Environmental monitoring and dose assessment for a decommissioned reactor, SEFOR, and a radioactive waste disposal site, Harmon Road

Radioactivity concentration of possible fission products and natural background radionuclides in soil and water samples from the decommissioned SEFOR reactor and the Harmon Road low-level radioactive waste disposal site were monitored. Dose assessment for both of these facilities was performed using the ONSITE/MAXI1 computer code based on scenario exposure pathway analysis. Reference concentration levels of nine selected radionuclides in soil were calculated from a reference dose level of 1 mrem/yr.;The optimum counting geometry for the 28% HPGe detector consists of 1800 g of soil in a 2-liter Marinelli beaker. The average LLD for this geometry is 0.0032 pCi/g.;Analyses of the samples using gamma spectroscopy indicate that the seven SEFOR surface soil samples have an average Cs-137 concentration level of 0.14 pCi/g. The surface soil samples from Harmon site have a mean Cs-137 concentration of 0.65 pCi/g. This concentration would yield an annual dose of 0.07 mrem. Cesium-137, which was deposited on the top 5-cm layer of soil from nuclear weapon testing fallout, is only found in surface soil samples. Cesium-137 is not detected in any of the boring soil samples. None of the water samples show any traces of Cs-137, No cobalt-60 is detected in any of the soil and water samples.