[en] The aim of this study was to identify the ¹³⁷Cs and ²⁴¹Am chemical forms in bottom sediments and reed of the reservoir V-17. The following samples were collected: reservoir water, bottom sediments, reed (Phragmites australis). Plant samples were washed out of the soil residues and sediments, air dried and divided into roots, stems and leaves. All samples were analyzed using gamma-spectrometry (Canberra GR 3818). The activity of ¹³⁷Cs and ²⁴¹Am in water, sediments and of reservoir-17 in 'Mayak' territory were determined. For the sequential extraction, the following procedure was used: 1) Reservoir water imitated salts mixture (water-soluble) -> 2) MgCl₂ (exchangeable) -> 3) NH₂₄Ac (carbonates) -> 4) NH₂OH^-HC (Fe-Mn oxides) -> 5) 30%H₂O₂ (organic) -> 6) HNO₃ conc. (residue). The results show the total activity of ¹³⁷Cs: (1.81 ± 0.06).10¹ Bq/ml in water, (1.50 ± 0.01).10⁵ Bq/g in bottom sediments, (3.20 ± 0.04).10³ Bq/g in roots, (2.3 ± 0.1).10³ Bq/g in leaves, (7.9 ± 0.1).10² Bq/g in stems. ²⁴¹Am: (2.1 ± 0.1).10^-2 Bq/ml in water, (5.27 ± 0.05).10³ Bq/g in bottom sediments, (2.4 ± 0.3).10¹ Bq/g in roots, (2.7 ± 0.7).10^-1 Bq/g in leaves, (5.0 ± 0.1).10^-2 Bq/g in stems. Maximum activity consider to bottom sediments and reed roots. Minimum activity was determined in water and reed leaves