Radon concentration and gamma exposure in some Kosovo underground mines

Background: In this study are submitted the radon concentration measurement results of four underground mines: Stanterg, Artana, Hajvali and Badovc, which are owned by Trepça Enterprise, Kosovo. The mines have the same geological formation and from these mines are extracted ores rich with lead, zinc, silver, and gold. The radiation exposures caused by radon and radon daughters was determined and gamma dose measurements were also performed in the same time. Materials and Methods: The measurement of radon concentrations in the environment of mines is carried out by CRM 510, a portable device which continuously made measurement for four consecutive days. The gamma exposure was determined using fully portable handheld instrument GR-130 Exploranium. The detector consisted of a 65 cm3 sodium iodide NaI(Tl) and a GM tube. The system was calibrated against a 137Cs standard and checked for stability using a low-activity 9 kBq radioactive source. Results: The radon gas concentration for underground mines under study varied from minimal values 60 Bqm-3 to maximal recorded value 748 Bqm-3. The average radon concentration for mines Stanterg, Artana, Hajvali and Badovc are 301.6, 191.4, 463.2 and 527.2 Bqm-3, respectively. Conclusion: The average of total annual effective doses from radon concentration and radon decay products for miners under the study is 2.67 mSv and just from gamma ray exposure is 0.26 mSv. The average values for radon concentration and radon decay products to mines under the study are lower than action level 1000 Bq m-3 given by IAEA.