Formerly utilized MED/AEC sites remedial action program: radiological survey of the Building Site 421, United States, Watertown Arsenel, Watertown, MA. Final report

This report contains the results of surveys of the current radiological condition of the Building Site 421, United States Arsenal Watertown, Watertown, Massachusetts. Findings of this survey indicate there are four spots involving an area of less than 6000 cm/sup 2/ of identifiable low-level residual radioactivity on the concrete pad which is all that remains of Building Site 421. The largest spot is approximately 5000 cm/sup 2/. The other three spots are 100 cm/sup 2/ or less. The beta-gamma readings at these spots are 8.4 x 10/sup 2/ dis/min-100 cm/sup 2/, 2.2 x 10/sup 5/ dis/min-100 cm/sup 2/, 2.2 x 10/sup 5/ dis/min-100 cm/sup 2/ and 8.5 x 10/sup 4/ dis/min-100 cm/sup 2/. No alpha contamination was found at these locations. Gamma spectral analysis of a chip of contaminated concrete from one of the spots indicates that the contaminant is natural uranium. This contamination is fixed in the concrete and does not present an internal or external exposure hazard under present conditions. A hypothetical hazard analysis under a conservative set of assumed conditions indicates minimal internal hazard. The highest End Window contact reading was 0.09 mR/h. None of the other three spots indicated an elevated direct reading with the End Window Detector. Radon daughter concentrations were determined at three locations on the Building 421 pad. These were 0.00013 WL, 0.00011 WL and 0.00009 WL. According to the Surgeon General's Guidelines found in 10 CFR 712, radon daughter concentrations below 0.03 WL do not require remedial action in structures other than private dwellings and schools. Soil samples taken about the site indicate no elevated levels above the natural background levels in the soil. A gamma spectral analysis of a water sample obtained from the storm sewer line near the Building 421 pad indicates no elevated radioactivity in the sample. It was therefore felt that no contamination is present in this sewer