Improvements in enrichment systems for isotopes of hydrogen and/or oxygen

A new combination is disclosed of (I) a process for producing a substance enriched in a desired isotope of hydrogen and/or oxygen from a flow of liquid substance, e.g. water which becomes depleted in its content of said isotope, and (II) replenishing the liquid substance with said isotope by (a) direct contact with a flow of steam from a source external to the process, preferably geothermal steam, and (b) supplying feed flow of the process (I) from the so replenished liquid substance. Modes of improving the various forms of the process which employ dual temperature isotope exchange and their sub-combinations are also disclosed which enable higher temperatures and/or greater tower temperature differentials to be employed at reduced pressure, thus decreasing construction, energy, and other operating costs of the process, by the use in the process of certain hydroxylated and/or…