Radon release at a rehabilitated uranium mine site and dose assessment (case of the former Beshtaugorskiy mine, North Caucasus).

The uranium mines both developed and abandoned appear to be one of the most significant sources of radon exhalation in the world. Therefore, the study of radon exposure of the population in the areas around rehabilitated uranium mines is very important. This article presents the results of the radon release studies at the rehabilitated Beshtaugorsky uranium mine site, which is now used by local people for hiking and picnicking.

Phase Relations in the O-CrO-BO ( = Gd-Lu) Ternary Oxide Systems.

In this work, isothermal sections of the O-CrO-BO ( = Gd-Lu) ternary oxide systems at 900, 1000, and 1100 °C were constructed by determining the phase relations by using a powder X-ray diffraction technique. As a result, these systems were divided into subsidiary subsystems. Two types of double borates, Cr(BO) ( = Gd-Er) and Cr(BO) ( = Ho-Lu), were observed in the investigated systems.

Manganese Luminescent Centers of Different Valence in Yttrium Aluminum Borate Crystals.

We present an extensive study of the luminescence characteristics of Mn impurity ions in a YAl3(BO3)4:Mn crystal, in combination with X-ray fluorescence analysis and determination of the valence state of Mn by XANES (X-ray absorption near-edge structure) spectroscopy. The valences of manganese Mn2+(d5) and Mn3+(d4) were determined by the XANES and high-resolution optical spectroscopy methods shown to be complementary. We observe the R1 and R2 luminescence and absorption lines characteristic of the 2E ↔ 4A2 transitions in d3 ions (such as Mn4+ and Cr3+) and show that they arise due to uncontrolled admixture of Cr3+ ions.