Instead, DoE measured the gamma radiation emitted by americium--a daughter product of plutonium. Americium results from radioactive decay of plutonium, and its gamma emissions are sufficiently energetic to penetrate several inches ofsoil. To accomplish this measurement in the difficult environment on Enewetak, DoE designed and built special tracked vehicles which could operate in the soft sands, equipped them with boom-mounted, highly sensitive germanium detectors (cooled by liquid nitrogen), and installed analysis and counting equipment in the vehicle. The vehicle itself was air conditioned to provide a controlled environment for this delicate equipment. These mobile measuring systems measured the intensity of gamma radiation in the energy spectrum characteristic of americium. Readings were taken at every intersection of a 50-meter grid surveyed on each island which coarser aerial and in-situ surveys had shown to have significant transuranic contamination. At each location of van readings, soil samples from several depths were obtained and were analyzed for plutonium-americium ratio by the radiological laboratories. In areas of higher or irregular contamination, additional van readings and soil samples were taken at intervals of 25, I2%, or 6% meters. Sophisticated computer programs were developed to produce radiation contour maps of pluto_nium contamination, which were then used by cleanup teams to guide soil excision. After each removal of soil, the area was re-surveyed, new van readings and new soil samples were taken, until residual plutonium contamination had reached acceptable limits. The U.S. forces which accomplished the radiological cleanup and rehabilita- tion throughout 1978 and 1979 typically were present in about the following groups and strengths: . Joint Task Group Staff (DNA) 35 Army Element 430 Navy Element HS Air Force Element 75 Support Contractor 165 Army & Air Force Exchange System 5 DoE 5 Rad-Lab Contractors 10 Mid-Pacific Research Laboratory 10 Dol and TTPI 5 Rehabilitation Contractor _100 Micronesian Labor 10 965 7 . -