title: Natural radioactivities in iron and nickel ores imported into Japan and the dose assessment for workers handling them.
abstract: Japan imports Fe and Ni ores from abroad for use as industrial raw materials in the manufacture of industrial products like stainless steel. Some of these ores might contain high levels of radioactivity, and then workers handling them would be exposed to radiation without being aware of it. Activity concentrations in these ores should be measured to evaluate the radiation exposure of workers. In this study, Fe and Ni ores used as industrial raw materials were collected from iron and steel companies, and the activity concentrations of the (238)U series, the (232)Th series and (40)K in these ores were determined using inductively coupled plasma mass spectrometry (ICP-MS) and gamma ray spectrometry. The activity concentrations of the (238)U series, the (232)Th series and (40)K in these ores samples were lower than the International Atomic Energy Agency (IAEA) values. The doses to workers handling these ores were estimated using methods for dose assessment given in a report by the European Commission. In each scenario, a maximum value of the annual effective dose to workers was estimated to be about 6.8 × 10(-6) Sv, which was lower than intervention exemption levels (annual dose 1.0 × 10(-3) Sv) given in International Commission on Radiological Protection (ICRP) Publication 82.
authors.affiliation: Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage, Chiba, Japan. iwaoka@nirs.go.jp
authors.forename: Kazuki
authors.initials: K
authors.lastname: Iwaoka
authors.forename: Keiko
authors.initials: K
authors.lastname: Tagami
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yonehara
mesh_terms: D001417:Background Radiation; D007221:Industry; D007501:Iron / Q000737:chemistry*; D007564:Japan; D020714:Maximum Tolerated Dose; D009532:Nickel / Q000737:chemistry*; D016273:Occupational Exposure / Q000032:analysis*; D011868:Radioisotopes / Q000032:analysis*
chemical_list: D011868:Radioisotopes; D009532:Nickel; D007501:Iron