” _ Uy U.iTsd STATS aTC..1o SNSRGY COMISSION wisnington 25, Dd. C. Tel. ST 3-600 mat. 307 FOR RSLSASE 2:30 F.M. (EDT), FRIDAY, OCTOBER 12, 1956 Remarks Prevared by Dr. Willard F. Libby, Commissioner United States atomic Enargy Commission For Delivery befora the American Association for the Advancement of Science, Washington, D. C. Friday, October 12, 1956 CURRSNT RESEARCH FINDINGS ON RADIOACTIVE FALLOUT I. iwTRODUCTION The radioactivity produced by the fission reaction, being due to a rifstira of many different fission prouucts, changes its charact2ristics continuously and radidly following release by the bomb detonation. So, the conditions of firing are of extreme importance in determining the fallout effects. The intensity of radiation is enormously greater soon after the detona- tions, decreasing about tenfold for every sevenfold incrsxs2 in age. Since the time required for ingestion into the body is long, ingestion is unlikely for the snorter-lived fission vroducts end therefore the princical hazards for close-in fallout are radiation exposures by gamma radiaticn of the whole body and by beta radiation on the sxin. In the Longer times, weeks and months after the explosion, the ingestive hazards begin to become (more)