Thermal dynamic analyses of the primary heat transfer system for the WCCB blanket of CFETR

•The WCCB PHTS optimization was carried out to obtain uniform flow distribution.•Thermal dynamic behavior of the WCCB PHTS was analyzed under plasma pulse operation and MARFE transient.•CS1 and CS2 have different thermal dynamic behavior due to different thermal inertia.•The reliability of the WCCB PHTS is preliminarily verified. The Water Cooled Ceramic Breeder (WCCB) blanket is one of the blanket candidates of Chinese Fusion Engineering Testing Reactor (CFETR). The Primary Heat Transfer System (PHTS) of the WCCB blanket has been updated to fulfill the requirement of operating under 200 MW∼1.5 GW of fusion power based on the lasted CFETR design. The PHTS has two independent Cooling Systems (CSs). CS1 provides coolant for the First Wall (FW) and CS2 for Breeding Zones (BZs). In this paper, the PHTS design is optimized to obtain more uniform flow distribution among blanket sectors. Based on the optimized PHTS, plasma pulse operation and the Multifaceted Asymmetric Radiation From the Edge (MARFE) transient are simulated using RELAP5 to study the thermal dynamic behavior of the WCCB PHTS. The results show that CS1 and CS2 have different thermal dynamic behavior during plasma pulses due to different thermal inertia. Different schemes are considered for CS1 and CS2 to couple with the Power Conversion System (PCS). As for the MARFE, thermal hydraulic parameters of CS1 can return to steady state soon after the transient. The WCCB PHTS design is preliminarily evaluated as reliable according to thermal dynamic analyses.