In situ gamma-ray measurements were taken at six locations in the Modane Underground Laboratory. Count rates for gamma radiation within the energy range of 7–2734 keV varied from 15 to 108 γs⁻¹. The arithmetic mean was 79 γs⁻¹ for measurements taken without a collimator. The metamorphic rocks surrounding the Lab are characterized by low activity concentrations of uranium and thorium equal to 12 and 10 Bq kg⁻¹, respectively.

To determine background radiation levels that might influence experiments, we measured in situ gamma-ray emissions at ten locations in the Boulby Underground Laboratory. For gamma radiation in the energy range of 7–2,734 keV, the counts varied from 6.5 to 28 γ s⁻¹. For measurements inside the Lab, the arithmetic mean was 24 γ s⁻¹. The sedimentary rocks that surrounded the Lab, halite and mudstone, were characterized by very low activity concentrations of uranium (0.8–7.1 Bq kg⁻¹) and thorium (0.6–3.9 Bq kg⁻¹).

In situ gamma-ray measurements were taken at eight locations in the Gran Sasso National Laboratory (Italy). Count rates for gamma radiation within the energy range of 7–2,734 keV varied from 8 to 60 γ s⁻¹. The arithmetic mean was 49 γ s⁻¹ for measurements taken without a collimator. The average gamma flux inside the Lab was 0.25 γ cm⁻² s⁻¹. The sedimentary rocks surrounding the Lab are characterized by low activity concentrations of uranium and thorium, equal to 1.7 and 1.4 Bq kg⁻¹, respectively.

Metamict minerals contain uranium and thorium, which contribute to physical degradation or metamictization of their crystal structures over geologic time. The damage occurs primarily through progressive overlapping recoil nuclei collision cascades from α-decay of ²³⁸U, ²³²Th, ²³⁵U, and their daughter products. We measured ²²²Rn and ²²⁰Rn emanations from metamict samples of nine oxides (brannerite, davidite, fergusonites, pyrochlores, samarskites, and uraninite), two phosphates (monazites), and eight silicates (cerite, gadolinites, perrierite, rinkite, thorite, turkestanite, and vesuvianite). The total absorbed α-doses ranged from 1.4 × 10¹⁵ to 6.1 × 10¹⁸ α-decay mg⁻¹ for cerite and uraninite, respectively. The ²²²Rn emanation coefficients varied from 5 × 10⁻⁵% (uraninite) to 2.5% (turkestanite). The ²²⁰Rn emanation coefficients varied from 7 × 10⁻³% (gadolinite Ytterby) to 6.2% (gadolinite Marysin). The lowest ²²²Rn emanation coefficients occurred among metamict minerals containing the highest concentrations of ²³⁸U (i.e., uraninite, samarskites, and brannerite). Overall, the ²²²Rn and ²²⁰Rn emanation coefficients observed in this study fall significantly below previously reported values.