Typical total external average radiation exposure rates, in the southern islands are less than one microroentgen per hour. The exposure rates for the northern islands are higher, as one would expect from test history. These levels range from total external average exposure rates of 5 microroentgen per hour to around 100 microroentgen per hour. As a matter of interest, external exposure rates in the United States from natural background ranges 6 to about 10 microroentgens per hour. 60, The primary radioactive isotopes are cesium-137, cobalt- strontium-90, and tranSuranic elements (plutonium and americium). The former isotopes are relatively short-lived: whereas the transuranic elements are long-lived. The primary purpose of the radiological soil cleanup is to reduce the transuranic elements to levels that do not pose long-term hazards to the returning people of Enewetak. Of course, in removing soil which contains transuranics, any other radioisotopes present will also be removed. , Service personnel who have the potential for being exposed to radiation consist only of those who are actually engaged in the removal and disposal of the contaminated debris, structures, and soil. Typical duties involve operating bulldozers, backhoes, trucks, cranes, cement mixers, and boats. The attached Operation Plan will provide a basic understanding of the overall effort. Of the 650 DoD personnel on the Atoll, possibly 400 have the potential for being exposed to radiation. The overall philosophy is for operations to be conducted in such a manner as to assure that radiation exposure to individuais is limited to the lowest levels practicable. The cleanup radiation exposure standards are based on Title 10, Code of Federal Regulations, Part 20, as implemented in Department of Army Regulation 40-14, Control and Recording Procedures for Occupational Exposure to Ionizing Radia- tion. The limits for exposure in this regulation are 5 rem per year, or 1 1/4 rem for any three consecutive months. The basic standard operating procedures for the cleanup radiation safety program were prepared by a group of experts from DNA, DoE, Sandia Laboratories, Los Alamos Scientific Laboratory, and Lawrence Livermore Laboratory. The program ’ is implemented in the field by a specially trained group of Air Force personnel organized into-Field Radiation Support Teams. These teams are under the supervision of radiation safety experts in the Radiation Control Division of the Joint Task Group on the Atoll. ng Te EE cee dere ee mene ee ot ~ An on-site Radiation Control wo