Statistical design and analysis of environmental studies for plutonium and other transuranics at NAEG ''safety-shot'' sites

This paper is centered around the use of stratified random sampling for estimating the total amount (inventory) of 239-240Pu and uranium in surface soil at ten ''safety-shot'' sites on the Nevada Test Site (NTS) and Tonopah Test Range (TTR) that are currently being studied by the Nevada Applied Ecology Group (NAEG). The use of stratified random sampling has resulted in estimates of inventory at these desert study sites that have smaller standard errors than would have been the case had simple random sampling (no stratification) been used. Estimates of inventory are given for 235U, 238U, and 239-240Pu in soil at A Site of Area 11 on the NTS. Other results presented include average concentrations of one or more of these isotopes in soil and vegetation and in soil profile samples at depths to 25 cm. The regression relationship between soil and vegetation concentrations of 235U and 238U at adjacent sampling locations is also examined using three different models. The applicability of stratified random sampling to the estimation of concentration contours of 239-240Pu in surface soil using computer algorithms is also investigated. Estimates of such contours are obtained using several different methods. The planning of field sampling plans for estimating inventory and distribution is discussed. (auth)