@article{oai:repo.qst.go.jp:00055460,
 author = {Tagami, Keiko and Uchida, Shigeo and Sekine, Tsutomu and 田上 恵子 and 内田 滋夫},
 journal = {CYRIC Annual Report},
 month = {Jan},
 note = {Technetium-99 is a long-lived fission product with a half-life of 2.111 x 105 y. It is produced in appreciable amounts (6.1 %) by nuclear fission. Because of its long half-life, the migration of 99Tc in the environment is of great importance from a viewpoint of dose assessment. It is well known that pertechnetate ions (TcO4-) have a high geochemical mobility under oxidative condition and the uptake of TcO4- into plants is quite high. From a radioecological viewpoint, analysis data on global fallout 99Tc in environmental samples should give useful information to know the migration of 99Tc. At present, however, due to very low concentration and analytical difficulties for determination of the nuclide in environmental samples, knowledge on 99Tc levels is quite limited. 
In this study, we determined concentrations of 99Tc in surface soil samples collected at several sites in Japan. Radioacitivity of 137Cs in the samples was also determined as a comparative indicator, because the fission yields from 235U and 239Pu are about the same (ca. 6%) for the two nuclides, and the behavior and distribution of 137Cs in the environment is well understood. The activity ratio of 99Tc/137Cs was calculated to understand Tc mobility in the soil.},
 pages = {73--75},
 title = {Technetium-99 concentrations in Japanese rice paddy fields},
 year = {2004}
}