ASSESSMENT OF POTENTIAL RADIATION HAZARD OF THE FORMER URANIUM FACILITIES FOR THE POPULATION OF THE ISTIKLOL CITY OF THE REPUBLIC OF TADZHIKISTAN

The article presents the results of alpha, gamma spectrometric analyzes of samples, dosimetry, radon monitoring of the estimated areas in the Istiklol city. It has been established that the specific activity of radionuclides for uranium and radium in the tailing materials are in the range: 1405 – 2140, 5935 – 9843 Bq / kg, respectively. Based on the results of the monitoring of gamma radiation and radon volume activity at Istiklol city sites, it has been established that gamma radiation ambient equivalent dose rate varies from 0.52 to 1.78 μSv / h, and radon volume activity in air ranges from 20 and 45 Bq / m3. It is shown that the radon concentration in the air above the surface of tailings is not high. However, the exhalation of radon from the soil surface of all the tailings dumps examined is above the standard (1 Bq / (m2·s). The results of measurements of radon volume activity in the air of residential buildings and facilities located on the territory of Istiklol city have shown that the value of radon volume activity is within the limits of 44 – 195 Bq / m3. A high value of radon volume activity is noted in the former dilapidated plant (1319 Bq / m3). Gamma and alpha spectrometric studies revealed that the average values   of the activity concentration of uranium and radium in the soils for tailings and the pit are for 234U – 65365 Bq / kg, for 238U – 50295 Bq / kg, and for 226Ra – 3800 Bq / kg. To estimate the doses of population irradiation via the water pathway were taken the average values   of the volumetric activity of 234U, 238U, 226Ra in the waters. Maximum values   of volumetric activity of radionuclides were observed in samples of drainage water, Bq / m3: 234U – 530000, 238U – 390000, 226Ra – 185. To calculate the contributions of various radiation factors to an additional annual dose of irradiation, the population was divided into four hypothetical groups. The time duration of stay of various hypothetical population groups in the areas of potential irradiation, radiation dose due to water use from contaminated water sources and additional factors in Istiklol were taken into account.The main contributor to the additional radiation dose received by hypothetical population groups is external irradiation during the stay on the territory of the FBR and tailing dumps, and internal irradiation due to the use of contaminated water.

analysis, radionuclide, uranium, radium, radon, volumetric activity, gamma radiation, air, soil, tailings, radiometer, dose estimation

1. Zhukovsky M.V., Yarmoshenko I.V. Radon: measurements, doses, risk assessment. Ekaterinburg, UrORAN, 1997, 232 p.

2. Method for the rapid measurement of the flux density of 222Rn from the earth’s surface using a radon radiometer of the RRA. Moscow, CSRI SE «A-RSRIPTRM», 2006, 20 p.

3. Radiation Safety Norms (NRB-06 SR 2.3.1.001-06): regist. 16.01.07. Dushanbe: Ministry of Justice of Republic of Tadzhikistan, 2007, 172 p.