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After year-long measurements with CR-39 detectors, nationwide radon survey was performed in 953 homes – 0.5 % of all permanently inhabited dwellings in Montenegro. Influence of 11 factors (area, climate, type of house, year of construction, basement, foundation slab, number of stories, building materials, window frames, heating, and smoking) and 35 their 35 categories on the radon concentrations in 732 ground-floor dwellings was analyzed using descriptive, univariate and multivariate methods. Univariate analysis dropped influence of the two factors: heating and smoking. It reveals that, on average, radon concentrations in ground-floor dwellings differ at 95 % confidence level in urban and rural areas, in family houses and apartment buildings, in houses with and without basement, and in dwellings with window frames made of wood and PVC/Al. In Cf climate zone they differ from those in Cs and Df zones. Only two pairs of construction periods differ in mean radon concentrations in dwellings: 1980-1999 with 1900-1944, and with 1964-1979. Houses with one, two or three stories have almost equal average radon levels, which are higher than in buildings with more than three stories. Mean value of radon concentrations in houses made of stone are higher than in houses made of concrete, or bricks, or wood. Multivariate analysis revealed that six of the analyzed factors: area, climate, type of house, presence of basement, number of stories, and building materials simultaneously have significant relationships (p < 0.05) with radon concentrations in dwellings on ground floor in Montenegro.

A national radon survey was performed recently in all buildings of pre-university education in Montenegro. During the school year 2016/2017, radon (222Rn) was measured with passive detectors (Radosys, RSFV type) in 2855 ground-floor rooms of 468 buildings. The average 9-month radon activity concentrations above the level of 300 Bq/m3 were found in 728 rooms, which belong to 213 buildings, while in 111 rooms, belonging to 47 buildings, they were above 1000 Bq/m3. Radon concentrations in the educational buildings, averaged over all sampled ground-floor rooms in a building, range from 16 Bq/m3 to 2810 Bq/m3, with arithmetic mean (AM) = 275 Bq/m3. They follow a log-normal distribution with geometric mean (GM) = 174 Bq/m3 and geometric standard deviation (GSD) = 2.58. There are 135 buildings with average indoor radon concentrations on the ground floor above 300 Bq/m3 and 18 buildings where they are above 1000 Bq/m3. The influence of the nine factors (climate, urban/rural area, age of building, number of stories, building materials, basement, foundation slab, window frames, and heating) on radon concentrations in the buildings was analysed by univariate (UVA) and multivariate (MVA) methods. The univariate analysis revealed the significant relationship of the four factors: age of buildings, basement, building materials, and window frames with radon concentrations on the ground floor in the buildings, while multivariate analysis added to those factors urban/rural area and number of stories, but excluded building materials as a factor influencing significantly radon concentrations.

Soil samples from Montenegro were analysed by the HPGe detector with 40 % of relative efficiency, for radioactivity due to 226Ra, 232Th and 40K. The average activity concentrations have been found to be 39.9, 43.5 and 437.6 Bq kg−1, respectively, i.e. in accordance with those in the other South European countries. In order to evaluate the health hazard, radium equivalent activity, absorbed dose rate, annual effective dose rate, external hazard index, annual gonadal dose equivalent and excess lifetime cancer risk (CR) have been calculated. The excess lifetime CR (×10−3) had a range from 0.12 to 0.79, with an arithmetic mean of 0.27, which is in accordance with the global average. Mean gonadal dose equivalent was higher than the world average, and one location was found with the radium equivalent activity >370 Bq kg−1, i.e. with the external hazard index higher than unity, which means the radiation hazard is not negligible. [ABSTRACT FROM PUBLISHER]

A coincidence method for measuring Cs, K, Ra and Th decay products activity in soil, vegetation and fish samples, was applied to the six-crystal gamma-coincidence spectrometer PRIPYAT-2M. In this way, some problems appeared in simultaneous measurement of Cs, Ra and Th by NaI(Tl) detectors and the PRIPYAT-2M spectrometer were solved. The obtained results were agreeable with the HPGe spectrometer ones. [ABSTRACT FROM AUTHOR]

232Th activities in the South Adriatic Sea-water, surface sediment, mud with detritus, seagrass ( Posidonia oceanica) samples, and the mullet (Mugilidae) species Mugil cephalus, as well as soil and sand from the Montenegrin Coast, were measured using the six-crystal spectrometer PRIPYAT-2M, which has relatively high detection efficiency and a good sensitivity, and allows a short acquisition time, and measuring samples of any shape, without preliminary preparation and calibration measurements for different sample geometries. An average 232Th activity concentration in surface soil layer is found to be 40.33 Bq kg−1, while in sand—4.7 Bq kg−1. The absorbed dose rate in air due to 232Th gamma radiation from surface soil layer ranged from 11.76 to 63.39 nGy h−1, with a mean of 24.06 nGy h−1. Corresponding average annual effective dose rate has been found to be 0.03 mSv y−1. The absorbed dose rates due to the thorium gamma radiation in air at 1 m above sand surface on the Montenegrin beaches have been found to be from 0.41 to 9.08 nGy h−1, while annual effective dose rates ranged from 0.0005 to 0.011 mSv y−1. 232Th activity concentration in seawater ranged from 0.06 to 0.22 Bq L−1, as in the mullet ( Mugil cephalus) whole individuals from 0.63 to 1.67 Bq kg−1. Annual intake of 232Th by human consumers of this fish species has been estimated to provide an effective dose of about 0.003 mSv y−1. [ABSTRACT FROM AUTHOR]

A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement with ones obtained by the HPGe spectrometer. [ABSTRACT FROM AUTHOR]

Abstract: The method for activity measurements of the 232Th daughters, developed at the six-crystal gamma-ray coincidence spectrometer PRIPYAT-2M and based on coincidence counting of the 583 and 2615keV photons from cascade transitions which follow β−-decay of 208Tl, as well as on counting the 911keV photons which follow β−-decay of 228Ac in the integral and non-coincidence mode of counting, is presented. [Copyright &y& Elsevier]

Soil samples from Mojkovac, Montenegro, were analyzed by standard gamma-spectrometry for radioactivity due to 226Ra, 232Th, 40K, and 137Cs. Average activity concentrations have been found to be 28.6, 43.1, 620.8, and 55 Bq/kg, respectively. In order to evaluate the radiation hazard, radium equivalent activity, absorbed dose rate, annual effective dose, external and internal hazard indexes, and the annual gonadal dose equivalent were determined and found to be at an average of 133.79 Bq/kg, 65.18 nGy/h, 79.93 mSv/y, 0.37, 0.45, and 0.46 mSv/y, respectively. With life expectancy taken to be 70 years, a mean lifetime outdoor gamma radiation was calculated as 5.6 mSv, yielding a lifetime cancer risk of 2.8×10-4.

Detection efficiencies of 226Ra and 232Th decay products, as well as corresponding minimum detectable activities in different modes of counting of the PRIPYAT-2M spectrometer (integral, when all pulses - coincident and non-coincident, are counted; non-coincident, when only non-coincident pulses are counted; coincident, when coincident pulses of multiplicity from 2 to 6 are counted), in energy ranges of 200 keV to 2000 keV and 300 keV to 3000 keV are presented here. It has been shown that the mode of double coincidences is the optimum one for measuring radium and thorium activity. In this mode of counting, the sensitivity of the spectrometer is the highest.

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., (© The Author(s) 2019. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

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/m 3 . Assuming a log-normal distribution of the experimental results, geometric mean GM = 58.3 Bq/m 3 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/m 3 , which is theoretically calculated. Such a transformed distribution has GM tr  = 46.7 Bq/m 3 and GSD tr  = 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/m 3 and above, which is better estimated by using GM tr and GSD tr . Based on the results of radon survey, a new national radon reference level of 300 Bq/m 3 and an "urgent action level" of 1000 Bq/m 3 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 GM tr and GSD tr . The six municipalities which have more than 10% of homes with radon concentration above 300 Bq/m 3 are recommended as radon priority areas., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

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.

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., (Copyright © 2012 Elsevier Ltd. All rights reserved.)