チェルノブイリ原子力発電所事故起因の環境中超ウラン元素

抄録

The accident at the Chernobyl reactor site starting at 26th April 1986 caused a widespread distribution of radionuclides. In all countries radiation measurements and analyses of samples have been made to show the features to consider in a dosimetric evalution, but transuranium elements have been less investigated.
In Europe, the determination of several transuranium elements, such as neptunium (Np-239), plutonium (Pu-238, 239, 240, 241), americium (Am-241) and curium (Cm-242) was possible. The total depositions (mBq/m²) at Monaca, Rise (Denmark) and Neuherberg (Munich) were estimated to be 10, 20 and 51, respectively. These levels are only 0.01-0.05% of the previous deposition from nuclear weapons tests. The activity ratios Pu-238/Pu-239, 240 (0.4-0.5) and Pu-241/Pu-239, 240 (80-90) from Chernobyl fallout were much higher than those from nuclear weapons tests. Here, a more detailed feature of transuranium elements released into environment from the Chernobyl reactor is presented comparing with that from nuclear weapons fallout, including the measurements of transuranium elements of the Chernobyl debris in Japan.