DOCUME,NT DOES NOT P Reviewed ~Y~ ‘&5szdz CONTAIN ECI ,,! ./ Date d+%+ 409867 DETERMINATION IN OF TRANSUFUiNIC SURFACE SOIL AT CONCENTRATIONS ENEWETAK The concentrations of transuranic radionuclides (Pluto-.240 and Americi~m-241) in SUrfaCe nium-238, -2391 soils are determined using a sequence of procedures involving instrumental surveys, radiochemical analyses of soil samples, and statistical analysis of the data to estimate the average col~centrations of transuranics in the soil. lm in-situ radiometric survey of the area under investigation is performed using a unique, self-propelled instrument system called an “IMP” (named for the small tracked vehicle that carries the system) . Gamma radiation from the ground is detected by a planar intrinsic germanium detector suspended from the end of a retractable Gamma spectra frcm the detector are boom on the Ii@. From the 60 keV gamma~ the average analyzed and recorded. concentration of Arr-241 in the top 3 cm of soil within the detector’s field of view (a 21-meter diameter circle) is determined. Soil samples are taken and radiochemically analyzed in the The concentrations of Enewetak Radiation Laboratory. Conversion factors Plutonium and Ar.ericium are determined. are derived from these data which allow estimates of the total transuranic concentrations in soil to be calculated from the Am-241 measurements of the o