Preliminary Design Progress of the CFETR Water-Cooled Divertor

The Chinese Fusion Engineering and Testing Reactor (CFETR) has been performed and is in its engineering design stage. Presently, there are two options allowed for the divertors; the helium-cooled stage and water-cooled stage. The water-cooled one has been focused in this article. The configuration of CFETR divertor module was designed. The cassette design scheme and cassette box inner and outer locking systems were introduced, and the locking system was designed to compliant with the remote-handling (RH) requirements. Two divertor RH design options were provided: one is removed through lower port; the other is targets and baffles removed through upper port; supports and cassette were not removed. The other major research was the water cooling channels' design and its pressure drop calculation. In addition, the fluid, thermal, and mechanical analyses on the outer target were done. Within 10-MW/m2 heat flux, outer target design can ensure that the temperature for all the components works within their temperature limit, and all the components meet the stress design criteria except the copper alloy pipe. The maximum primary stress induced by pressure on the copper alloy pipe appears in the local position between the two monoblocks, which exceeds the design limit. Protection components are need to be added at the gap of the future design optimization to reduce the local stress. After the thermal-hydraulic analysis on water-cooled divertor cassette, the maximum temperature and the maximum stress of cassette meet the requirements. The results of electromagnetic force analysis shows that the deformation on first wall and transition support is less than 0.5 mm, and the maximum stress is also below its tensile strength values. This article summarized the latest achievements in the design and research of CFETR water-cooled diverter in China. All the results will be of great reference for the CFETR divertor optimal design.