About this Abstract |
| Meeting |
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Symposium
|
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Presentation Title |
Effect of Dispersoids and Cavities on H Permeation in Materials |
| Author(s) |
Steven J. Zinkle, David Sprouster, Lance Snead, Weicheng Zhong, Mediha Merve Karatas |
| On-Site Speaker (Planned) |
Steven J. Zinkle |
| Abstract Scope |
Permeation of H isotopes in materials is an important consideration for fission and fusion reactors. Hydrogen-containing materials are useful neutron moderators due to their similar mass to neutrons. However, most hydrides become thermally unstable above temperatures of 400-600oC, potentially limiting their use in Gen IV fission or proposed fusion reactors. One high-performance radiation shielding concept uses a composite consisting of metal– or ceramic-matrix and HfH2 dispersoids. The H in the dispersoid provides efficient neutron moderation, and the Hf can absorb the neutrons as they approach thermal energies. We have measured the deuterium permeability in Fe-HfH2 composites containing 40-70 vol.% HfH2 at 350-500oC and observed a 10-100X reduction in the H isotope permeability in these composite materials compared to pure Fe. This suppressed permeability is attributed to efficient trapping of diffusing H isotopes at the incoherent interfaces between the Fe matrix and dispersoids. This H isotopes trapping at the dispersoid-matrix interface should suppress thermal dissociation of HfH2 during long term operation at elevated temperatures due to retention of dissociated H at the outer periphery of the HfH2 particles. A model for H isotope permeation in composite materials indicates the H trapping energy is ~0.5-1 eV. Tritium permeation and sequestration (trapping) in first wall and blanket components is also a major topic for the feasibility of safe and economical fusion energy. Extension of this model to tritium trapping at cavities in irradiated structures predicts a substantial increase in the sequestered amount of tritium, which may have undesirable economic and safety implications. |
| Proceedings Inclusion? |
Undecided |