Abstract: In an aspect, an electrochemical hydrogen isotope recycling apparatus for recycling a feedstream comprising a single isotope of hydrogen, comprising: an electrochemical recycling unit, the unit comprising an anode; a cathode; an isotope-treated, cation exchange membrane operatively disposed between the anode and cathode, the isotope-treated, cation exchange membrane having heavy water containing the isotope of hydrogen therein, the unit configured to receive the feedstream containing the single isotope of hydrogen; wherein the single isotope is deuterium or tritium and when the single isotope is deuterium, the heavy water comprises D2O and when the single isotope is tritium, the heavy water is T2O.

Abstract: A method of manufacturing electrochemical cell stacks of different sizes or configurations is disclosed in which a first planar module having a first planar size and configuration is assembled from a first inventory of parts including planar modular parts having mating surfaces along connectable ends. The planar modular parts are connected in a co-planar configuration to form the first planar module having the first size and configuration. A second inventory of parts including planar modular parts in common with the first inventory is identified, and a second planar module having a different planar size or configuration than the first planar module is assembled from the second inventory. The first and second planar modules are assembled with other planar modules and component to form electrochemical stacks corresponding to the planar size and configuration of the respective first or second planar module.