Search

C enters the atmosphere in amounts equivalent to 1.4 PBq/yr with total accumulation 140 PBq via cosmic radiation. As a result of nuclear explosions (1950-1969), its activity in the atmosphere exceeded 200 PBq. At present, C has been completely removed into bottom waters and sedimentary rocks in the ocean. The activity of the C entering the atmosphere from all operating nuclear reactors equals ~0.3 PBq/yr and the amount from all spent fuel reprocessing facilities equals ~0.06 PBq/yr. The admissible levels of C emissions must not exceed levels corresponding to peroral intake dose 10 μSv/yr. This is can be accomplished by means of a system of measures: reduction of the volume of technogenic gases and their CO content, combining high-efficiency purification with dispersion through high exhaust-stacks, and developing new technologies and reagents binding C in compact forms. [ABSTRACT FROM AUTHOR]

Methods for trapping the C in waste gases by means of a combined technology are examined. The wastes gases from pyrochemical production can be purified by removing C by passing the gases at rates to 5 m/h through a 0.5 m high layer of Ba(OH)·8HO granules in a 0.14 m in diameter apparatus after dilution with atmospheric air. The purification of the waste gases from hydrometallurgical production by removal of C (50 m/h) is best accomplished by passage through a 0.28 m in diameter packed tower with 2.7-4 m high packing irrigated by an alkali solution which is regenerated by means of calcium hydroxide. The waste gases from pyrochemical production can also be passed through a packed tower. In this case the C is fixed in insoluble calcium carbonate and is placed in a storage facility and subsequently buried. The proposed technologies make it possible to purify the waste gases formed during the reprocessing of spent uraniumplutonium nitride nuclear fuel in a reprocessing module used in an on-site nuclear fuel cycle by removing C to a level admissible for air in production enclosures. [ABSTRACT FROM AUTHOR]