The Techa River in the Urals was contaminated with high-level radioactive waste from the MAJAK nuclear installation around 1950. The total discharge to the river amounted to 100 PBq with 90Sr and 137Cs contributing approximately 10 PBq each. This study has shown that the river presently contains approximately 0.3 TBq 90Sr, > 6 TBq 137Cs, and approximately 8 GBq 239,240Pu. The estimates were made for the part of the river starting 50 km from the point of discharge and ending 240 km downstream at the confluence with the Iset River. Radioactivity was measured only in the upper 0.10-m sediments layer. The external dose rates from the contamination range from 0.1-30 microGy h-1. The activity concentrations decrease exponentially or by power functions with distance.

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Introduction. The article presents data on tritium concentrations in various types of aquatic environments (rainfall, snowfall, water from the Irtyash, B. Nanoga, Kyzyltash lakes, and the source of the Techa river, tap water, ice from the refrigerator, and urine) within the city of Ozersk and on the territory immediately adjacent to it in the impact zone of Mayak Production Center in the Southern Urals. Material and methods. For the quantitative determination of tritium in various aqueous media, sampling was carried out from 2002 to 2016. Samples were analyzed by the scintillation method using a single-stage electrolytic enrichment procedure. Results. Almost all aquatic environments in Ozersk in terms of their tritium content exceed the technogenic background established for the Ural region. On average, this excess is by 14, 11, 9, 19, 4, 6, 19 times for rainfall, snowfall, drinking water of residential premises, ice, the water of the Irtyash and B. Nanoga lakes, water from the source of the river Techa accordingly. Elevated concentrations of tritium in the urine of Ozersk people and the adjacent territory were noted in comparison with literature data for other regions of the world. Conclusion. The obtained research results revealed the levels of pollution of the aquatic environment of Ozersk with tritium relative to the level of technogenic background. These works indicate the need to develop a method for cleaning tritium emissions and discharges by nuclear enterprises to reduce the risk to the population.

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