FOREWORD In the preparation of this report, cognizance has been taken of the reports of the Commander, Joint Task Force SEVEN to the Joint Chiefs of Staff per- taining to Operation CASTLE. Although the JTF reports are comprehensive in scope, it is believed that their composition is, in general, directed toward mili- tary and scientific channels of thought. In addition, the JTF reports are thought to lack pertinent information on certain AEC activities and costs useful in evalu- ating various aspects of an operation and in planning for future operations. Therefore, in order to derive maximum benefit from experience gained during an operation, it has been concluded that a supplemental report, embodying only that amountof technical detail essential to an understanding of results and with certain data presented in a manner conducive to useful analyses of proving ground development, would prove decidedly beneficial. This report attempts to achieve these aims in a manner as brief and concise as clarity will permit.