Long-lived radionuclides in the air of the Dolni Rozinka uranium mine

Rozna I is the last open uranium mine in Europe, employing about 400 A-category (underground) workers who are exposed to three types of dose commitment: external gamma radiation, inhalation of short-lived radon decay products, and inhalation of long-lived alpha radionuclides of the uranium family. The paper discusses the last-mentioned factor, for which the derived limit for irradiation from the inhalation of a mixture of long-lived alpha emitters of the uranium family is 1850 Bq per calendar year as set by the Czech State Office for Nuclear Safety Decree No. 307/2002 (as amended by Decree No. 499/2005). Four major factors determine the extent of inhalation of long-lived radionuclides in mine air: concentration of uranium and their daughters in the ore, type of mining work being performed, intensity of ventilation, and intensity of spraying. The long-lived component of contamination of the mine atmosphere can be divided into 2 parts: the before-radon radionuclides (234U, 230Th, 226Ra), released during the rock separation work, and the after-radon radionuclides (210Po), which are due to radon decay