Characteristics of Natural Background Radiation in the Lubin Mine, Poland

There has been growing interest in using underground locations for applications in various fields, including research. In Poland, for several years, attempts have been made to build an underground laboratory. For this purpose, selecting an appropriate location requires a detailed analysis of the level of natural radioactivity. The present study presents detailed characteristics of the natural background radiation in close vicinity to shaft L-VI of the Lubin mine, at the depth of 910 m (2275 m w.e.). The in situ measurement of the photon flux in the 7-3150 keV energy range was equal to 8.08 +/- 0.90 cm(-2)s(-1), and the gamma-ray dose rate of 0.070 +/- 0.010 mu Sv/h with the highest contribution from 40K and 214B isotopes. The thermal neutron flux measured using helium counters was equal to 4.2 +/- 0.9 x 10(-6) cm(-2)s(-1). The radon concentration in the air measured with the RAD7 monitor showed low values ranging from 0 to 15.3 Bq/m(3). Laboratory measurements of rocks using alpha and gamma spectrometry techniques showed a significant variation in the concentration of Ra-226 and U-234,U-238 isotopes, and the highest concentration values were recorded for shales. The K-40, U-234,U-238 and Ra-226 isotopes make the greatest contribution to the natural radioactivity of analyzed rocks.