## 6 Conclusions and Future Work  
Within this paper, the design of a mock-up for the characterization of antipermeation and corrosion barriers for the WCLL Blanket of ITER and DEMO reactors was presented. It will be used for the characterization of the coating deposition process on EUROFER pipes from the point of view of hydrogen isotopes permeation and it will be installed in TRIEX-II facility at ENEA Brasimone research center, Italy. The mock-up will be internally coated by ALD technique to reduce as much as possible parasitic solubilization of hydrogen or deuterium either solubilized in the liquid lithium-lead or present in gas phase, according to the different steps foreseen in the experimental campaign. The design was carried out in order to guarantee an accurate determination of the PRF associated to the different coatings.  
From the results reported in Section 5, it can be observed that the permeation flux in liquid phase is higher than the one in gas phase only for hydrogen partial pressures lower than 70 Pa; for instance, for p = 10 Pa, the ratio between the two fluxes is 1.5. This is due to the fact that the permeation regime becomes closer to a SLR, in which, at the limit, the permeation flux in liquid phase is twice the one in gas phase. In general, for pressures higher than 70 Pa, the permeation flux in gas phase is the highest (at 1000 Pa is 2.8 times higher than the flux in liquid phase).  
Future work will regard two main aspects. Firstly, the finalization of the design and the construction of the test section, along with the installation in TRIEX-II. Secondly, concerning numerical simulations, a 3D numerical transport code which takes into account also the LiPb velocity field in the mock-up will be developed and benchmarked against the obtained experimental results. Additional sensitivity analyses on the surface parameters of EUROFER can be carried out in order to take into account possible oxidation of the steel.  
Figure 5: Molar rate as a function of the hydrogen partial pressure in liquid phase.  
**Author Contributions:** Conceptualization, M.U., C.A., L.C., F.P. and A.V.; methodology, M.U., C.A. and L.C.; software, L.C.; validation, C.A. and L.C.; formal analysis, M.U., C.A., L.C., F.P. and A.V.; resources, M.U.; data curation, M.U., C.A., L.C., F.P. and A.V.; writing--original draft preparation, M.U., C.A., L.C., F.P. and A.V.; writing--review and editing, M.U., C.A., L.C., F.P., D.F. and A.V.; visualization, M.U., C.A., L.C., F.P. and A.V.; supervision, M.U.; project administration, M.U.; funding acquisition, M.U. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.