23° 19' N 73° 00' E
Indian heavy-water production supports domestic natural uranium [versus enriched uranium] nuclear power plants. Difficulties in supplying reactor inventories have been mitigated by nuclear power plant construction delays. A total of eight operating heavy-water plants have a total production capacity of more than 650 te/yr, adequate both to support current domestic requirements and export sales [including 100 te to South Korea and 350 te to Romania]. Six of the plants use ammonia exchange processes and are associated with fertilizer production plants, and the other two use the hydrogen sulfide process.
The Heavy Water Plant at Baroda was the first plant set up in India for the production of heavy water by employing ammonia-hydrogen exchange process (monothermal). The plant is about 8 km from Baroda railway station along national highway no.8. Work on HWPB was commenced in June 1970 and the project was completed in July 1977. Operation of the Heavy Water Plant at Baroda has been suspended with effect from 31 December 1998 due to non-availability of high pressure synthesis gas from GSFC's Ammonia Plants due to technological obsolescence. As an alternative Heavy Water Production Technology and also for sustaining operation of the Baroda Heavy Water Plant, due to closure of old ammonia plant of M/s Gujrat State Fertilizer Corporation, a first phase of the project called BAEP (Baroda Ammonia Extension Project), is on hand.
Synthesis gas (a mixture of one part of nitrogen and three parts of hydrogen) containing deuterium, produced in one of the adjacent ammonia plant for their captive use, is routed through the plant at a flow rate of about 46 T/hr. at a pressure of about 640 kgs./cm2. The gas is first cooled in a heat exchanger by the outgoing cold gas from the plant to ammonia plant. The gas is then passed through a purification unit. In this unit the impurities contained in the gas such as water, carbon monoxide, carbon dioxide and oxygen are removed and the gas is saturated with ammonia.
The cooled and purified synthesis gas saturated with ammonia is then passed through the first isotopic exchange tower working at (-)20 degree Celsius where deuterium in the gas transferred to a counter current stream of liquid ammonia fed from the top of the tower in the presence of liquid potassium amide catalyst contained in liquid ammonia solution. The deuterium enriched ammonia from the bottom of the exchange tower is then fed to the second isotopic exchange tower where it gets further enriched by coming in contact with the synthesis gas obtained by cracking of enriched ammonia. A part of the enriched gas and liquid from the bottom of second isotopic exchange tower is then taken to the final enrichment section where the concentration of deuterium in the ammonia can be further increased as desired upto 99.8%.
Finally, the enriched ammonia so obtained is cracked and a portion of this enriched synthesis gas is burnt with dry air to produce heavy water. However, for reasons of better recovery efficiency the concentration of deuterium in ammonia in the final enrichment section is kept at around 60%. An upgrading plant is set up to upgrade the 60% heavy water to nuclear grade.
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