Design and fabrication of a Permeator Against Vacuum prototype for small scale testing at Lead-Lithium facility

•The manufacturing design of a Permeator Against Vacuum prototype is presented.•The PAV will be implemented in a PbLi loop to demonstrate the technique.•Operational inputs (mass flow, temperature) are evaluated for a fixed geometry.•Two approaches are compared in terms of efficiency, assembly and endurance.•A PAV based on vanadium membranes and steel supporting structure is proposed. Tritium recovery is one of the major issues of a future DEMO reactor, in order to comply with the requirements of tritium self-sufficiency. Within the EUROfusion Programme the permeation against vacuum (PAV) technique has been considered as baseline for those blankets which use PbLi as breeder. A conceptual design of a rectangular multi-channel PAV for its implementation in an experimental PbLi loop, under construction at CIEMAT, has been produced. A comparison between vanadium/niobium/tantalum and α-Fe membranes has been performed in terms of costs, machining, mechanical resistance and efficiency resulting in a design based on vanadium membranes and a stainless steel structure. Structural calculations are also presented, paying special attention to the interface between the membranes and the main structure in order to avoid leakages. Other important aspects such as keeping an adequate vacuum level have also been considered.