"Exploring the role of lithium in Al2O3 tritium permeation barrier development: A crucial challenge for fusion reactor progress"

• Published in: Journal of nuclear materials Vol. 602; p. 155354
• Main Authors: Carella, E., de la Cuerda-Velázquez, G., Angiolini, M., González-Arrabal, R., Bulla, A., Palermo, I., Di Fonzo, F., Sanchez, F., London, A.J., Hernández, T., Moroño, A., Stinchelli, A., Moody, M., Spagnuolo, G.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2024
• Subjects: Breeding Blankets; Coatings; Corrosion; Hydrogen retention; Lithium interaction; Tritium diffusion; Lithium interaction; Breeding Blankets; Hydrogen retention; Corrosion; Coatings; Tritium diffusion
• ISSN: 0022-3115
• DOI: 10.1016/j.jnucmat.2024.155354

•Addressing coatings challenges in fusion energy applications is crucial to minimize tritium permeation and shield structural materials from interactions with PbLi.•Tritium permeation into structural materials and subsequent recombination in the coolant significantly diminishes reactor efficiency and safety.•The transportation of dissolved and activated corrosion products by PbLi can lead to blockages in colder sections of the system, posing a significant safety concern.•The presence of lithium within the tritium permeation barrier could lead to the generation of helium and tritium through neutron transmutation. This process might promote the detachment of the coating from the structural material The development and application of robust tritium permeation barriers (TPBs) are crucial for a safe and economical fusion reactor operation because tritium permeation could cause serious safety problems, such as the brittleness of the structural material, fuel loss, and radioactive contamination. Coatings may effectively inhibit the permeation through the structural materials of tritium fuel generated inside the breeding blanket (BB) reducing the loss of lithium inventory contamination of the ancillary systems and the exposure of workers and the population. Al2O3 has been preliminary selected as the EU candidate for tritium permeation reduction of structural steels in the Water-cooled lithium–lead breeding blank (WCLL) concept, because of its very high permeation reduced factor (PRF). However, because of the chemical reactivity of lithium, several authors report the formation of Lithium aluminates after exposure to PbLi baths, based on different experimental techniques. In this contribution, we will show recent results about the quantification of the extent of the reaction and the thickness of the reacted layer and discuss the possible effects, that may happen under neutron irradiation based on the species produced (T and He) in the nuclear reactions (n, T) and (n, α) with 6Li and 7Li, with the Li atoms in the reacted layer To do that, the atomic density of produced T and He per second out of the transmutation reaction and the He/T ratio are calculated for diverse Li contents. Subsequently, we implant He into the coatings and characterize the desorption rate and the morphology. Finally, discussion and recommendations for further coating development will be presented.