36 RADIOLOGICAL CLEANUP OF ENEWETAK ATOLL OPERATION CROSSROADS: JUNE-JULY 1946 Bikini Atoll was the one chosen as the site of Operation Crossroads, which wasto be the occasion ofthe first peacetime detonations of nuclear | weapons. Theclimatic, wind, current, and harbor size requirements could be met. The selection was influenced by the fact that the population of the atoll was small and could be relocated easily and that Bikini was close to Kwajalein and Enewetak Atolls, both of which held military support facilities. Under the Presidential authority, the Navy also relocated the people of Enewetak to Meik Island in Kwajalein Atoll while the Bikini tests | were being conducted.*4.55 Three tests were planned for Operation Crossroads, two of which— Able and Baker—were eventually carried out. The first of these was an aerial drop, and the second an underwater shot. The bombsweresimilar to those which had been used against the Japanese cities and which had produced yields of 13 KT at Hiroshima and 23 KT at Nagasaki. The yield, stated in KT (thousands of tons), expresses the explosive equivalent of a weight of TNT. For example, a nuclear bomb havinga yield of 25 KT would have the same explosive force as a single explosion of 25,000 tons of TNT. A ‘‘nominal’’ yield was one approximately equivalent . to that of the bombs used against the Japanesecities. Test Able occurred on 30 June 1946. The bomb was dropped from a B-29 aircraft and exploded about 500 feet above the lagoon surface. The bomb detonated 1,500 feet west of the center target vessel. The vessel did not sink, but five other vessels were sunk and others were burned or damaged. The sunken ships were two attack transports, two destroyers, and a Japaneselight cruiser.56 The yield of the nuclear device of Test Able was 23 KT. Test Baker was performed with a nuclear device suspended 90 feet below a landing ship in the center of another array of ships in the lagoon. At detonation, a hollow column of water rose to a height of a mile above the surface of the lagoon. The U.S. battleship ARKANSAS, the aircraft carrier Saratoga, and the Japanese battleship Nagato were sunk, as well as other surface vessels and submarines. Some sank immediately and others .took from 7-1/2 hours to 5 days to sink.5? Test Baker also yielded the equivalent of 23 KT of TNT.*8 Although these tests were successful, Bikini ifself demonstrated a number of deficiencies as a test site. One was the lack of land area, which essa tie use Of oUllace Vessels for planning, administration, scientific laboratory work, and for life support. A second was the combination ofisland orientation and wind direction, which prevented the installation of an adequate airstrip. Descripion and ttistory. 1920-1972 ESTABLISHMENTOF AEC AND AFSWP The passage of the Atomic Energy Act of 1946 resulted in the restructuring of the Manhattan Project organization. Responsibility for future atomic development was assigned to the AEC, a new civilian agency. Most of the Manhattan Project scientific personnel and laboratories went to the AEC. The Manhattan Project itself was renamed the Armed Forces Special Weapons Project (AFSWP) and remained a military organization. The AFSWP has been renamed twice, as the Defense Atomic Support Agency in 1959 and as the Defense Nuclear Agency in 1971. The first head of this organization was Major General Leslie R. Groves, USA, who had directed, the Manhattan Project. He was named Chief, AFSWP on 28 February 1947 and Rear Admiral William R. Parsons, USN, became his deputy. RADM Parsonsalso had participated in the Manbattan Project and was bomb commander aboard the plane, the **Enola Gay,”’ that dropped the first atomic weapon on Hiroshima. He had also served as Commander, JTF-1, at Bikini Atoll.5? The U.S. Army Element of the Manhattan Project at Los Alamos Scientific Laboratory was Company C, Santa Fe Detachment, 38th Engineer Battalion, U.S. Army Corps of Engineers. In the spring of 1947, it was relocated to Sandia Base, near Albuquerque, New Mexico, and established as Field Command, AFSWP, the principal operating element of the project. Later in the year, U.S. Air Force and Navy personnel were assigned, making AFSWP a joint service command. As the central coordinating agency between civilian and military interests in atomic development, AFSWP provided staff and technical assistance to the Secretary of Defense; overall surveillance, storage, and maintenance of the nuclear weapons stockpile; technical, logistics, training and stockpile management support to the Military Services; and, direction of the Department of Defense (DOD) weapons effects test programs. During overseas test operations, JTFs were formed af Sandia Base under the direction of the Chicf, AFSWP. Military Service elements were assigned to the JTF to provide support at the proving grounds.® The first AFSWP JTF was formed under the command of Captain T. A. Hederman, USN, to conduct a resurvey of Bikini Atoll following Operation Crossroads. ®! ESTABLISHMENT OF ENEWETAK PROVING GROUND: SOLT“DECEMDER Meanwhile, action was being taken in the United Nations (U.N.) to place the Pacific islands, which Japan had administered under a League of Nations mandate, under the trusteeship of the United States. In