found in ae #3 and #4 indicates - the radexes prepared using the actual winds three hours.before shot time, delineate the general fall-out area adequately. In Mygures 1 through 9 the radex plots based on the H-3 and H-< hour actual winds are superimposed on the actual fall-out area. A study of these figures shows clearly that radex plots based on the actual winds near shot time delineate the fall- out area adequately. The area of maximum intensity of fall-out could be located by this method within an averages angular displacement of roll plus or minus five degrees, The angular displacement of the center of the maximimfall-out area does not show a displacement greater than 15 degrees. Considering that the :inds are four hours old in these radex plots, it becomes at once evident that there is considerable persistence to the winds. Certainly if the decision to fire a potentially contamin- ating shot is delayed until the last two or three hours, it is difficult to see how larce errors could be made in the radex plots, Fortunately onan i it appears that the simple Stokes’ Law assumptions are valid for 70 to 150 micron particles, which are the main cause of the radioactive con- cinattaeeittinatmriat ination, tpilbeesinateinies tamination within 200 miles of the domestic test site at the Nevada Proving Grounds, B, Verification of Radioactive Fall-out Forecasts After the writer had analyzed the fall-out from TUMBLER/ SNAPPER (R) tower shots it was possible to forecast tha‘: 10 to 15 XT bombs detonated from 300 ft towers would produce § to 2 roentgen life time doses within the populated areas in the periphery of the Nevada Test Site, This information was made a matter of record and called to ,eo4 UNCLASSIFIED nal ae tae C3-3 ~~ - anole > edag”