Preparation of activation experiments for ITER material characterization and data validation in the Deuterium–Tritium JET campaign T. Vasilopoulou & I.E. Stamatelatos, NCSRD, Greece L. W. Packer & S. Lilley, CCFE, UK P. Batistoni, ENEA, Italy

Roadmap towards fusion Not in scale 2-4 GW 38 MW 500 MW JET (in operation) ITER (under construction) DEMO (under design) Fusion power: a safe, clean, and limitless energy source for the future A fusion reactor builds in the main on three devices: JET, ITER and DEMO JET is considered as the test bed for ITER technologies HNPS 2016, NCSRD, Athens, 3-4 June 2016

ITER material characterization ITER materials structural materials used in the manufacturing of the main in-vessel components functional materials used in diagnostics and heating systems Why? ITER materials need to satisfy a range of requirements: their mechanical properties must be maintained in an environment of severe mechanical, electro-mechanical and thermal stresses high radiation field, including neutrons with energies up to 14 MeV an intense flux of charged particles, photons and other radiation low activity levels, since neutron activation of the structure can lead to medium-term radiation complicating the handling of components in maintenance or decommissioning operations long-term activation which requires special treatment, storage or disposal as waste at end of the plant life HNPS 2016, NCSRD, Athens, 3-4 June 2016

ACT Project Preparation of ITER materials irradiation experiment Activation experiments project (ACT): Nuclear analysis and characterization of real ITER materials Experiments and simulations performed at JET Scope of the present work Preparation of ITER materials irradiation experiment to be performed during the JET Deuterium–Tritium campaign Updated JET schedule HNPS 2016, NCSRD, Athens, 3-4 June 2016

Long Term Irradiation System (LTIS) Neutron spectra at LTIS Installed before the 2015 D-D campaign, filled with activation foils in order to characterize the local neutron field Will be used in the forthcoming T-T and D-T JET campaigns, carrying dosimetry foils and samples of ITER materials HNPS 2016, NCSRD, Athens, 3-4 June 2016

ITER materials 23 ITER materials studied No. Component Material Supplier Type 1 Vacuum Vessel SS316L(N)-IG Outokumpu Plate Industeel Kind Forging Thyssen 2 In-wall shield SS304 (borated) - Borated steel Alloy 660 3 First Wall 316L(N) CuCrZr 6 Divertor W Bar, plates OF-Cu Plates 7 XM-19 Plate forgings Al-bronze Forgings 9 Toroidal Field Coils SS316L(N) Radial plates Nb3Sn BEAS Mixture SS316L Cover plates NbTi 9a Hyundai TF coil case Daido steel 23 ITER materials studied Both structural and functional components Material composition data provided by manufacturers and ITER basic model literature [1] [1] V. Barabash (2013) ITER IDM:HTN8X3 HNPS 2016, NCSRD, Athens, 3-4 June 2016

Dosimetry Foils To monitor neutron fluence data from FENDL-3.0 To monitor neutron fluence Discs D=18 mm, thickness=1 mm Selection based on Response on neutron energy Half-lives Material properties (i.e. melting point) Threshold reactions Ti, Mn, Co, Ni, Fe, Y Neutron capture reactions Co, Sc, Ta, Fe HNPS 2016, NCSRD, Athens, 3-4 June 2016

Calculations European Activation System (EASY-II) EAF-2010 nuclear data library D-T plasma source neutron spectrum at LTIS Detailed MCNP model of JET (tokamak and hall) Total neutron fluence of 1.06×1016 cm-2 (4 months) Fluence rate of 1.02×109 cm-2·s-1 (continuous scheme) Output Specific activity (Bq/g) Dose rate at 1 m (Sv/h) Detector count rate (cps) Cooling times ranging from 1 d to 600 d Model of JET tokamak HNPS 2016, NCSRD, Athens, 3-4 June 2016

Results: Specific activity (1) Vacuum Vessel Toroidal Field Coils In-wall shield HNPS 2016, NCSRD, Athens, 3-4 June 2016

Results: Specific activity (2) First Wall TFC conductors Divertor materials HNPS 2016, NCSRD, Athens, 3-4 June 2016

Results: Dose rate Dose rate per gr at 1m 200 d post-irradiation dose rates per gr at 1m distance are bellow 1 Sv/h for all materials The dose rate calculated for material Nb3Sn is attributed to the different impurity content and in particular to the high level of Ta resulting in significant 182Ta production 200 d post-irradiation the dose rate at 5 cm distance from Nb3Sn material is ≈ 40 μSv/h HNPS 2016, NCSRD, Athens, 3-4 June 2016

Concluding remarks The preparation for D-T irradiation experiment has been completed ITER samples will be installed in LTIS in 2018 for the T-T campaign and in 2019 for the D-T campaign Manageable activities and dose rates are expected to be acquired after irradiation For accurate prediction of activity levels and dose rates, exact knowledge of impurity levels is of outmost importance Unique opportunity to study ITER materials under real fusion conditions HNPS 2016, NCSRD, Athens, 3-4 June 2016

Thank you for your attention! JET tokamak dora@ipta.demokritos.gr