High heat flux testing of mock-ups for a full tungsten ITER divertor

Abstract

In order to evaluate the option to start the ITER operation with a full tungsten (W) divertor, the EU-DA launched an extensive R&D program. It consisted in its initial phase in the high heat flux (HHF) testing of W mock-ups and medium scale prototypes up to 20 MW/m 2 in the AREVA FE 200 facility (F). Critical heat flux (CHF) experiments were carried out on the items which survived the above thermal fatigue testing. After 1000 cycles at 10 MW/m 2, the full W Plasma Facing Components (PFCs) mock-ups successfully sustained either 1000 cycles at 15 MW/m 2 or 500 cycles at 20 MW/m 2. However, some significant surface melting, as well as the complete melting of a few monoblocks, occurred during the HHF thermal fatigue testing program representative of the present ITER requirements for the strike point region, namely 1000 cycles at 10 MW/m 2 followed by 1000 cycles at 20 MW/m 2. The results of the CHF experiments were also rather encouraging, since the tested items sustained heat fluxes in the range of 30 MW/m 2 in steady-state conditions.