RADIOLOGICAL CLEANUP OF ENEWETAK ATOLL late December 1948 following the relocation of the dri-Enewetak t Ujelang Atoll. The construction work was performed by U.S. Army elements of the JTF.76 Because of the lack of ground facilities on the atoll, the Task Force was quartered on and operated from U.S. Navy vessels. Three nuclear devices were detonated in this operation. Each was placeg on a 200-foot-high tower on one of three separate islands. The first shot, ae eR A 42 code named X-ray, was conducted on Enjebi on |4 April 1948, with a yield of 37 KT. The next test, Yoke, took place on Aomon on 30 April, with a yield of 49 KT. The last, Zebra, was carried out on Runit on |4 May, witha yield of 18 KT. Details of devices tested and of test results remain classified at this writing. ?? CONSTRUCTION ACTIVITIES Operation Sandstone established a pattern that was to be followed in other test series. That pattern was: a rehabilitation phase in which existing facilities were readied to support the upcoming operation; a construction phase devoted to providing support and scientific requirements; an execution phase for actual testing, and a roll-up phase during which the atoll was made secure and preserved for further use. Figures 1-38 through 1-41 show construction activities on various test and test support installations. The activities shown occurred at various times in the test program. The construction and development work on Enewetak Atoll in support of Operation Sandstone was carried out by U.S. Army construction units with civilian contractor assistance. The construction phase consisted of: a. Developing Enewetak Island as the administrative and logistic base for all atoll operations. b. Developing Medren as the scientific and technical control and coordinating center for all atoll operations. c. Developing construction camps on islands either on or near the islands on which tests were to be conducted. d. Constructing the scientific and technical facilities on the test islands. As time went on, Army construction units had smaller and smaller roles, while those of civilian contractors continued to grow. The AEC decided in mid-1949 to carry out major construction projects on the atoll with the view of providing an adequate support base ashore, with more adequate housing and technical facilities. A survey had previously been made by Holmes & Narver, Inc. to determine the existing conditions and the additional facilities required. The results were submitted on 7 January 1949, and a design and construction contract was signed in June of that year. ie: - a