Design and thermal-hydraulic analysis for CFETR divertor OVT in consideration of RH compatibility

The divertor is a key in-vessel component of the China Fusion Engineering Test Reactor (CFETR), which is mainly used to remove high heat load and exclude particles. In addition, the CFETR divertor also needs to meet requirements of Remote handling (RH) maintenance due to activation of materials by neutrons. CFETR proposed the concept of hybrid divertor-blanket to meet the requirements mentioned above and improve tritium breeding ratio (TBR). The new concept cancels the cassette and adopts a separate structure. Space below the divertor is occupied by the breeding blanket to improve TBR, and targets are directly fixed on the breeding blanket to improve RH maintenance efficiency. The outer vertical target (OVT) is a high heat load component of the divertor, which needs to remove the heat flux of 20 MW/m2 and neutron radiation heat at 1.5 GW fusion power and meet the requirements of RH maintenance. The structure design, RH compatible structure design, RH process and thermal-hydraulic analysis of OVT are completed in this paper. The relevant design effectively reduces the weight and complexity of RH maintenance and improves RH efficiency of OVT. RH process for OVT proves to have great engineering feasibility. Advanced low activation materials are adopted for OVT. Thermal-hydraulic analysis verifies that OVT can remove heat flux of 20 MW/m2 and neutron radiation heat at 1.5 GW fusion power, which confirms the rationality of the cooling system and effectively prompts the structural analysis of OVT.