About this Abstract |
| Meeting |
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Symposium
|
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Presentation Title |
Evaluation of Hydrogen Isotope Transport in Advanced W Alloysfor Plasma Facing Materials |
| Author(s) |
Yasuhisa Oya, Yuzuka Hoshino, Shingo Okumura, Ayumu Hayakawa, Kenshiro Mura, Fei Sun, Suguru Masuzaki, Robert Kolasinski, Chase N. Taylor, Masashi Shimada |
| On-Site Speaker (Planned) |
Yasuhisa Oya |
| Abstract Scope |
Tungsten (W) is thought to be one of the best candidates for the fusion plasma facingmaterial from the viewpoint of tritium (T) retention. However, findings from the Japan-US collaboration program PHENIX and FRONTIER showed that the irradiationdamage enhances hydrogen isotope retention, where the stable trapping sites areintroduced by neutron irradiation, leading to the potential hazard for fusion safety.Recently, the W alloying with minor elements like rhenium (Re), molybdenum (Mo),tantalum (Ta) has been proposed to enhance the recrystallization temperature andmaterial strength. In addition, potassium (K) doping with lower concentration is anotheroption to diminish irradiation defects by forming K bubbles. In this study, the hydrogenisotope retention/permeation in W-Re, W-Mo, W-Ta and K-doped W was extensivelyinvestigated, with a focus on correlating retention behavior with the irradiation-induceddefect.The 6 mm diameter with 0.5 mm thickness samples for W-1-5%Ta, W-5.2%Mo and40ppm K-doped W were prepared with minor surface. Some of these samples weredamaged by energetic 6 MeV Fe2+ irradiation by TIARA facility in QST up to thedamage level of 1 dpa at room temperature. The size and density of irradiationdamages was evaluated by Positron Annihilation Spectroscopy (PAS). High flux Dplasma exposure with the ion fluence up to 7 x 1025 D m-2 or the 3 keV D2+ ionimplantation with the ion fluence of 1 x 1022 D m-2 was performed at ShizuokaUniversity. Thermal desorption spectroscopy (TDS) was applied to find out the Ddesorption behavior. The plasma driven permeation was also studied for severalsamples. The hydrogen isotope diffusion and trapping (HIDT) code was applied tosimulate the hydrogen dynamics.
The results showed that no large D retention enhancement was found for present W alloys, but the D trap density with higher trap energy was reduced. The D trapping by mono-vacancy with lower trap energy was the major D trapping state for K-doped W. For W-Mo and W-Ta, the addition of minor element would occupy the irradiation defects, leading to the refrain of D trapping with stable D trap energy. |
| Proceedings Inclusion? |
Undecided |