John C, Clark he July 11, 1951 Sequence of Detonations At the mecting of Dr. Warren's committce rhich was hcld here in May, it was decided that Operation Jangle would open with the deep underground shot. This particular shot was added to the plan of the operation purcly as a method to determine the safety of the succeeding shots, It was the major premise of this committee that such a shot would be the safest of the three, in that the radioactive cloud would be contained by surrounding mountains, After considering this matter carefully, we fcel that this is a false assumption and that in all probability the deep underground shot could be the most dangerous of the lot. Basing my personal opinion on the calculations made by Gaelen Felt and on various conversations and discussions with Jerry Suydam, Bill Ogle, members of H-1l, and others, I am satisfied that the deep underground shot would probably be the most dangerous of the three, and that it could under proper conditions deposit dangerous amounts of activity in populated areas, I realize perfectly well that such an opinion cannot be proven beyond doubt by any calculations done so far, but I feel strongly that firing the deep undergrounc shot represents 2 nossible risk to surrounding population and livestock; and that should things go wrong, it could jeopardize the cntire future of the Nevada Test Site. Personally I would be willing to accept this risk if I fclt that the detonation were essential from a scientific or military point of view. It is my understanding, however, that while the D. 0. D. and others have accepted the inclusion cheerfully, this particular detonation was tossed in purely as a radiologic safeguard, For this reason, therefore, it is my personal recommendation that the deep underground shot be eliminated from Opcration Jangie, and that the surface detonation be fired first. /Original signed by ‘thomas L. Shipman, M.D./7 T. L. Shipman, M.D. Health Division Leader TLS/es Distribution: P,S. John C,. Clark T. Ne White H-Div, File I should not forget to - cy 1A cy 24 cy 3A add the opinion which is generallyheld here, and to which I subscribe, that the exposures permissible for the general population beyond the 40 mile radius, which were proposed by Dr. Failla and incorporated in Dr. Warren's report of the meeting here, simply arc not realistic. It would cause me personally very little concern if some of these people should by chance receive as much as 5 or 10 r total dose. I would not anticipate oxposure of this magnitude, but if conditions were right, a dose of 2 or 3 r might not be surprising. I would consider evacuation if the estimated total dose scemed to be somewhere betwcen 25 and 50 r, provided we could be certain that such cvacuation would not serve to increase the exposure rather than decrease it. Fs eintaRRNI? Snr por ARCHIVES &