SECRET UNCL SSIFIED ~1175~-AEC =30-53 32 ground would be about 15 hours. If it is assumed that the area c the fall-out from this stem top is proportional to the square of downwind, the area covered would be about 10,000 mi*,- « red by fhe distance If it 4s ¢ ther assumed that if this area contained 50 percent of Mike, there wou id be an average concentration 5.8 wemi” at 15 hours; the time the debris have reached the ground. would The circular srea on Fig. 1 indicates the extent of the area affected. It must be concluced that if such a high average ccncentrati bn Were produced, peak concentrations might be high enough to be exceedinkly dangerous. It can sliso be seen, by superposing Fig. 1 on a chart of the area around Eniwetok, that, if this debris did in fact fall out, no fall-out measurement to detect it. there was The problem of the voria-u}de distribution of Mike debris will take on a vastly different aspec Lb if 50 to 8C percent of the debris fell undetected on the ocean. The pr bolem of radiological safety will also be made much more difficult if plan must be made to keep personnel trom such large areas. state With the presen of ignorance of the reality and magnitude of the fall-out from megaton range bombs, it is necessary to insure that there is proper doc ntation ot the fall-out from future tests. ARDC, (1) Lule jian, N.M., Radioactive Fall-out from Atomic Bombs, Hq., November, 1953. (2) Operation JANGLE, Summary Report: Weapon EvTects Test, Wr—-4il, AFSWP, November, 1952. (3) Operation IVY; Nature, Intensity, and Distribution of Fali-oft from Mike Shot, NRDL, April, 1953. 1045333 ee = : — a HL 1 UNCLASSIFIED LANL