Radionuclides cosmic ray-produced

Tihe atmosphere contains many radionuclides which result from nuclear weapons testing and from natural processes. The nuclear weapons-produced radionuclides include both fission products and activation products from the construction materials of the device. The natural radionuclides include the decay products of radon and thoron, the natural radionuclides in the airborne dust, and the cosmic-ray-produced radionuclides which result from spallation reactions in the atmosphere. Through the determination of the absolute and relative concentrations of this wide spectrum of radionuclides, it should be possible to define the rates of both the long term stratospheric processes and the shorter term tropospheric processes. At the beginning of 1962 a ground-level... 

The seasonal variations in the ground-level air concentrations of nuclear weapons-produced and cosmic-ray-produced radionuclides are... 

Short Lived Cosmic Ray-Produced Radionuclides as Tracers of Atmospheric Processes... 

Table I. Half-Lives and Decay Characteristics of the Cosmic Ray-Produced Radionuclides...

Half-lives and decay characteristics of cosmic-ray produced radionuclides... 

Thereafter, cosmic rays were observed and explained, and many cosmic-ray-produced radionuclides were identified. The number of known and characterized radionuclides increased dramatically with the development and application of nuclear-particle accelerators in the 1930s and nuclear-fission reactors in the 1940s. 

Samples that contain approximately 10 radionuclides with intermediate to long (1 day-1 year) half-lives. This mix is found when monitoring distant locations for recent fallout from atmospheric nuclear tests and effluent from waste tanks and stacks at operating nuclear power plants. A subcategory is samples that contain natural radionuclides with half-lives in this range as progeny in terrestrial decay chains and cosmic-ray-produced radionuclides. 

Ingestion and effective doses to an average person by cosmic ray-produced radionuclides (UNSCEAR 1993a)... 

A method for estimating the residence time of tropospheric aerosol particles associated with the cosmic-ray produced radionuclides, such as Be, is based on the aerosol particle growth rate, which is the change of particle diameter with time, which was estimated to be 0.004 to 0.005 pmh (McMurry and Wilson, 1982) and the difference between the activity median aerodynamic diameter, AMAD, of a radionuclide, e.g. Be, and the size of the Aitken nuclei in the size distribution of the aerosol particles, which is 0.015 pm (NRC, 1979). The AMAD of all radionuclides is in the accumulation mode of the size distribution of atmospheric aerosol particles which ranges between 0.1 and 2.0 pm (NRC, 1979 Papastefanou and Bondietti, 1987). 

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