Radioactive isotopes with groundwater

One of the more important factors affecting the isolation of radioactive waste is the rate of release of the radioactivity from the solid waste form to the environment. The most probable mechanism for release and transport of radioactivity from a solid waste form is by leaching of radioactive isotopes with groundwater. The objective of leach-testing various waste forms is to evaluate the rate at which specific hazardous radionuclides migrate from waste if and when the waste form comes in contact with groundwater. In this paper, measurement of leach rates of radioactive waste by a method which incorporates neutron activation is described. 

Chlorine-36 is an isotope that can be measured by specialized laboratories and its sample collection in the field is simple. It is a radioactive isotope with a half-life of 3 x 105 years, making it useful for groundwater age determinations in the range of 105-106 years. 

The decay of radioactive isotopes created in the earth s atmosphere by the interaction of cosmic rays with atomic nuclei of atmospheric constituents. After such nuclei (e.g., 3H as 3HH0 or 14C as 14C02) are removed from the atmosphere, e.g., fed into a groundwater system (3H) or built into a living organism (14C), their number decreases according to the law of radioactive decay. 

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