[en] A heavy water process based on isotopic exchange between hydrogen and methylamine and methylamine and water has been developed by SULZER and Atomic Energy of Canada. Deuterium source is the synthesis gas stream of an ammonia plant. Deuterium enrichment is achieved by bithermal amine-hydrogen exchange, however, preliminary enrichment is made to occur in the reformers of the ammonia plant by using the steam reforming process as the decomposition step of a monothermal enrichment stage. This feature, coupled with the high value of the separation factor achievable with hydrogen-amine exchange, allows a high deuterium yield without the use of hydrogen recycle in the extraction stage. Design work has been based on pilot tests of the key process steps using industrial contacting equuipment. (Auth.)