Fallout ground level

Figure 5. Variation of the number of single fallout particles, 141Ce and 141Ce/144Ce ratio in the ground-level air at Fayetteville, Ark. (1)...

Observed Fractionation in Ground Level Fallout from Three Nuclear Cratering Detonations... 

A. Types of Surveys. Various types of radiological surveys may be performed. Area surveys may involve the determination of fallout patterns on the ground, levels of airborne activity, or contamination patterns on ships or in buildings. Personnel surveys are performed to detect the presence of contaminated material on the body s surfaces, in body openings, e.g., nose and ears, or in the case of casualties with traumatic injury, contamination in wounds. The results of personnel surveys are used to evaluate health hazards and to establish decontamination requirements. Equipment/material surveys are conducted primarily to establish requirements for decontamination. Monitoring should be done with consistency (1-2 cm from surface for alpha and beta and 1 meter from surface for gamma). 

The second measure deals with the deposition rate of material at the earth s surface. Deposition is measured i terms of the rate of accumulation per unit area per unit time (mg/m -day). It may take place by several processes dry fallout, absorption, or wet deposition associated with dew or precipitation. Because of the potential for certain long term ecological effects and degradation of buildings, deposition as been an important measure of pollution in Europe (e.g., OECD ). In principle, the deposition rate of material at the ground can be related to the ground level concentration by the formula ... 

It is at present somewhat uncertain if very low levels of radiatirm are harmful. We cannot avoid all radiation since there is a natural radiation background (with approximate yearly exposure) due to, for example, the cosmic rays (40 millirem at sea level, 250 Rem at 500 m elevation) radium and radon in ground and building material (40 Rem) and potassium 40 (18 Rem). In addition, we can add some man-made radiation sources such as one chest X-ray (40 Rem), one dental X-ray (20 Rem), fallout from nuclear explosions (5 Rem), as well as miscellaneous sources such as TV, CRT, etc., all of which total to 163 Rem/year (for sea level). The average annual radiadmi dose to a nuclear reactor worker in Ontario is 0.68 Rem with an annual limit of 5 Rem set by radiation protection regulations. 

Surface burst a nuclear weapon explosion that is close enough to the ground for the radius of the fireball to vaporize surface material fallout from a surface burst contains very high levels of radioactivity... 

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