RADIOLOGICAL CLEANUF Ur BINBWhLANK ALULL toe ee Re eee LIER IOH UME ETBSIUIV, AUR 1g FIGURE 1-56. CRATERS RESULTING FROM MIKE AND KOA EVENTS (SEMINOLE CRATER IN THE BACKGROUND). wv? life of 5.3 years. b. Strontium-90, an emitter of beta rays, with a half-life of 29 years. c. Cesium-I37, an emitter of gamma rays and beta particles, with a halflife of 30 years. d. Plutonium-239, an emitter of alpha particles, with a half-life of 24,000 years. e. Plutonium-240, an emitter of alpha particles with a half-life of 6,600 years. f. Americium-24l, an emitter of gamma rays with a half-life of 433 years. In addition to the radionuclides present in the soil and lagoon sediments of Enewetak Atoll, other radioactive materials were present on some of the islands in the form of contaminated debris. Some of this debris was on the surface and some was in burial sites on certain islands. All of these evidences of the nuclear test program were to have some influence on the cleanup operation. In chapters to follow, the condition of each individual island is described. These descriptions are based on the conditions of the island in 1977, almost 20 years after the last test shot was fired and before any cleaning operations had begun. WESTERN TEST RANGE: 1958 - 1972 The years between the termination of the nuclear weaponstest program and the commencement of cleanup planning were not without activity. For a short time, the atoll lagoon was used as a target arca for missiles fired from Vandenberg Air Force Base in California. Later, that function was transferred to the much larger lagoon of Kwajalein Atoll. In the 1960's, explorations and experiments on the upwelling of deep-ocean water were conducted by the University of California at San Diego. Neither of these operations had much effect upon the effort that would be required in the cleanup project, although some structures were erected to provide operations and maintenance support. wee 58 PROJECT HIGH ENERGY UPPER STAGE (HEUS) Toc FIGURE 1-57. SEMINOLE CRATER ON BOKEN. Force, two test firings of a developmental HEUS rocket motor were conducted. One was conducted in 1968 and the other in 1970, both on Enjebi. The rocket motors tested each contained 2,500 pounds of propellant of which 300 pounds was beryllium. The first firing, in April