Design of a Multi-Tube Pd-Membrane Module for Tritium Recovery from He in DEMO

Abstract

Abstract:Dense self-supported Pd-alloy membranes are used to selectively separate hydrogen and hydrogen isotopes. In particular, deuterium (D) and tritium (T) are currently identified as the main elements for the sustainability of the nuclear fusion reaction aimed at carbon free power generation. In the fusion nuclear reactors, a breeding blanket produces the tritium that is extracted and purified before being sent to the plasma chamber in order to sustain the fusion reaction. In this work, the application of Pd-alloy membranes has been tested for recovering tritium from a solid breeding blanket through a helium purge stream. Several simulations have been performed in order to optimize the design of a Pd-Ag multi-tube module in terms of geometry, operating parameters, and membrane module configuration (series vs. parallel). The results demonstrate that a pre-concentration stage before the Pd-membrane unit is mandatory because of the very low tritium concentration in the He which leaves the breeding blanket of the fusion reactor. The most suitable operating conditions could be reached by: (i) increasing the hydrogen partial pressure in the lumen side and (ii) decreasing the shell pressure. The preliminary design of a membrane unit has been carried out for the case of the DEMO fusion reactor: the optimized membrane module consists of an array of 182 Pd-Ag tubes of 500 mm length, 10 mm diameter, and 0.100 mm wall thickness (total active area of 2.85 m 2 ).

Prospecting Stress Formed by Hydrogen or Isotope Diffused in Palladium Alloy Cathode

“…As explained before, high fictitious hydrogen pressure is not entirely in advantage, and it can lead to the coexistence of three solid phases in the thickness of alloyed palladium if the conditions are not respected. The presence of three phases modifies the mechanical behavior and the stress corrosion cracking for cathode of palladium alloy [21,22]. The hydrogen atoms in the β-phase push away the palladium atoms further to take up their location in the face-centered cubic lattice.…”