Electrochemical Extraction of Hydrogen from Molten LiF-LiCI-LiBr and Its Application to Liquid-Lithium Fusion Reactor Blanket Processing

The electrochemical evolution of hydrogen from a molten solution of LiF-LiCl-LiBr containing small quantities of LiH and saturated with metallic lithium has been demonstrated. The evolved hydrogen is recovered from the melt by sweeping the hydrogen electrode with a circulating stream of argon and subsequently trapping the hydrogen from the argon with a hot titanium getter bed. It is found that by continually gettering the argon, 100 ± 2% of the hydride present in the molten salt, at a concentration of 1 wppm, is recoverable. Results of metallographic examinations of stainless-steel components in contact with the salt solution during the experiments indicate some evidence of surface attack (10 to 15 µm) and intergranular penetration (30 to 50 µm), but extrapolated corrosion rates are generally small (∼0.2 mm/yr). These results incorporated into a reevaluation of the molten-salt extraction process, as it applied to tritium recovery from a liquid-lithium fusion reactor blanket, indicate a more favorable processing capability than was previously expected.