Tritium Extraction Technologies in Liquid Metal Breeding Blankets

The development of liquid metal breeding blankets for fusion reactors relies critically on the efficient removal of tritium produced within the circulating eutectic alloy, typically lead–lithium (PbLi). Tritium extraction must be achieved continuously and at sufficient rates to ensure a closed fuel cycle, maintain operational safety, and uphold self-sufficiency of the reactor. Central to this endeavour are membrane-based permeation techniques—chiefly the Permeator Against Vacuum (PAV)—and gas–liquid contactor arrangements or free-surface (FS) systems. These technologies operate by driving dissolved tritium across selective barriers into low-pressure circuits, where it is recovered for purification and reuse. Key technical challenges include optimising membrane materials (for example niobium), mitigating corrosion and hydrogen isotope recombination, and integrating the extraction modules seamlessly into the coolant and tritium processing loops of ITER and DEMO-class devices. Advances in analytical modelling capture the interplay of convective transport, diffusion in the bulk liquid, surface recombination kinetics and permeation through solids, providing design rules for module sizing and performance prediction. Experimental mock-ups at reactor-relevant temperatures and flow conditions furnish critical data on permeation fluxes and system dynamics, guiding the evolution towards compact, reliable tritium extraction units suitable for deployment in next-generation fusion power plants.

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Tritium Extraction Technologies in Liquid Metal Breeding Blankets publication trend

The graph below shows the total number of articles in tritium extraction technologies in liquid metal breeding blankets across all publications each year (not limited to Nature Index journals).

Technical terms

Breeding Blanket: A reactor subsystem containing neutron-multiplying and tritium-producing materials, here using liquid metal, to generate and recover fuel within a fusion device.

Permeator Against Vacuum (PAV): A tritium extraction module that drives dissolved hydrogen isotopes through a selective membrane into a vacuum-maintained permeate side for subsequent capture.

Gas–Liquid Contactor (GLC): An extraction arrangement where a gas phase (often sweep gas or vacuum) is brought into intimate contact with the liquid metal to strip dissolved tritium via surface mass transfer.

Free-Surface (FS) Configuration: A tritium removal scheme relying on direct permeation of isotope atoms across the liquid metal’s exposed surface into a low-pressure region without an intervening membrane.

PbLi Eutectic: A binary alloy of lead and lithium, optimised for melting point and neutron multiplication, widely adopted as the tritium-breeding medium in liquid metal blankets.

References

1. Design and Integration of the WCLL Tritium Extraction and Removal System into the European DEMO Tokamak Reactor. Energies (2023).
2. Theoretical evaluation of the tritium extraction from liquid metal flows through a free surface and through a permeable membrane. Nuclear Fusion (2023).
3. Tritium Extraction from Lithium–Lead Eutectic Alloy: Experimental Characterization of a Permeator against Vacuum Mock-Up at 450 °C. Energies (2023).