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Preparation of Activation Experiments for ITER Material Characterization in JET

This presentation discusses the preparation and experiments for activating and characterizing ITER materials in the JET tokamak.

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Preparation of Activation Experiments for ITER Material Characterization in JET

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  1. 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

  2. Roadmap towards fusion Not in scale 2-4GW 500MW 38 MW ITER (under construction) JET (in operation) 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 • JETis considered as the test bed for ITER technologies HNPS 2016, NCSRD, Athens, 3-4 June 2016

  3. ITER material characterization • ITER materials • structuralmaterials 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

  4. ACT Project • 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

  5. 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

  6. ITER materials • 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

  7. Dosimetry Foils 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

  8. 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

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

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

  11. 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

  12. 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 campaignand 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

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

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