Results of the outdoor radiological survey at the Portsmouth Gaseous Diffusion Plant site, Piketon, Ohio

The Portsmouth Gaseous Diffusion Plant (PORTS) is owned by the US Department of Energy (DOE) and managed by Martin Marietta Energy Systems, Inc. As shown in Fig. 1, the plant is located in sparsely populated, rural Pike County, Ohio. PORTS began in 1952 as part of the Atomic Energy Commission's (AEC) proposed expansion of the gaseous diffusion program in order to increase the production of enriched uranium. The 3,708-acre site is about a half mile east of US Interstate 23 (Fig. 2) and approximately 1 mile east of the Scioto River Valley (Fig. 3). The current layout of the plant is shown on Fig. 4. The principal site process is the separation of uranium isotopes 235U and 238U through gaseous diffusion. This uranium enrichment process involves the more rapid diffusion of lighter molecules of UF6 (uranium hexaflouride) through the barrier walls of a porous tube. The end result is a UF6 stream that is slightly enriched in the 235U isotope. The separation process is repeated in a cascade arrangement until the desired concentration is reached. At the request of the PORTS Environmental Safety and Health Division, the Health and Safety Research Division (HASRD), Oak Ridge National Laboratory (ORNL), conducted a radiological survey of the outdoor surface environment of the PORTS site. The surveyed area covered approximately 150 acres of fenced ground consisting of dirt, asphalt, and concrete. The survey was performed between July 1990 and April 1991, and the results reported to PORTS, Health Physics Department. The survey purpose was to determine the extent of radiological contamination and to locate and prioritize areas of concern from both a worker health/safety and an environmental standpoint. Specifically, the objectives of the survey were to assess the areal radioactive status of the site and to analyze surface soil samples for the presence of selected radionuclides. The principal radionuclide of concern is uranium