The unique feature of nuclear accidents with neutron exposure is the induced radioactivity in body tissues. For dosimetry purposes, the most important stable isotopes occurring in human body, which can be activated by neutrons, are 23 Na and 32 S. The respective activation reactions are as follows:23Na(n,γ)24Na and32S(n,p)32P. While sodium occurs in human blood, sulfur is present in human hair. In order to verify the practical feasibility of this dosimetry technique in conditions of our laboratory, samples of human blood and hair were irradiated in a channel of a training reactor VR-1.24Na activity was measured by gamma-ray spectrometry.32P activity in hair was measured by means of a proportional counter. Based on neutron-spectrum calculation, relationships between neutron dose and induced activity were derived for both blood and hair.
- MeSH
- dávka záření MeSH
- krev účinky záření MeSH
- lidé MeSH
- neutrony * MeSH
- radioaktivita MeSH
- radioizotopy fosforu analýza MeSH
- radioizotopy sodíku MeSH
- radiometrie metody MeSH
- síra analýza MeSH
- sodík analýza MeSH
- únik radioaktivních látek MeSH
- vlasy, chlupy účinky záření MeSH
- záření gama MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Česká republika MeSH
An in situ diffusion experiment was performed at the Grimsel Test Site (Switzerland). Several tracers ((3)H as HTO, (22)Na(+), (134)Cs(+), (131)I(-) with stable I(-) as carrier) were continuously circulated through a packed-off borehole and the decrease in tracer concentrations in the liquid phase was monitored for a period of about 2years. Subsequently, the borehole section was overcored and the tracer profiles in the rock analyzed ((3)H, (22)Na(+), (134)Cs(+)). (3)H and (22)Na(+) showed a similar decrease in activity in the circulation system (slightly larger drop for (3)H). The drop in activity for (134)Cs(+) was much more pronounced. Transport distances in the rock were about 20cm for (3)H, 10cm for (22)Na(+), and 1cm for (134)Cs(+). The dataset (except for (131)I(-) because of complete decay at the end of the experiment) was analyzed with different diffusion-sorption models by different teams (IDAEA-CSIC, UJV-Rez, JAEA) using different codes, with the goal of obtaining effective diffusion coefficients (De) and porosity (ϕ) or rock capacity (α) values. From the activity measurements in the rock, it was observed that it was not possible to recover the full tracer activity in the rock (no activity balance when adding the activities in the rock and in the fluid circulation system). A Borehole Disturbed Zone (BDZ) had to be taken into account to fit the experimental observations. The extension of the BDZ (1-2mm) is about the same magnitude than the mean grain size of the quartz and feldspar grains. IDAEA-CSIC and UJV-Rez tried directly to match the results of the in situ experiment, without forcing any laboratory-based parameter values into the models. JAEA conducted a predictive modeling based on laboratory diffusion data and their scaling to in situ conditions. The results from the different codes have been compared, also with results from small-scale laboratory experiments. Outstanding issues to be resolved are the need for a very large capacity factor in the BDZ for (3)H and the difference between apparent diffusion coefficients (Da) from the in situ experiment and out-leaching laboratory tests.
- MeSH
- chemické znečištění vody analýza MeSH
- difuze MeSH
- oxid křemičitý * MeSH
- poréznost MeSH
- radioaktivní látky znečišťující vodu analýza MeSH
- radioizotopy cesia analýza MeSH
- radioizotopy jodu analýza MeSH
- radioizotopy sodíku analýza MeSH
- silikáty hliníku MeSH
- sloučeniny draslíku MeSH
- teoretické modely * MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
- Geografické názvy
- Švýcarsko MeSH
With the aid of in vivo whole-body counting of the rats (administered simultaneously with the radionuclides (82)Br and (24)Na) by high-resolution gamma-ray spectrometry, we extended the applicability of our experimentally proved hypothesis that the biological half-life of bromide depends on the magnitude of sodium intake rather than on the intake of chloride, as was generally assumed. Variations in the biological half-life of bromide, as a substitute for sodium, were investigated in animals situated in very different physiological states, as regards their metabolic activity.
- MeSH
- draslík farmakologie MeSH
- krysa rodu rattus MeSH
- maternofetální výměna látek MeSH
- ouabain farmakologie MeSH
- placenta krevní zásobení metabolismus účinky léků MeSH
- radioizotopy chromu diagnostické užití MeSH
- radioizotopy sodíku diagnostické užití MeSH
- sodík metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- MeSH
- blokáda Tawarova raménka diagnostické zobrazování MeSH
- diagnostické techniky kardiovaskulární trendy MeSH
- infarkt myokardu diagnostické zobrazování MeSH
- ischemická choroba srdeční diagnostické zobrazování prevence a kontrola MeSH
- lidé MeSH
- radioisotopová angiografie * metody trendy MeSH
- radioisotopová scintigrafie * metody trendy MeSH
- radioizotopy sodíku MeSH
- radionuklidy * klasifikace MeSH
- zátěžový test metody normy trendy MeSH
- zobrazování myokardiální perfuze metody trendy MeSH
- Check Tag
- lidé MeSH
