Characterization of underground laboratories in terms of their natural radioactivity is necessary to determine the conditions that prevail there and plan using these sites for scientific research and other activities. The article compares natural background radiation in three underground laboratories located in the Baltic Sea region. The comparison includes measurements made in underground laboratories (in-situ) and detailed laboratory analyses of water and rock samples taken from these locations. Measurements were made by gamma, alpha spectroscopy, and LSC technique.

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