Semiquantitative Measurement of Fission Produced Gamma Ray Radioactivity in Soils at Dubuque, Iowa

Residual fission-product radionuclide contamination (fallout) in soils at Dubuque, Iowa was evaluated with an Exploration geometrics gamma ray scintillometer in 1985 and after the Chernobyl accident in 1986. Anomalous amounts of gamma ray radiation were found near where downspouts discharged storm runoff from the roof of a dwelling. The 1985 residual cesium-13 7 activity in the soils of the area was found to be 0.2 pCi/gram with an areal contamination of 16 ± nCi/m2. Activities associated with the soils near the discharge points of the downspouts ranged as high as 8 pCi/gram. This contamination seems to have occurred prior to 1970 and most probably during the period 1945 to 1963. The Chernobyl accident resulted in an additional soil activity of 0.05 pCi/gram or an areal contamination of 4 ± 0.1 nCi/m2