Variation of ²¹°Po daily urinary excretion for male subjects at environmental level.

(210)Po was determined in 24-h urine of seven healthy males from Prague, Czech Republic, for ten consecutive days. The results show that for each volunteer, the urinary excretion of (210)Po changed only little from day to day in the studied time period. For two volunteers, the difference in the daily excreted (210)Po activity for two consecutive days was not significant, given the 95% confidence interval (two sigma) of the activity measurements. The same is valid for the excretion data of the other volunteers, except for some days where the differences were slightly higher. The range of daily urinary excretion of (210)Po of each volunteer in the studied time period was quite narrow. Among the volunteers, the maximum daily urinary excretion value of (210)Po was at most about a factor of 2.5 higher than the lowest excretion value. An attempt to explain the observed small inter-individual variability of (210)Po excretion in daily urine is made.

Long-term ¹³7Cs activity monitoring of mushrooms in forest ecosystems of the Czech Republic.

This paper reports on results of activity mass concentration analyses performed in various forest mushrooms in the Czech Republic within 1986 and 2011. The estimated effective half-life of (137)Cs and its environmental half-life (i.e. the effective half-life minus the effect of physical decay) were found to be 5.6 ± 0.6 and 6.9 ± 0.7 y, respectively. Non-homogeneity in (137)Cs surface contamination over the country's territory and fungus species-based (137)Cs accumulation capacity then account for a span of up to 4 orders of magnitude in activity mass concentrations measured each year after the Chernobyl accident. The highest geometric activity mass concentration (Bq kg(-1) of dry weight) means of (137)Cs (obtained from samples between years 2004 and 2011) were measured in Suillaceae (1050 Bq kg(-1)) and Boletus badius (930 Bq kg(-1)), the lowest in Agaricus (1 Bq kg(-1)). The geometric mean of all mushrooms amounted to 230 Bq kg(-1), being 440 Bq kg(-1) in Boletales, 150 Bq kg(-1) in Russulales and 21 Bq kg(-1) in Agaricales. Geometric standard deviation levels were generally high. The highest Cs accumulation capacity was observed in Boletales (namely in Suillaceae), while the lowest in Agaricales, being over 3 orders of magnitude lower than in Suillaceae.

Field tests using radioactive matter 2.

Results of field tests with explosive dispersal of a radioactive substance (RaS) are presented. The paper deals with tests exploiting artificial obstacles as a continuation and expansion of the tests used in this study performed in free area described previously. The essential goal of the tests was to estimate the distribution of the released RaS in the case of intentional abuse of radioactive sources and to get a set of data applicable to testing physical or mathematical models of propagation. Effects of different geometrical and meteorological conditions on the distribution of dispersed RaS were studied via the assessment of dose rate, surface and volume activities, aerosol mass and activity aerodynamic diameters. The principal results can be summarised as follows: the prevalent proportion of the activity of the radionuclide dispersed by an explosion (born by the blast wave and by air convection) is transferred to the detection system/collecting pads essentially within the first minute. Enhanced aerosol mass concentrations were also detected within the same period. The RaS carried by the blast wave passed through the polygon (50 m) within <1 s. An expected crucial impact of meteorological conditions at the moment of the explosion and shortly after was proved by the tests.

Field tests using radioactive matter.

During recent years, the assessment of possible radiological consequences of a terrorist attack associated with a release of radioactive substances (RaS) has been in the focus of interest of emergency preparedness and radiation protection specialists, as well as experts dealing with the dispersion of harmful substances in the atmosphere. Suitable tools for these analyses are applications of mathematical and physical models and simulation of this attack under 'realistic' conditions. The work presented here summarises the results of four tests, in which a RaS (a Tc-99 m solution) was dispersed over a free area with the use of an industrial explosive. Detection methods and techniques employed in these tests are described and values characterising the RaS dispersion--dose rates, surface activities in horizontal and vertical directions, volume activities, their space and time distributions and mass concentrations of aerosols produced after the explosion are presented and compared. These data will be applied to a comparison of outcomes of models used for the assessment of radiation accidents as well as in future field tests carried out under conditions of more complex geometry (indoor environment, terrain obstacles, etc.).

Low level air radioactivity measurements in Prague, Czech Republic.

Activity concentrations of radionuclides in the atmosphere have been monitored for over 21 years in the Czech Republic, at present at 10 sampling sites. Results of long-time observation of the radionuclides (137)Cs, (7)Be, (210)Pb, (22)Na, (40)K, (238)Pu, (239,240)Pu, (90)Sr, (85)Kr and (14)C and statistical analysis of the data from the monitoring site in Prague are given in the paper. In 2007 mean activity concentrations of monitored radionuclides at Prague monitoring site in Bq/m(3) were: (85)Kr, 1.6 x 10(+0); (14)C, 5.3 x 10(-2); (137)Cs, 6.8 x 10(-7); (7)Be, 4.3 x 10(-3); (210)Pb, 5.3 x 10(-4); (40)K, 1.8 x 10(-5); (22)Na, 3.5 x 10(-7); (90)Sr, 5-7 x 10(-8); (238)Pu, 1-2 x 10(-10) and (239,240)Pu, 1.7 x 10(-9).

Long term monitoring of 137Cs in foodstuffs in the Czech Republic.

This work presents the results of (137)Cs content long-term monitoring (1986-2007) in selected groups of foodstuffs. The data in the period of 1992-2007 were roughly log-normally distributed (beef, pork, milk). The more detailed statistical evaluation in this period of time was performed. Maximum likelihood method was used for estimation of the mean values. Several methods for decreasing the detection limits of (137)Cs (detector efficiency, sample preparation, counting containers) are listed and compared.