Impact of the monoblock thickness in an ITER-like configuration of DEMO divertor

Abstract The thermal-mechanical analyses carried out on the DEMO Divertor tungsten monoblocks have shown that the fatigue lifetime of the CuCrZr tube and copper interlayer, under cyclic thermal loads, depends on the axial thickness of the W. One of the monoblocks thickness currently considered for plasma facing component of the DEMO divertor is 4 mm. This configuration is compared with ITER design, where the W thickness is 12 mm. Both configurations have been simulated in ANSYS Workbench environment. In this paper, not the single monoblock, but an entire plasma facing unit (PFU) is analyzed with its constraints to the cassette. The FEM model consists of a CuCrZr tube 60 mm long, corresponding to the distance between two successive support attachment to the cassette as well in the current ITER divertor design. Between the W monoblocks and the tube 1 mm of pure copper interlayer is present. Appropriate symmetry conditions allow to simulate the entire PFU. The pipe and interlayer materials have elasto-plastic behavior, while the monoblock Tungsten is considered to have linear elastic properties. In this study the plastic fatigue lifetime of the CuCrZr tube and the copper interlayer has been estimated by applying a cyclic heat flux (20 MW/m 2 ) to the surface of the tungsten armor.