Abstract: The small integral pressurized water reactor (IPWR) has a more compact configuration than conventional loop-type pressurized water reactors because its primary components are integrated within a single reactor pressure vessel. This compact arrangement reduces piping length and the number of penetrations, thereby improving inherent safety, but it also changes the thermal-hydraulic behavior during accident transients. As a result, the post-accident response and safety system requirements of IPWRs differ from those of traditional large scale pressurized water reactors with separate loops and larger coolant inventories. Dedicated safety system design studies are therefore needed to support effective accident management. Among passive safety features, the suppression pool is a mature and reliable pressure suppression approach that has been applied in boiling water reactors and some advanced light water reactor designs. By promoting direct contact condensation of high-temperature steam discharged into the pool, it can rapidly absorb thermal energy, reduce containment pressure, and help maintain containment integrity under overpressure loads. In this study, a suppression pool system was introduced into an IPWR configuration to enhance pressure suppression capability, especially during the early stage of a postulated accident. The MELCOR code, a fully integrated severe-accident analysis tool developed by Sandia National Laboratories, was used to simulate a loss-of-coolant accident (LOCA) concurrent with a station blackout (SBO), representing a challenging multi-failure accident scenario. The pressure suppression performance was evaluated by analyzing the transient thermal-hydraulic response of the containment, including pressure and temperature. The effects of key parameters, including pool volume and initial water level, were also investigated. The results show that, compared with the case without suppression, the suppression pool can reduce the early peak containment pressure by up to 45.3%, effectively preventing premature overpressurization failure that could challenge containment integrity within the first few hundred seconds. Mechanism analysis indicates that non-condensable gases, mainly released from the break or displaced from the containment atmosphere, impair steam condensation on bubble surfaces and the pool free surface, causing a noticeable pressure increase over time. The results also show that pool volume and initial water level have an optimal range. An overly small pool rapidly becomes thermally saturated and loses heat sink capacity, whereas an excessively large pool increases structural weight and cost without proportional benefit. Within the optimal range, peak pressure suppression and long-term pressure control are well balanced. Overall, the suppression pool provides a promising passive safety strategy for IPWR pressure suppression and can be further optimized for specific plant designs.