This paper presents preliminary thermal-hydraulics calculation results for a small modular reactor (SMR) with a thermal capacity of 200 MW based on the ACPR50S reactor technology (Advanced customerfriendly practicable reliable 50 MWe compact SMR). The basic parameters and thermal-hydraulics safety were assessed, including the heat coolant flow through the core, fuel, and cladding temperatures to ensure the reactor’s capability to operate within safe limits. The SMR configuration was simulated using the RELAP5 program and performed the calculation in about 500 seconds in the steady state. The coolant temperature of the heat carrier along the height of the core at the inner and outer was found to be different (1.7%) f-rom the reference value. Regarding safety, the departure f-rom nucleate boiling ratio (DNBR) was also estimated along the average channel and the hottest channel of the core in the steady state. The results f-rom this study will be further used in transient computations and incident analysis for SMRs.