Design and analysis of a direct reactor auxiliary cooling system for a pool-type small modular lead-based reactor.

• A Direct Reactor Auxiliary Cooling System (DRACS) has been designed to remove the core decay heat efficiently after transient accidents for a 10 MW LBE-cooled SMR. • The DRACS features a dual heat sink design, with water serving as the cooling source soon after accidents. As the water evaporated, the cooling source finally transitioned to be air. • Using RELAP5, the capability of the DRACS has been verified under the PLOFA, which effectively removed core decay heat while ensuring that the liquid lead–bismuth was not condensed. • Sensitivity studies have been conducted to verify the robustness of the DRACS by varying initial conditions. In this paper, a Direct Reactor Auxiliary Cooling System (DRACS) has been designed to remove the core decay heat after accidents such as the core scram to ensure the safety of a 10 MW pool-type Small Modular Lead-based Reactors (SMR). The DRACS is characterized by dual heat sinks, i.e., water and air. The protect loss of flow accident (PLOFA) has been simulated by RELAP5 to illustrate the thermal–hydraulic feathers in both the primary circuit system and the DRACS. The natural circulation was established in the flow path of the primary circuit where the DRACS was in operation. The complete evaporation of water caused obvious variation of LBE temperature, however, affected LBE mass flow rate marginally. Moreover, the DRACS was efficient in removing core decay heat and preventing LBE solidification under different initial conditions. The conclusions from the current work would help with the designs of decay heat removal systems for SMR. [ABSTRACT FROM AUTHOR]