Assessment of the potential radiation hazard of the Dehmoy tailings pond (Tajikistan) for the population living around it

The paper presents results of radiation monitoring of the Dehmoy tailings pond and the nearest inhabited locality, Goziyon village. It is shown that the average gamma dose rate on the surface of Dehmoy tailings pond reaches 20 μSv/h, density of radon flux from the surface reaches 65 Bq/(m2∙s), and the outdoor radon concentration at the Dehmoy tailings pond varies from 200 to 1000 Bq/m3. It was found that the activity concentration of 238U in the tailing material reaches 980 Bq/kg and the activity concentration of 226Ra reaches 7620 Bq/kg. Potential doses for three hypothetical groups of the population living in the village of Goziyon were assessed and the following sources and ways of exposure were taken into account: external gamma radiation due to soil contamination; internal exposure due to inhalation of 222Rn and its progeny, as well as longlived radionuclides with aerosols from atmospheric air; internal exposure due to ingestion of soil particles. The hypothetical doses range from 0.4 to 17.0 mSv/year. The most significant contributors to the dose are the external gamma radiation and the internal exposure due to inhalation of 222Rn and its progeny. The  contribution of internal exposure due to the ingestion of soil particles  in the case of working in windy conditions and the lift of dust from the surface of the tailings pond can also be significant. The hypothetical annual doses to three hypothetical groups of the population can be considered as the basis for estimating the safe working time at the tailings pond during its rehabilitation. The calculated dose estimate (up to 17 mSv/year) is rather high and unacceptable compared to the dose limit for the population of 1 mSv/year above the background level. 

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