High heat flux testing of EU tungsten monoblock mock-ups for the ITER divertor

With the aim to assess the option to start the ITER operation with a full tungsten divertor, an R&D program was launched in order to evaluate the performances of tungsten (W) armoured plasma facing components (PFCs) under high heat flux. The F4E program consisted in the manufacturing and high heat flux (HHF) testing of W monoblock mock-ups and medium scale prototypes up to 20 MW/m(2). During the test campaign, 26 W mock-ups and two medium scale prototypes manufactured by Plansee SE (Austria) and by Ansaldo Nucleare (Italy) have been tested at the FE200 (AREVA, Le Creusot, France) and ITER Divertor Test Facility (IDTF) (Efremov Institute Saint Petersburg, Russian Federation) electron beam test facilities. The high heat flux (HHF) testing program foresaw the performance of 5000 cycles at 10 MW/m(2) and 300 + 700 cycles at 20 MW/m(2), 10 s power on and 10 s dwell time with ITER relevant hydraulic parameters. The test results fulfilled the ITER qualification requirements, although a few items did not sustain the extended test program (additional 700 cycles at 20 MW/m(2)), the analysis of the results gave indications on potential improvements, in particular concerning the W material itself with the objective to remove the self-castellation of the W monoblocks and concerning the thermo-mechanical fatigue performances of the CuCrZr heat sink. In addition, some critical heat flux experiments, whose results confirmed those previously obtained were also performed. (C) 2014 Elsevier B.V. All rights reserved.