Characteristics of Natural Background Radiation in the GIG Experimental Mine 'Barbara', Poland

Underground locations can be used in various ways for scientific and economic purposes. One of the main factors influencing the safety level in the underground mine workings is natural radioactivity. The article presents research carried out on the natural radioactivity in shallow mine workings at the GIG Experimental Mine 'Barbara'. The description of the natural radiation includes radon determination in the air, in situ gamma spectrometry, neutron flux measurements, and laboratory measurements of Ra-226,Ra-228, K-40, and U-234,U-238 isotopes using gamma and alpha spectrometry techniques. In the measurement chamber at the depth 46 m (122 m w.e.) in the sandstone layer, the photon flux registered at the 7-3150 keV energy range is equal to 17.6 +/- 1.9 cm(-2)s(-1), the gamma-ray dose rate is 0.200 +/- 0.029 mu Sv/h, and the thermal neutron flux is equal to (8.6 +/- 1.1) x 10(-6) cm(-2)s(-1). After closing the measurement chamber and turning off ventilation, a significant ingrowth of Rn-222 content was observed, reaching the value of 4040 +/- 150 Bq/m(3). An increased gamma-ray flux and thermal neutron flux were observed in the investigated location.