1997 年 46 巻 2 号 p. 92-95
The radioactivities of the naturally occurring radionuclides (226Ra, 228Ra, 228Th and 40K) and a fallout nuclide (137Cs) in newspapers issued during 1990s in Japan and information business papers were determined by gamma-ray spectrometry to obtain information on radioactivity level of papers and the sources of radionuclides contained in papers. The concentrations of the naturally occurring radionuclides in the newspapers were low, whereas the 228Ra and 228Th contents of an information business paper were as high as 30 Bq kg-1. Perhaps the thorium series nuclides contained in this information business paper was present in the kaolinite filler used in the paper. 137Cs was detected in all the newspapers, while the radionuclide was not detected in the information business papers. The 137Cs concentration in the newspaper ranged from 0.1 to 0.2 Bq kg-1. Mechanical pulp was the main constituent of the newspapers, and 137Cs in the newspapers was maybe brought with the mechanical pulp which kept a part of fallout 137Cs contained in the material wood. The data obtained in this work may be useful to estimate radioactivity released from incinerators to the environment by burning waste paper.