Safecast is a citizen science project, aimed to environmental monitoring. Its main activity is measuring ambient dose rate all over the world. The freely accessible data, currently (January 2020) more than 120 million observations, were used to calculate mean values of dose equivalent rate in various cities where sufficient data is available. The results mainly reflect dose rate from terrestrial radiation, whose variability is controlled by the one of geochemistry, namely the concentrations of uranium, thorium and potassium. Further influence comes from cosmic radiation and in a few cases, from anthropogenic radiation caused by nuclear fallout. Mean dose rate has been calculated for 330 cities and towns worldwide. Results are shown in tables, graphs and as maps.
- MeSH
- dávka záření * MeSH
- monitorování radiace * MeSH
- radioaktivní látky znečišťující půdu analýza MeSH
- radioizotopy draslíku analýza MeSH
- thorium analýza MeSH
- uran analýza MeSH
- velkoměsta MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- velkoměsta MeSH
The main limitation in the high-sensitive HPGe gamma-ray spectrometry has been the detector background, even for detectors placed deep underground. Environmental radionuclides such as 40K and decay products in the 238U and 232Th chains have been identified as the most important radioactive contaminants of construction parts of HPGe gamma-ray spectrometers. Monte Carlo simulations have shown that the massive inner and outer lead shields have been the main contributors to the HPGe-detector background, followed by aluminum cryostat, copper cold finger, detector holder and the lead ring with FET. The Monte Carlo simulated cosmic-ray background gamma-ray spectrum has been by about three orders of magnitude lower than the experimental spectrum measured in the Modane underground laboratory (4800 m w.e.), underlying the importance of using radiopure materials for the construction of ultra-low-level HPGe gamma-ray spectrometers.
- MeSH
- laboratoře MeSH
- metoda Monte Carlo MeSH
- monitorování radiace * MeSH
- počítačová simulace MeSH
- radioaktivní znečišťující látky analýza MeSH
- radionuklidy MeSH
- spektrometrie gama * MeSH
- thorium analýza MeSH
- uran analýza MeSH
- záření gama MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Francie MeSH
The complex radiological study of the basin of sludge from the uranium ore mining and preprocessing was done. Air kerma rates (including its spectral analysis) at the reference height of 1 m above ground over the whole area were measured and radiation fields mapped during two measuring campaigns (years 2009 and 2014). K, U and Th concentrations in sludge and concentrations in depth profiles (including radon concentration and radon exhalation rates) in selected points were determined using gamma spectrometry for in situ as well as laboratory samples measurement. Results were used for the analysis, design evaluation and verification of the efficiency of the remediation measures. Efficiency of the sludge basin covering by the inert material was modelled using MicroShield code.
- MeSH
- hodnocení programu MeSH
- hornictví * MeSH
- monitorování radiace metody MeSH
- monitorování životního prostředí MeSH
- odpadky - odstraňování metody MeSH
- radioaktivní odpad * MeSH
- radioaktivní znečišťující látky analýza MeSH
- radioizotopy draslíku analýza MeSH
- radon analýza MeSH
- regenerace a remediace životního prostředí * metody MeSH
- spektrometrie gama * MeSH
- thorium analýza MeSH
- uran * analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
This paper provides an overview of analytical methods frequently used to identify terrestrial radionuclides in samples. While radioactivity is normally measured through the ionising radiation produced during the spontaneous decay of unstable atoms, selected radionuclides or their chemical elements can be quantified with instrumental techniques based on stimulated emission or counting of atoms. The advantages and disadvantages of these analytical methods are discussed. Particular attention is paid to X-ray fluorescence analysis of materials containing uranium and thorium. It is also possible to determine the area distributions of these chemical elements in samples with the use of scanning X-ray fluorescence systems.
- MeSH
- hmotnostní spektrometrie MeSH
- mikroanalýza elektronovou sondou MeSH
- neutronová aktivační analýza MeSH
- poločas MeSH
- radiační pozadí * MeSH
- radioizotopy draslíku analýza MeSH
- radiometrie metody MeSH
- radionuklidy analýza MeSH
- spektrometrie rentgenová emisní * přístrojové vybavení MeSH
- thorium analýza MeSH
- uran analýza MeSH
- Země (planeta) * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The determination of low level activities of natural radionuclides from the uranium and thorium series by gamma-spectrometry faces the problem of proper natural background subtraction. Background fluctuation can cause differences in activity determination. Also the minimum detectable activity (MDA) of natural and artificial radionuclides can be influenced by background fluctuation. In this paper, results of the background fluctuation of shielded HPGe detectors with relative efficiency of 50-150% are presented together with the assessment of its influence on the determination of natural and artificial radionuclides.
- MeSH
- algoritmy * MeSH
- analýza selhání vybavení MeSH
- artefakty * MeSH
- dávka záření MeSH
- design vybavení MeSH
- radiační pozadí * MeSH
- reprodukovatelnost výsledků MeSH
- senzitivita a specificita MeSH
- spektrometrie gama přístrojové vybavení metody MeSH
- thorium analýza MeSH
- uran analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Concentrations of uranium, thorium and rare earth elements (REE) in 36 species of ectomycorrhizal (26 samples) and saprobic (25 samples) macrofungi from unpolluted sites with differing bedrock geochemistry were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Analytical results are supported by use of certified reference materials (BCR-670, BCR-667, NIST-1575a) and the reliability of the determination of uranium was verified by epithermal neutron activation analysis (ENAA). It appears that data recently published on these elements are erroneous, in part because of use of an inappropriate analytical method; and in part because of apparent contamination by soil particles resulting in elevated levels of thorium and REE. Macrofungi from unpolluted areas, in general, did not accumulate high levels of the investigated metals. Concentrations of uranium and thorium were generally below 30 and 125 μg kg(-1) (dry weight), respectively. Concentrations of REE in macrofungi did not exceed 360 μg kg(-1) (dry weight) and their distribution more or less followed the trend observed in post-Archean shales and loess.
Kinetics of dissolution of (238)U, (234)U and (230)Th dust deposited on filters from personal alpha dosemeters was studied by means of a 26-d in vitro dissolution test with a serum ultrafiltrate simulant. Dosemeters had been used by miners at the uranium mine 'Dolni Rozinka' at Rozna, Czech Republic. The sampling flow-rate as declared by the producer is 4 l h(-1) and the sampling period is typically 1 month. Studied filters contained 125 +/- 6 mBq (238)U in equilibrium with (234)U and (230)Th; no (232)Th series nuclides were found. Half-time of rapid dissolution of 1.4 d for (238)U and (234)U and slow dissolution half-times of 173 and 116 d were found for (238)U and (234)U, respectively. No detectable dissolution of (230)Th was found.
