Applicability of 1994-1995 USRADS{reg_sign} surveys of Bear Creek Valley flood plain and Operable Unit 1 to the radiological characterization of Y-12 grassy/wooded areas

This document, provided in support of the Y-12 Site Radiological Characterization Study, analyzes the utility of data from two reports by Chemrad Tennessee Corporation in identifying radiological contamination in excess of contamination control guidelines at the surface of soils in the Bear Creek Valley Flood Plain (BCVFP) and in Y-12 Operable Unit 1 (OU1). The Chemrad reports were developed under subcontract to Science Applications International Corporation for their remedial investigation of these sites for Martin Marietta Energy Systems Environmental Restoration Division. Surveys were performed by Chemrad using the UltraSonic Ranging and Data System (USRADS{reg_sign}), which utilizes ultrasonic triangulation to determine the location of a survey technician at the same time that radiological monitoring data are telemetered from his instruments to a remote receiving station. Floor monitor and Geiger-Mueller pancake meter results from the USRADS{reg_sign} surveys are shown to be sufficiently precise to reliably detect contamination in excess of the limiting radioactivity value of 1,000 dpm/100 cm{sup 2} for removable uranium contamination specified in 10 CFR 835 Appendix D. MicroRem meter survey results, also included as part of the USRADS{reg_sign} surveys, indicate that the derived limiting value of 56.8 {mu}rem/h for penetrating dose at 1 m (corresponding to 100 mrem/{gamma}) was not exceeded. However, both the pancake meter and floor monitor results suggest that surface contamination exceeding 1,000 dpm/100 cm{sup 2} is not uncommon. Sites in OU1 and BCVFP were visited, and independent surveys made with hand-held instruments, to confirm conclusions about the USRADS{close_quote} survey results and to verify that these results are from contamination uniformly distributed on the soil surface, and not from discrete sources which are not likely transferred to shoes, vehicles, or clothing