Atmospheric Dispersion of Radionuclides

Man-made radionuclide release has been a topic of division for as long as man has worked with known, hazardous nuclear material. The destructive and invasive nature of spontaneously fissioning isotopes makes them of particular interest to us humans. We must protect against any large, harmful release whenever possible, and should seek to immobilize radionuclide inventories which we know of. This was not always the case, as when early nuclear scientists began their work, not many of them understood or took precaution to prevent these issues.

I'm not too well versed in atmospheric dispersion although I find maps of nuclide release to be intriguing. Nuclear accidents can cause a slew of nasty emitters to be scattered across the world. For this reason it is imperative for the global nuclear community to understand the negative side effects of nuclear-related incidents. This image given by NOAA is one misleading figure - this is what comes up when you search "radiation dispersion in the atmosphere" in Google:

http://media.independent.com/img/photos/2014/03/26/radioactive-water.jpg 

Modeling the transport and fate of radionuclides in the environment is a critical problem for many applications. One paper written on geomorphology attempts to show a robust relationship with their inverse correlation used and point-based calibrations to predict diffusivity values across the landscape. Another describes their diffusion in concrete and soils and the problem of encasement failure for its effect on mobilization via water intrusion. Specifically, Technicium and Iodine were analyzed and it was found that there is great importance in ensuring little to now moisture in the sedimentary waste environment. Pacific Northwest National Laboratory and other national labs have done extensive leaching and diffusion testing for waste products.

Much of the quantitative analysis is based on Fick's law and diffusivity parameters. Each of the investigations above varied parameters like carbonation, concentration, material thicknesses, etc. and tried to determine the effects those variations had on the likelihood of release. The results from these analyses are presented with figures of merit and can impact the policies which regulatory oversight implements.


References:
http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-20683.pdf