28 DISTRIBUTION OF RADIOACTIVE DEBRIS WORLDWIDE EFFECTS OF ATOMIC WEAPONS Fallout in the United States from TUMBLER/SNAPPER The TUMBLER /SNAPPER fallout was measured during the period from April 1 to June 18, 1952, at ninety-two stations spread over the United States. The last test of the TUMBLER /SNAPPER Series was on June 5, 1952. The fallout measurements for each 24-hr period were extrapolated to January 1, 1953, and were totaled. The maximumtotal for any station was 14,000 d/min/ft™ at Elko, Nevada, and the minimum was 86 d/min/ft? at North Head, Washington. The average obtained by adding the totals for all stations anddividing by the number of stations was 1511 d/min/ft’. Since the stations were by no means uniformly distributed, a better avetage was obtained by averaging the fallout bystates, weighting the average for each state by its area, and computing the weighted average for the United States. This weighted average was 1750 d/min/ft?. Where the there were no stations in a state, or only one or two, the average for state was obtained by averaging in the fallout from the nearest stationscircumscribing the state boundaries. The smallest average was 270 d/min/f£t? for both Louisiana and Mississippi. The greatest was 6585 d/min/ft’” for Idaho, and Nevada and Utah were second and third with 6333 and 6167, respectively. Since er (5280)? 1 d/min/ft 39% io” x GO = 1.256 & 10° su: » curies/mt’, the average fallout from TUMBLER/SNAPPER extrapolated to January 1, 1953, was 1750 & 1.256 X 10°, or 2.20 * 10° curies/mt’. The total @ activity, as of January 1, 1953, which fell out over the United States (area — 3 X 10° mi) is then 2.2 107 "i9* x3 xX 10," or 6.6 X 10? B megacuries B ( (Mc). ) Worldwide Fallout from TUMBLER /SNAPPER Fallout from TUMBLER /SNAPPER has been extrapolated to January 1, *Disintegrations per minute per square foot. 29 1953, for fifteen stations outside the continental United States. Six of these stations reported fallout for the entire TUMBLER/SNAPPER period. The other nine were activated too late to record fallout from the first 3 TUMBLER/SNAPPER shots but did report for shots 5 through 8. The area covered is roughly from 80° W to 15° E longitude and from 60° N to 35° § latitude. The average of the six stations reporting for the full period is 254 d/min/ft®. For the nine stations reporting a portion of the shots, the average is 110. The weighted average for the fifteen stations is 212 d/min/ft?, or 212 X 1.256 X 10° = 2.66 x 10° B curies/mi’. The area between 80° W and 15° E longitude and 60° N and 35° latitude is A 0.5736 ) = 520 x 10 » ( 0:8660 + 197 10° ( cos30°+2 cos55°) ) __ 360 ye == 52.0 K 10° K 0.7198 =~ 37.4% 10° mi? and 2.66 X 10° & 37.4 X 10°=9.95 X 10% 8 Mc. The total for the (37.4 + 3) X 10° mi? = 40.4 X 10° mi? outside the immediate fallout area is 0.066 + 0.0995 == 0.165 Mc. The close-in fallout for each shot of the TUMBLER/SNAPPER series must be estimated on the basis of yield and height of burst. The foal activity from each shotis given from the following derivation: The f-ray activity from a 20-KT bombis 8.2X_10%* ya B particles/sec, at time ¢ seconds after the explosion.‘ The number of 8 megacuries per kiloton (KT) at a time ¢ days after an A-bomb explosion is then ___ 8.2*_10"* 10% 30 & 3.7 <x *F -1.2 ’ or 1.108 X 10’ X #"? Mc/KTat ¢ seconds after the explosion; or, for t in days, the number of megacuries per kiloton fs 1.108 x 10° — 13 ar? (864001) ** 0