Background: Nitrate natural circulation loop (NNCL) is one of experimental platform in thorium-based molten salt reactor (TMSR)

which was designed to study the heat transfer behavior and corrosion behavior of direct reactor auxiliary cooling system (DRACS). Purpose: This study aims to implement a distributed control system (DCS) with functionalities of system control

online state monitor and experimental data acquisition in NNCL. Methods: An experimental physics and industrial control system (EPICS) based distributed control system was designed for this project. An optimized support module structure was designed for I/O operation with low-level PLCs to improve the performance of input/output controller (IOC) runtime database

and a PostgreSQL database was employed for data archive by RDB ChannelArchiver. A control system studio (CSS) interface and MATLAB was implemented in operator interface (OPI) computers

for visual operation and experimental data calculation. Results: Testing for online operation and history data acquisition in OPI interface proved that the control system satisfied all requirements of NNCL control and state monitor with long-term effective. Conclusion: The system could provide efficient and reliable routine for online operation and would well support advanced study of DRACS on this NNCL platform. Abstract