When cosmic rays enter the atmosphere, they undergo various transformations, including the production of neutrons.The resulting neutrons ( but attempts to directly measure the production rate in situ were not very successful.Such deposits often contain trace amounts of carbon-14.These amounts can vary significantly between samples, ranging up to 1% of the ratio found in living organisms, a concentration comparable to an apparent age of 40,000.), or other unknown secondary sources of carbon-14 production.However, open-air nuclear testing between 1955–1980 contributed to this pool.The different isotopes of carbon do not differ appreciably in their chemical properties.
This is small compared to the doses from potassium-40 (0.39 m Sv/year) and radon (variable).
Liquid scintillation counting is the preferred method.
during his tenure as a professor at the University of Chicago.
It is typically released to the atmosphere in the form of carbon dioxide at BWRs, and methane at PWRs., radioactive carbon dioxide.
The gas mixes rapidly and becomes evenly distributed throughout the atmosphere (the mixing timescale in the order of weeks).