Measurement of natural radioactive nuclide concentrations in various metal ores used as industrial raw materials in Japan and estimation of dose received by workers handling them.
Natural resources such as ores and rocks contain natural radioactive nuclides at various concentrations. If these resources contain high concentrations of natural radioactive nuclides, workers handling them might be exposed to significant levels of radiation. Therefore, it is important to investigate the radioactive activity in these resources. In this study, concentrations of radioactive nuclides in Th, Zr, Ti, Mo, Mn, Al, W, Zn, V, and Cr ores used as industrial raw materials in Japan were investigated. The concentrations of (238)U and (232)Th were determined by inductively coupled plasma mass spectrometry (ICP-MS), while those of (226)Ra, (228)Ra, and (40)K were determined by gamma-ray spectrum. We found the concentrations of (238)U series, (232)Th series, and (40)K in Ti, Mo, Mn, Al, W, Zn, V, and Cr ores to be lower than the critical values defined by regulatory requirements as described in the International Atomic Energy Agency (IAEA) Safety Guide. The doses received by workers handling these materials were estimated by using methods for dose assessment given in a report by the European Commission. In transport, indoor storage, and outdoor storage scenarios, an effective dose due to the use of Th ore was above 4.3 x 10(-2)Sv y(-1), which was higher than that of the other ores. The maximum value of effective doses for other ores was estimated to be about 4.5 x 10(-4)Sv y(-1), which was lower than intervention exemption levels (1.0 x 10(-3)Sv y(-1)) given in International Commission of Radiological Protection (ICRP) Publication 82.
Iwaoka
Kazuki
K
Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage, Chiba 263-8555, Japan. iwaoka@nirs.go.jp
Tagami
Keiko
K
Yonehara
Hidenori
H
D019652:Extraction and Processing Industry; D006801:Humans; D007564:Japan; D008670:Metals / Q000737:chemistry*; D016273:Occupational Exposure / Q000032:analysis*; D011188:Potassium / Q000032:analysis; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000379:methods*; D011868:Radioisotopes / Q000032:analysis*; D011883:Radium / Q000032:analysis; D013910:Thorium / Q000032:analysis; D014501:Uranium / Q000032:analysis
D008670:Metals; D011868:Radioisotopes; D014501:Uranium; D013910:Thorium; D011188:Potassium; D011883:Radium