ABSTRACT
During periods of weapons testing at the Nevada Test Site (NTS) between 1951 and 1958, the Environmental Measurements Laboratory (EML) monitored daily fallout at about 100 sites in the U.S. using gummed-film collectors. These gummed-film data represent the only comprehensive set of actual measurements of fallout during this period for areas outside the immediate vicinity of the NTS. The measured beta activities originally reported by EML have been reviewed and reevaluated. This reevaluation corrected a number of errors in the original data set and allowed fairly accurate estimates to be made of specific radionuclide depositions from individual NTS shots. Estimates of the geographical and temporal variations in cumulative 137Cs and 131I depositions from all NTS shots through 1957 are presented, as well as estimates of the relative impact of particular shots and test series. The revised gummed-film estimates of total NTS fallout depositions are compared with estimates based on contemporary and historical soil sample analyses. These reevaluated gummed-film fallout deposition estimates are being extensively utilized in a number of ongoing programs to reconstruct the radiation exposure of the U.S. population from Nevada weapons testing.
Subject(s)
Environmental Exposure , Nuclear Warfare , Radiation Monitoring/instrumentation , Radioactive Fallout/analysis , Cesium Radioisotopes/analysis , Film Dosimetry , Humans , Iodine Radioisotopes/analysis , Nevada , United StatesABSTRACT
Calibration factors to convert a measured full-absorption peak count rate to activity in the soil and dose rate in air are given for Ge detectors that are used for field measurements of radionuclides. The appropriate factors for a given detector are derived using three primary parameters: the manufacturer's quoted efficiency at 1332 keV relative to a 7.6 cm (3 in.) long by 7.6 cm (3 in.) diameter NaI(Tl) detector, the detector's orientation in the field (up or down) and the Ge crystal length/diameter ratio. The accuracy of the results obtained by using this simplified calibration technique is estimated to be 10-15%.
