[en] The rationale for ''cheap'' heavy water is discussed with emphasis on the economic, safety, and arms control implications of the widespread adoption of pressure-tube, heavy water moderated and cooled CANDU reactors, and variations thereof. Three classes of vibrational-photochemical laser processes are considered in detail, i.e., hydrogen halide-unsaturated hydrocarbon addition reactions, isotopically selective photoadsorption and photodesorption, and selective two-step molecular dissociation. General remarks are made concerning the economic viability of these techniques vis a vis hydrogen sulfide/water chemical exchange