A pressure suppression system is a well-established Engineered Safety Feature to deal with loss-of-coolant accidents (LOCA) or main steam line breaks, ensuring containment integrity during postulated accident conditions. To validate the effectiveness of these systems for a novel Small Modular Reactor, a scaled experimental test facility with a 1:8 ratio, maintaining the same height, was designed. This facility is used for the engineering verification of both the pressure suppression system and the passive containment cooling system. Currently, experiments on the pressure suppression system have been conducted, measuring the temperature and pressure in both dry and wet wells. The release of thermal energy in the experiment was scaled based on accident analysis results. The thermal energy release is divided into two stages: the blowdown stage, simulating high-pressure discharge during a break accident, and the constant-flow steam injection stage, simulating prolonged thermal energy release. The COCOSYS code was employed for both blind and open calculations. The blind calculation provided conservative estimates for containment pressure, while the open calculation involved a sensitivity analysis of node discretization based on experimental data. The results demonstrate that an optimized node discretization significantly improves the accuracy and reliability of the analysis.