title: Activity concentration of natural radioactive nuclides in nonmetallic industrial raw materials in Japan.
abstract: Natural materials such as rock, ore, and clay, containing natural radioactive nuclides are widely used as industrial raw materials in Japan. If these are high concentrations, the workers who handle the material can be unknowingly exposed to radiation at a high level. In this study, about 80 nonmetallic natural materials frequently used as industrial raw materials in Japan were comprehensively collected from several industrial companies, and the activity concentrations of (238)U series, (232)Th series and (40)K in the materials was determined by ICP-MS (inductively-coupled plasma mass spectrometer) and gamma ray spectrum analyses. Effective doses to workers handling them were estimated by using methods for dose estimation given in the RP 122. We found the activity concentrations to be lower than the critical values defined by regulatory requirements as described in the IAEA Safety Guide. The maximum estimated effective dose to workers handling these materials was 0.16 mSv y(-1), which was lower than the reference level (1-20 mSv y(-1)) for existing situation given in the ICRP Publ.103.
authors.affiliation: Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan; Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Honcho, Hirosaki, Aomori 036-8564, Japan. Electronic address: iwaoka@nirs.go.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Iwaoka
authors.affiliation: Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tabe
authors.affiliation: Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Yonehara
mesh_terms: D006801:Humans; D007221:Industry; D007564:Japan; D013058:Mass Spectrometry; D016273:Occupational Exposure; D011197:Potassium Radioisotopes / Q000032:analysis; D011834:Radiation Monitoring; D011851:Radioactivity; D011868:Radioisotopes / Q000032:analysis*; D013051:Spectrometry, Gamma; D013910:Thorium / Q000032:analysis*; D014501:Uranium / Q000032:analysis*
chemical_list: D011197:Potassium Radioisotopes; D011868:Radioisotopes; D014501:Uranium; D013910:Thorium
keywords: Activity concentration; Dose estimation; NORM; Nonmetallic material