In March 2015, the Kingdom of Saudi Arabia signed an agreement with South Korea to build the system-integrated modular advanced reactor (SMART) originally developed by the Korean Atomic Energy Research Institute. The SMART is a structurally contained safe dual-purpose power plant reactor that produces both electricity and desalination. This study aims to design a double-containment structure with a pool-type concept to enhance the SMART safety and develop a robust design for future modular reactors. For that purpose, a theoretical model is developed herein, which leads to the modeling of a double-containment structural design of a water pool. The model calculates various parameters (ie, temperature, pressure, phasic velocities, and condensable gases) and is used to develop a simulation program for use in a computational assessment. Moreover, two best-estimate thermal hydraulic engineering programs, namely THEATRe and RELAP5, are used to simulate the original SMART with the double-containment water pool structure. The differences in the modeling strategies of the two simulation techniques are discussed to accurately measure various technical parameters. Accordingly, a nodalization diagram of the reactor and the pool-type concept are developed and simulated. The results obtained from the computational models yield the error of >2%, depicting accuracy. A small-break loss of coolant accident is also simulated to mitigate the transient conditions. The result verifies the adoptability of this reactor concept in any other small modular reactor.