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Tritium permeation into materials and anti-permeation coatings


   Tritium Innovation Unit

  Dr Walter Shmayda  Friday, March 24, 2023  Funded PhD Project (Students Worldwide)

About the Project

PhD awarding body: University of Rochester, NY, USA

PhD host: University of Rochester, USA

PhD sponsors: University of Rochester, USA & UKAEA, UK

PhD start date: Must be before 31st March, 2023

This project will involve experiments investigating tritium permeation into materials and anti-permeation coatings, including the application of anti-permeation coatings to materials.

Various fusion relevant materials will be investigated, including tungsten, molybdenum, EUROfer97, XM-19 nitric steel for corrosion resistance, ODS (14WYT), zirconium, SS304, SS316, inconel, hastelloy and a high purity iron-chrome alloy as a model stainless steel. The student will be based at UR where there is a working tritium laboratory.

The experimental work of the wider project will utilise facilities at both sites, but primarily at UR. At Culham UKAEA’s Hydrogen-3 Advanced Technology (H3AT) infrastructure will be used to expose materials samples to hydrogen isotopes using DELPHI (Device for Exposure to Low-energy Plasma of Hydrogen Isotopes). Analysis by TDS, NanoSIMS, TEM, SEM and XRD will be carried out at the UKAEA or external facilities to which the UKAEA have access.

At UR experimental work will be carried out using two facilities in the Laboratory for Laser Energetics (LLE) tritium lab. The Atomic Layer Deposition (ALD) system [1] will be used to apply anti-permeation coatings to materials. Coated and uncoated materials will be exposed to tritium in the tritium soaking facility [2]. Analysis of permeation into materials and through anti-permeation coatings will be conducted by etching samples an tritium content of etched layers will be assessed by Liquid Scintillation Counting (LSC).

The same materials and anti-permeation coatings will be tested at both UR and Culham to generate complementary results.

The project goal is to determine the expected fuel retention in fusion reactors as a function of tritium exposure to the different materials in different locations of the tritium facility or reactor, and as a function of anti-permeation coating in locations where tritium permeation is a significant issue, such as breeder blankets and heat exchangers. Excessive tritium permeation through anti-permeation barrier or into uncoated materials is likely to significantly impact the commercial viability of fusion as an energy source, and in the extreme could even make energy generation unfeasible. Of particular interest are the evolution of the retention topography along with the recently predicted plateau in damage density [3] which was recently confirmed experimentally in tungsten by the UKAEA led TRiCEM project [4,5].

The primary focus of the work in this PhD involves the ALD system at UR. Applying coatings to materials and checking the integrity of coatings. There will be involvement in the other work mentioned above with tritium soaking testing and tests using ion exposure. The ion exposure work will primarily be undertaken by UKAEA staff, but it is expected that the PhD will include some time in the UK, with involvement in the experimental work using the DELPHI facility. Initially the project work will involve re-commissioning the ALD system, followed by application of alumina coatings to SS316 to give a baseline for comparisons of other coatings (such as erbium) on the other materials of interest.


References

C. Fagan and M. Sharpe and W. T. Shmayda and W. U. Schröder, Fusion Sci. Technol. 76 (4), 424-429 (2020)
C. Fagan and M. Sharpe and W. T. Shmayda, Fusion Sci. Technol. 75 (8), 1053-1057 (2019)
P.M. Derlet and S.L. Dudarev, Physical Review Materials 4, 023605 (2020)
A. Hollingsworth et. al. Nucl. Fusion 60, 016024 (2019)
A. Hollingsworth et. al. Journal of Nuclear Materials 558, 153373 (2022)

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