14C Entry into the Atmosphere

14C 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, 14C has been completely removed into bottom waters and sedimentary rocks in the ocean. The activity of the 14C 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 14C 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 12CO2 content, combining high-efficiency purification with dispersion through high exhaust-stacks, and developing new technologies and reagents binding 14C in compact forms.