MAIN FINDINGS FROM RADON INDOOR SURVEY IN MONTENEGRO.

Recent residential radon survey in Montenegro revealed the national average annual radon activity concentrations: unweighted AM = 110 Bq m-3, GM = 58.3 Bq m-3, and population weighted (AM)w = 100.5 Bq m-3, (GM)w = 92.8 Bq m-3. Based on (AM)w and dose conversion factor of 9 nSv per Bq h m-3, average effective dose from exposure to indoor radon at homes is estimated to be 1.58 mSv y-1. 222Rn was measured with CR-39 detectors for two consecutive six-month periods. Radon concentrations are discussed with respect to their distribution, to the seasons, climate zones, urban and rural areas, house types, floor levels, basement and foundation slab. Average radon concentrations are calculated for each municipality and for cells of a 10 km × 10 km grid, and corresponding radon maps of Montenegro are then produced.

Radon survey in Montenegro - A base to set national radon reference and "urgent action" level.

The first nationwide indoor radon survey in Montenegro started in 2002 and year-long radon measurements with CR-39 track-etch detectors, within the national grid of 5 km × 5 km and local grids in urban areas of 0.5 km × 0.5 km, were performed in homes in half of the country's territory. The survey continued in 2014 and measurements in the rest of the country were completed at the end of 2015. The 953 valid results, obtained in the national radon survey, give an average radon activity concentration in Montenegrin homes of 110 Bq/m3. Assuming a log-normal distribution of the experimental results, geometric mean GM = 58.3 Bq/m3 and geometric standard deviation GSD = 2.91 are calculated. However, normality tests show that the experimental data are not log-normal, and that they become closest to a log-normal distribution after subtracting from them radon concentration in the outdoor air of 7 Bq/m3, which is theoretically calculated. Such a transformed distribution has GMtr = 46.7 Bq/m3 and GSDtr = 3.54. The estimations derived from positing a priory that the experimental results conform to a log-normal distribution underestimate the percentage of homes with radon concentrations at the thresholds of 300 Bq/m3 and above, which is better estimated by using GMtr and GSDtr. Based on the results of radon survey, a new national radon reference level of 300 Bq/m3 and an "urgent action level" of 1000 Bq/m3 are suggested, with estimated fractions of the national dwelling stock above these levels of 7.4% and 0.8% respectively. Fractions of homes with radon concentrations above the suggested levels are also estimated for each of the 23 municipalities in Montenegro, using appropriate GMtr and GSDtr. The six municipalities which have more than 10% of homes with radon concentration above 300 Bq/m3 are recommended as radon priority areas.

Radioactivity in Montenegro beach sands and assessment of the corresponding environmental risk.

Activity concentrations of the naturally occurring radionuclides (226)Ra, (232)Th, (40)K and anthropogenic (137)Cs in sand samples collected from 20 renowned beaches on the Coast of Montenegro have been determined using an HPGe (high purity Ge spectrometer). The average activity concentrations were found to be 7.4, 5.2, 97.3 and 0.5 Bq kg(-1), respectively. For all sand samples, the radium equivalent activity has been evaluated and found to be lower than the limit of 370 Bq kg(-1). External and internal hazard indices were less than unity. The gonadal dose equivalent was estimated to be on average 75 µSv y(-1), which is about four times lower than the global average for soil (0.3 mSv y(-1)). Calculated values of absorbed dose rates showed the range from 3.1 to 28 nGy h(-1), which is below the world median of average values (57 nGy h(-1)). The effective dose rate in the range from 3.8 to 34.4 µSv y(-1) was significantly below the recommended limit value for the public (1 mSv y(-1)). The highest dose rate was found for the Velika Plaza locality, which also showed heavy metal contents (As, B, Cd, Hg, Cr, Cu, Mn, Ni, Pb, Zn and Ba) significantly higher than in the sand from Jaz, a locality with one of the lowest dose rates.

Pu-239+240 and Cs-137 in Montenegro soil: their correlation and origin.

The (239+240)Pu activity concentrations in soil from Montenegro (six samples from three localities) have been measured for the first time. The alpha and gamma-spectrometric measurements are used to determine the (239+240)Pu/(137)Cs activity ratio, and it was found to be with an average of 0.02 and standard deviation of 0.007. This average activity ratio was applied to estimate (239+240)Pu in soil samples from the other 21 localities at which (137)Cs activity concentrations were measured. In this research obtained (either experimentally or estimated) (239+240)Pu activity concentrations (0.036-8.265 Bq kg(-1)) are comparable with those measured in some other European countries. On the basis of the results obtained in the present study and a survey of relevant literature, it is possible to conclude that Chernobyl contribution to (137)Cs contamination of Montenegro soils is dominant, whilst Pu contamination comes from the global fallout of nuclear weapon tests.