###### Abstract  
Tritium permeation into the Primary Heat Transfer System (PHTS) of DEMO and ITER reactors is one of the challenging issues to be solved in order to demonstrate the feasibility of nuclear fusion power plants construction. Several technologies were investigated as antipermeation and corrosion barriers to reduce the tritium permeation flux from the breeder into the PHTS. Within this frame, alumina coating manufactured by Pulsed Laser Deposition (PLD) and Atomic Layer Deposition (ALD) are two of the main candidates for the Water Cooled Lithium Lead (WCLL) Breeder Blanket (BB). In order to validate the performance of the coatings on relevant WCLL BB geometries, a mock-up was designed and will be characterized in an experimental facility operating with flowing lithium-lead, called TRIEX-II. The present work aims to illustrate the preliminary engineering design of a WCLL BB mock-up in order to deeply investigate permeation of hydrogen isotopes through PHTS water pipes. The permeation tests are planned in the temperature range between 330 and 500 \({}^{\circ}\)C, with hydrogen and deuterium partial pressure in the range of 1-1000 Pa. The hydrogen isotopes transport analysis carried out for the design and integration of the mock-up in TRIEX-II facility is also shown.  
WCLL; ITER; DEMO; antipermeation barrier; corrosion barrier; lithium-lead Article Design of the Test Section for the Experimental Validation of Antipermeation and Corrosion Barriers for WCLL BB  
[PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON] Design of the Test Section for the Experimental Validation of Antipermeation and Corrosion Barriers for WCLL BB  
at a laboratory scale, and a preliminary scaling-up of the technologies was performed. The currently investigated fabrication technologies are PLD (Pulsed Laser Deposition), ECX (electro-chemical deposition) and ALD (Atomic Layer Deposition) [4]. The coating technologies were characterized from the point of view of the chemical compatibility in stagnant and flowing LiPb at 500 \({}^{\circ}\)C and of the capability to reduce the permeation flux and the electrical conductivity. The latter is necessary in order to reduce the pressure drops generated by the Magneto-Hydro-Dynamic (MHD) effect across the BB. These analyses were necessary to assess their applicability to DEMO and ITER reactors. The three selected Al\({}_{2}\)O\({}_{3}\)-barriers developed at a laboratory scale have shown good performances in the experimental characterization (permeation tests with and without gamma rays and electron irradiation, corrosion tests and thermal cycle characterization), but further upgrades are needed to coat real geometries and components. In order to demonstrate the applicability to WCLL BB, where it is requested to coat about 40,000 m\({}^{2}\) of water pipes and BB internals and 3700 m of LiPb pipes with 10\({}^{\prime\prime}\) diameter [1,4,5], a mock-up of WCLL water pipes will be manufactured and characterised in flowing LiPb with the support of the experimental facility TRItium EXtraction-II (TRIEX-II) installed at ENEA Brasimone Research Center. The coating processes investigated will be PLD and ALD techniques. The mock-up is designed with the feature to substitute coated tubes, allowing to test different geometries and/or coating manufacturing techniques at relevant WCLL operative conditions.  
The cost related to the PLD and ALD coatings manufacturing has been estimated taking into account 70% uptime and 80% productivity. The total cost of the layer deposition on the entire surface of a BB has been estimated to be about 300 kC. To this, it has to be added the capital investment (estimated to be about 1 M\(\cels\) for PLD and 0.8 M\(\cels\) for ALD) and the cost of manpower, considering about 3 years of work. In conclusion, the total cost due to the Al\({}_{2}\)O\({}_{3}\) coating proved for the full reactor to be about 2.0 M\(\cels\) for PLD and 1.8 M\(\cels\) for ALD coating manufacturing.