Contribution of long lived alpha activity to the total dose of uranium mine workers

In addition to gamma radiation, radon daughter products, mine workers are exposed to longlived alpha activity (LLsup(α)) due to the inhalation of fine uranium ore dust. Concentration of LLα in the underground mine at Jaduguda was measured using personal air samplers. Twentyfour (24) mine workers of different categories used these samplers for a period of one year with cumulation period of one month in respect of each sample. Alpha activity present in the sample was determined by counting each sample for a period of 2-3 hours and the LLα concentration was calculated after taking into account the self absorption effects of the deposit on the filter paper. Based on the results it is seen that contribution of LLα to total dose varies from 3.02% to 27.25% with geometric mean of 7.76%. Compared to this, the contribution from radon daughter products varies from 42.2% to 90% with a mean of 74.16% and in the case of external gamma radiation, the corresponding figures are 6.16% to 53.15% with the mean of 14.01%. (author). 4 refs., 3 tabs