title: Concentrations of natural radionuclides in imported mineral substances.
abstract: Levels of natural radionuclides, such as thorium-232 (232Th), radium-226 (226Ra) and potassium-40 (40K), were determined in about 2,000 samples of imported mineral substances using gamma spectrometry. The maximum concentration levels of 232Th, 226Ra and 40K were 1,260 +/- 54, 13,400 +/- 94 and 1,256 +/- 260 Bq kg(-1), respectively, in zirconium compounds. Due to relatively high concentrations of the above-mentioned radionuclides in some imported mineral substances, the National Radiation Protection Department (NRPD), as the competent authority, has established national limits (900 Bq kg(-1) for 232Th, 1800 Bq kg(-1) for 226Ra and 11,000 Bq kg(-1) for 40K), based on the external exposures, for general importation permits of these materials.
authors.affiliation: National Radiation Protection Department, Atomic Energy Organization of Iran, Tehran. ghiassi@mailcity.com
authors.forename: M
authors.initials: M
authors.lastname: Ghiassi-Nejad
authors.forename: M M
authors.initials: MM
authors.lastname: Beitollahi
authors.forename: N
authors.initials: N
authors.lastname: Fallahian
authors.forename: J
authors.initials: J
authors.lastname: Amidi
authors.forename: H
authors.initials: H
authors.lastname: Ramezani
mesh_terms: D003132:Commerce; D004784:Environmental Monitoring; D008903:Minerals / Q000737:chemistry*; D011640:Public Policy; D011868:Radioisotopes / Q000032:analysis*; D012016:Reference Values; D012990:Soil Pollutants, Radioactive / Q000032:analysis
chemical_list: D008903:Minerals; D011868:Radioisotopes; D012990:Soil Pollutants, Radioactive