experimental data, with a mean relative deviation (MRD) of 0.0085%–0.042% and a mean squared error (MSE) of 0.0006–0.0047. The simulation results show that the cooling system requires additional time operation in the planned addition of spent nuclear fuel (SNF). The survival time under SBO without human intervention for current inventory, addition of 120 SNF, and 60-years reactor operation are 142 days, 104.4 days, and 45.8 days, respectively. © 2021 Elsevier Ltd