134Cs/137Cs Activity Ratio in the Biosphere from 1956 Until 1966

Abstract

134Cs and 137Cs activities were measured in samples of lichen, moss, and reindeer meat collected in Sweden. The 134cs/137cs activity ratios in vegetation coincide within the experimental uncertainty with those for reindeer meat, the values being 1958 (4%), 1959 (3%), 1960 (2%), 1961 (1.5%), 1962 (1.0%), 1963 (0.5%), 1964 (0.25%), 19.65 (0.15%), and 1966 (0.11%). 7-ray spectra from the annually performed whole-body measurements on Lapps were analyzed and the 134Cs/137Cs ratios found were: 1962 (1.3%), 1963 (0.9%), 1964 (0.5%), and 1965 (0.3%). The total global injection of 134Cs was estimated to be about 200 kCi up to 1958, insignificant during 1959-1961, and about 50 kCi during 1961-1962. Since 1962 no significant injection of 134Cs was detected. Different ways of generating 134Cs were considered.