Characterization of the TE-NORM waste associated with oil and natural gas production in Abu Rudeis, Egypt E.M. El Afifi * , N.S. Awwad Analytical Chemistry Department, Hot Laboratories Center, Atomic Energy Authority, Post Office No. 13759, Cairo, Egypt Received 22 May 2004; received in revised form 7 November 2004; accepted 17 November 2004 Abstract The present study was conducted to characterize the Technically Enhanced Naturally Occurring Radioactive Materials (TE-NORM) waste generated from oil and gas production. The waste was characterized by means of dry screening solid fractionation, X-ray analysis (XRF and XRD) and g-ray spectrometry. Sediment of the TE-NORM waste was fractionated into ten fractions with particle sizes varying from less than 100 mm to more than 3 mm. The results showed that the TE-NORM waste contains mainly radionuclides of the 238 U, 235 U and 232 Th series. The mean activity concentrations of 226 Ra (of U-series), 228 Ra (of Th-series) and 40 K in the waste samples before fractionation (i.e. 3 mm) were found to amount to 68.9, 24 and 1.3 Bq/g (dry weight), respectively. After dry fractionation, the activity concentrations were widely distributed and enriched in certain fractions. This represented a 1.48 and 1.82-fold enrichment of 226 Ra and 228 Ra, respectively, in fraction F8 (2.0–2.5 mm) over those in bulk TE-NORM waste samples. The activity ratios of 238 U/ 226 Ra, 210 Pb/ 226 Ra, 223 Ra/ 226 Ra and 228 Ra/ 224 Ra were calculated and evaluated. Activity of the most hazardous radionuclide 226 Ra was found to be higher than the exemption levels established by IAEA [International Atomic Energy Agency, 1994. International Basic Safety Standards for the Protection against Ionizing Radiation and for the Safety of Radiation Sources. GOV/2715/94, Vienna]. The radium * Corresponding author. Tel.: C2055 3654299; fax: C202 4620806. E-mail address: eel_afifi@hotmail.com (E.M. El Afifi). 0265-931X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.jenvrad.2004.11.001 Journal of Environmental Radioactivity 82 (2005) 7–19 www.elsevier.com/locate/jenvrad