oxide spheres produced from vapor condensation of structural material used to make the nudear explosive (Crocker, et al., 1965. Radio- nuclides of refractory elements tend to be in the larger particles, while radionuclides of volatile elements tend to be the smaller particles, The particles tend to be of submicron size, and so even local fallout is similar in composition to worldwide fallout from any tests (Heft, 1970, p. 274). Weathering The radioactivity of the fallout remaining on the islands will decrease not only from the natural radioactive decay, but also from weathering effects. Wind can transfer surface deposits of fallout from one location to another. However, after 15 years of this action at Eniwetok Atoll, a significant decrease in radioactivity or repositioning of radioactivity seems unlikely henceforth to result from wind effects, Furthermore, rain can wash the water soluble or loosely adhering radionuclides to deeper depths in the soil, from which depths the soil above would provide some radiation shielding protection for persons being exposed. The amount of this rain-form of weathering, called leaching, depends upon the chemical and structural properties of the fallout particles as well as on climate conditions et al., 1965). (Crocker, Typically, leaching alone would halve the radioactivity over a period of years (Glasstone, 1964, p. 458). For Eniwetok Atoll, the future decrease of radioactivity by leaching is difficult to estimate ~ 11 ne rar:armen:seennemmmene = nn me