The pebble fines contribution into radiation environment of the river Yenisei floodplain in an influence zone of the Krasnoyarsk mining and chemical combine (KMCC)

The results of investigation of radioactive contamination of the river Yenisei bed pebbles in an influence zone of the KMCC (especially in its near-field part) are presented in this work. It is demonstrated, that pebbles can contain up to 30 % of the total amount of γ-emitting technogenic radionuclides (TRN) in the places with overlying soils. In addition, river bed pebbles, situated in permanently washing riverside sections of islands and banks, can contain significant amount of TRN too. These facts considerably increase an estimation of TRN reserves in the Yenisei floodplain. Without the contribution of the river bed pebbles the fraction of TRN, accumulated in the underlying and tow path pebbles in the near and far-field influence zones of the KMCC, can reach 7,9% for 137Cs, 5,8% for 152Eu, 5,6% for 154Eu and <3% for 60Co of their total amount