Table 13.2 lists all plants in the non-Communist world that have been built or are planned for production of deuterium, in the form of heavy water, at a rate of 1 t/year or more.

The following general comments may be made about these plants and processes:

0. All plants, except 16 and 18, have a different process for primary enrichment than for final concentration.

1. Those plants that for primary concentration use water distillation (WD) or the dual­temperature, water-hydrogen sulfide (GS) process are self-contained plants whose sole product is heavy water.

2. All other plants that for primary concentration use water electrolysis (WE), steam-hydrogen exchange (SH), synthesis gas distillation (SD), hydrogen distillation (HD), or ammonia — hydrogen exchange (AH) are parasitic to a synthetic ammonia plant. Heavy water is a by-product of these plants, and its production rate is limited by the amount of deuterium in the ammonia plant feed.

3. Water distillation is used for final concentration in all plants still operating, except 16 and 18

4. The relative amount of heavy water produced by each primary concentration process up to 1975 was reported [M7] to have been

90%, GS process

6%, water electrolysis and steam-hydrogen exchange 2%, hydrogen and synthesis gas distillation

+ Organizations: AECL, Atomic Energy of Canada, Ltd.; DAE, Dept, of Atomic Energy, India; GELPRA, Groupement Eau Lourde Precede Ammoniac; ONIA, Organisation Nationale Indus — trielle de l’Azote; SCC, Societe Chimique de Charbonnage; U. S. AEC, U. S. Atomic Energy Commission; U. S. DOE, U. S. Department of Energy.

* Processes: AD, ammonia distillation; AH1, monothermal ammonia-hydrogen exchange; AH2, dual-temperature ammonia-hydrogen exchange; GS, Girdler-sulfide, dual-temperature, water- hydrogen sulfide exchange; HD, hydrogen distillation; SD, ammonia synthesis gas distillation; SH, steam-hydrogen exchange; WD, water distillation; WE, water electrolysis.

§ Scheduled start-up year.

1%, ammonia-hydrogen exchange

0. 3%, water distillation

The rest of this chapter is organized according to process rather than individual plants. The simplest and most familiar process, distillation, is taken up first.

Section 3 describes the separation factors obtainable in distillation of the principal substances used in isotope separation. Section 4 describes deuterium concentration plants using distillation of hydrogen or ammonia synthesis gas. Section 5 describes use of water distillation for primary deuterium concentration, for final deuterium concentration, and for separation of oxygen isotopes.

Section 6 describes the enrichment of deuterium in electrolysis of water. Section 7 describes how steam-hydrogen exchange has been used to increase the recovery of deuterium in electrolytic hydrogen plants.

Section 8 summarizes separation factors obtainable in isotope exchange reactions and their temperature dependence. The latter is the key property in dual-temperature exchange processes. Section 9 develops equations to be used for calculating the number of theoretical stages needed in exchange separation towers.

Section 10 describes monothermal exchange processes, with principal emphasis on ammonia-hydrogen exchange.

Section 11 describes the principle of dual-temperature exchange processes with particular reference to the water-hydrogen sulfide exchange reaction and gives more detailed engineering information about plants using this, the GS process, the process of greatest commercial significance.

Dual-temperature exchange processes using ammonia and hydrogen, methylamine and hydrogen, and water and hydrogen are described in Secs. 12, 13, and 14, respectively, and are compared with the GS process in Sec. 14.

Section 15 gives a brief description of exchange processes for separating lithium isotopes, and Sec. 16 gives a limited account of exchange processes for separating isotopes of carbon, nitrogen, oxygen, and sulfur.