The method is an isotopic exchange process between H2S and H2O ("light" water), that produces heavy water over several steps. It is a highly energy intensive process. Normal water contains 155 parts per million of deuterium, relative to hydrogen.
Until its closure in 1997, the Bruce Heavy Water Plant in Ontario (located close to the Bruce Nuclear Generating Station) was the world's largest heavy water production plant, with a capacity of 700 tonnes per year. It used the Girdler sulfide process to produce heavy water, and required 340,000 tonnes of feed water to produce one tonne of heavy water.
Presently, India has seven heavy water production plants. The first of these to use the Girdler process is located at Rawatbhata near Kota, Rajasthan. .
Each of a number of steps consists of two sieve tray columns. One column is maintained at 30°C and is called the cold tower and the other at 130°C and is called the hot tower. Deuterium extraction is done based on the difference in separation between 30°C and 130°C.
Hydrogen sulfide gas is circulated in a closed loop between the cold tower and the hot tower. Demineralised and deaerated water is fed to the cold tower where deuterium migration preferentially takes place from the hydrogen sulfide gas to the liquid water. This "enriched" water from the cold tower is fed to the hot tower where deuterium transfer takes place from the liquid water to the hydrogen sulfide gas. An appropriate "cascade" setup accomplishes enrichment.
Normally in this process, water is enriched to 15% to 20% deuterium. Further enrichment to "reactor-grade" heavy water (>99% deuterium) is done in a vacuum distillation unit.
WIPO ASSIGNS PATENT FOR "DISTRIBUTED PRE-ENRICHMENT METHOD AND SYSTEM FOR PRODUCTION OF HEAVY WATER" (CANADIAN INVENTORS)
Feb 07, 2011; GENEVA, Feb. 7 -- Publication No. WO/2011/011876 was published on Feb. 03. Title of the invention: "DISTRIBUTED PRE-ENRICHMENT...
WIPO ASSIGNS PATENT FOR "CHLORATE AND CHLORINE DIOXIDE SYSTEMS ADAPTED FOR THE PRODUCTION OF DEUTERIUM ENRICHED WATER" (CANADIAN INVENTORS)
Feb 03, 2011; GENEVA, Feb. 3 -- Publication No. WO/2011/011877 was published on Feb. 03. Title of the invention: "CHLORATE AND CHLORINE DIOXIDE...