in the early thinking with regard to Proving Ground expansion. Be-~ cause an increased number of high-yield detonations was contemplat- ed for CASTLE, thought was prominent from the beginning with reference to the blast risks to base facilities investment on Eniwetok and radiation risks to personnel, If Eniwetok only were utilized for future high-yield detonations, camplete evacuation of personnel and much valuable equipment would be necessary. Such proved to be the case for MIKE shot of IVY when the actual evacuation of Eniwetok required a major and costly Task Force effort at a most critical perdod. In short, as the study of Proving Ground expansion progressed each successive consideration pointed more and more to the practicability of utilizing Bikini and making CASTLE a two-atoll operation. On 12 September, Dr. Graves presented to AEC a formal justification for the use of Bikini as a supplement to Eniwetok. AEC, while approving the plan in principle and authorizing an initial survey of the atoll, noted that there were no budgeted funds for the work. With this condition in mind, AEC insisted that planning should envisage simplicity and austerity in facilities and stipulated that there would be no permanent construction at Bikini and that in every instance maximum economy would be exercised, AEC approval of the use of Bikini for CASTLE became known beforethe end of September and Hon. Gordon Dean, the Chairman of the Commission, had written a letter on the subject to Hon. Robert LeBaron, the Chairman of the Military Liaison Committee (MLC) to AEC. Mr. Dean pointed out all those cogent arguments which had been