Epithermal neutrons activation analysis, radiochemical and radiometric investigations of evaporitic deposits of Slanic-Prahova (Romania) salt mine

Abstract

Activation analysis / Halite / Trace element / Natural radioactivity / Underground laboratorySummary. Three highly sensitive analytical methods: epithermal neutron activation analysis (ENAA), radiometric assay and UV/Vis spectroscopy were used to investigate the elemental composition of both halite and mineral fractions (sediments) of salt collected from the Slanic-Prahova salt mine, near the location of Low Background Radiation Laboratory. For halite with all three methods and within experimental uncertainties, it was not possible to observe the presence of any natural radioactive elements. For the mineral fraction both radiometric and ENAA showed the presence of 40 K, 232 Th and 238 U in concentrations comparable to the upper continental core (UCC). The same was true for the distribution in the mineral fraction of 7 other major (Na, Al, Cl, K, Ca, Ti and Fe) and 29 trace elements (Sc, U) as determined by epithermal neutron activation analysis (ENAA), which demonstrates a continental origin of the sediments in the existing salt deposit.

A mobile detector for measurements of the atmospheric muon flux in underground sites

“…The differences between the muon fluxes in Cantacuzino and Unirea, are caused also by the fact that the overburden of the mine is not flat, due to the irregular hill's shape above the entrance. The salt ore has a relatively regular shape (see Section 2) and a homogeneous composition consisting of salt (NaCl > 98%) and different impurities (< 2%) [36]. Based on that, the m.w.e.…”

A Large Scale Characterization of the Dielectric Properties of Heterogeneous Layered Rock Salt

“…All calculus were performed considering a high purity of the rock salt in Unirea salt mine [31], expected from the geological formation process of a diapir. This assumption is supported by results reported in the literature, that show a total concentration of impurities of 22.7851 g/kg in salt samples collected from Unirea mine [44]. The high purity assumption requires that the real part of the permittivity does not vary from layer to layer [45].…”

“…The main impurities detected in the NaCl in Unirea salt mine are Al, Ca, Ti, Fe, K, Cr, V, Mn, Ni, Zn, Cu, Pb, Sr, and Ba [44]. For NaCl crystals the presence of an external electrical field generates ion mitigation which is the most important mechanism of electrical conduction.…”

“…Using the mathematical model reported in [28] and applying an inverse algorithm to the permittivities determined here, the total concentration of impurities was determined to be about 9.8 times larger than the total concentration of the sample analyzed in [44]. In calculations, the temperature was set to 13°C typical to Unirea mine and the frequency to 170 MHz.…”

Radio-Wave Propagation in Salt Domes: Implications for a UHE Cosmic Neutrino Detector

“…For homogeneous medium, the equivalent dielectric constant of salt was calculated at 187.5 MHz: = 7.4747+ 0.0003. If the concentration of all elements increases 5 times their value in [38], the imaginary part of permittivity increases almost 10 times (up to 0.002) [23]. This would correspond to an attenuation length greater than 1 km.…”