Radioactivity in Books Printed in Japan: Its Source and Relation to the Year of Issue

概要

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The radioactivities of the naturally occurring radionuclides (^<226>Ra, ^<228>Ra, ^<228>Th and ^<40>K) and a fallout nuclide (^<137>Cs) in books produced in Japan in the 20th century were measured by gamma-ray spectrometry to obtain information on radiation emitted from books. The respective concentration ranges of ^<226>Ra, ^<228>Ra, ^<228>Th ^<40>K, and ^<137>Cs were 0.2-6.4, 0.4-11. 2, 0.3-11.3, 1-112, and 0-3.6 Bq kg^<-1>. X-ray diffraction spectra of the papers used in book printing showed that pyrophyllite, talc, kaolinite, and calcium carbonate were contained as fillers. A comparison of the radioactivity contents of the pulp and filler indicated that most of ^<226>Ra, ^<228>Ra, and ^<228>Th in the books was present in the filler whereas ^<137>Cs was in the pulp. The pattern of the concentration of each nuclide vs. the year of issue of the book was investigated. Patterns for the naturally occurring radionuclides were similar and were explained by the kinds of filler used. The pattern for ^<137>Cs differed from the patterns of the naturally occurring radionuclides, having a marked peak in the mid-1960s.
日本放射線影響学会の論文
1996-06-00