Analysis of specific radionuclides activity variations in soil within geotectonic units of Republic of North Macedonia

To establish baseline values for concentrations of terrestrial radionuclides for the Republic of North Macedonia, a survey covering the entire territory was performed. The 213 soil samples were collected from regions around the major settlements and cities, approximately evenly distributed over the geotectonic units which constitute the country's geological foundation. The specific activities of radionuclides were measured by gamma spectrometry. The following geometric mean values and geometric standard deviations were obtained: 550 Bqkg(-1) (1.47) for K-40, (37) Bqkg(-1) (1.33) for Ra-226, 38 Bqkg(-1) for U-238, and 38 Bqkg(-1) (1.53) for Th-232 in dry soil. The relation between specific activities of natural radionuclides and geology was investigated. Correlation between radionuclides, which may serve as additional geochemical indicators, and geology could not be found convincingly,. Mutual correlations between Ra-226, U-238, and Th-232 activities were found to be high (Spearman rho about 0.8), whereas the ones between these and K-40 are a bit lower, somewhat above rho = 0.6

Factors affecting indoor radon variations: A case study in schools of eastern macedonia

The subject of this study is the radon concentrations variations, measured with a nuclear track detectors in a total of 58 premises in all 29 primary schools of 4 municipalities in the Eastern part of the Republic of Macedonia. Despite a relatively small territory, the variability of radon concentrations proved to be significant. The geometric means (geometric standard deviations) of radon concentrations in the examined municipalities were in the range from GM = 71 Bq/m 3 (GSD = 2.08) to GM = 162 Bq/m 3 (GSD = 2.69), while for the entire region it was: GM = 96 Bq/m 3 (GSD = 2.47). The influence of the geographical and geological features of the school site as well as the building characteristics on the radon variations were investigated. The analysis showed that type of municipality, building materials, basement and geology have significant effects and respectively describe 6%, 16%, 22%, 39% of the radon total variability

High annual radon concentration in dwellings and natural radioactivity content in nearby soil in some rural areas of Kosovo and Metohija

Some previous studies on radon concentration in dwellings of some areas of Kosovo and Metohija have revealed a high average radon concentration, even though the detectors were exposed for three months only. In order to better design a larger study in this region, the annual measurements in 25 houses were carried out as a pilot study. For each house, CR-39-based passive devices were exposed in two rooms for the two consecutive six-month periods to account for seasonal variations of radon concentration. Furthermore, in order to correlate the indoor radon with radium in nearby soil and to improve the knowledge of the natural radioactivity in the region, soil samples near each house were collected and 226Ra, 232Th, 40K activity concentration were measured. The indoor radon concentration resulted quite high from the average (163 Bq/m3) and generally it did not differ considerably between the two rooms and the two six-month periods. The natural radionuclides in soil resulted to be distributed quite uniformly. Moreover, the correlation between the226Ra content in soil and radon concentration in dwellings resulted to be low (R2=0.26). The annual effective dose from radon and its short-lived progeny (5.5 mSv, in average) was calculated by using the last ICRP dose conversion factors. In comparison, the contribution to the annual effective dose of outdoor gamma exposure from natural radionuclides in soil is nearly negligible (66 mSv). In conclusion, the observed high radon levels are only partially correlated with radium in soil; moreover, a good estimate of the annual average of radon concentration can be obtained from a six-month measurement with a proper choice of exposure period, which could be useful when designing large surveys

Design, Analysis, and Fabrication of a Snake-Inspired Robot with a Rectilinear Gait

Snake-inspired robots display promise in areas such as search, rescue and reconnaissance due to their ability to locomote through tight spaces. However, several specific issues regarding the design and analysis must be addressed in order to better design them. This thesis develops kinematic and dynamic models for a class of snake-inspired gait known as a rectilinear gait, where mechanism topology changes over the course of the gait. A model using an Eulerian framework and Coulomb friction yields torque expressions for the joints of the robot. B-spline curves are then used to generate a parametric optimization formulation for joint trajectory generation. Exact gradient computation of the torque functions is presented. A parametric model is used to describe the performance effects of changing system parameters such as mass, length, and motor speed. Finally, a snake-inspired robot is designed and fabricated in order to demonstrate both the vertical rectilinear gait and a modular, molded design aimed at reducing the cost of fabrication

Factors affecting indoor radon variations: A case study in schools of eastern macedonia

The subject of this study is the radon concentrations variations, measured with a nuclear track detectors in a total of 58 premises in all 29 primary schools of 4 municipalities in the Eastern part of the Republic of Macedonia. Despite a relatively small territory, the variability of radon concentrations proved to be significant. The geometric means (geometric standard deviations) of radon concentrations in the examined municipalities were in the range from GM = 71 Bq/m 3 (GSD = 2.08) to GM = 162 Bq/m 3 (GSD = 2.69), while for the entire region it was: GM = 96 Bq/m 3 (GSD = 2.47). The influence of the geographical and geological features of the school site as well as the building characteristics on the radon variations were investigated. The analysis showed that type of municipality, building materials, basement and geology have significant effects and respectively describe 6%, 16%, 22%, 39% of the radon total variability

Prediction of Long-Term Indoor Radon Concentration Based on Short-Term Measurements

We present a method for the estimation of annual radon concentration based on short-term (three months) measurements. The study involves results from two independent sets of indoor radon concentration measurements performed in 16 cities of the Republic of Macedonia. The first data set contains winter and annual radon concentration obtained during the National survey in 2010 and the second, contains only the radon concentration measured during the winter of 2013. Both data sets pertain to radon concentration from the same cities and have been measured applying the same methodology in ground floor dwellings. The results appeared to be consistent and the dispersion of radon concentration was low. Linear regression analysis of the radon concentration measured in winter of 2010 and of the 2010 annual radon concentration revealed a high coefficient of determination R-2 = 0.92, with a relative uncertainty of 3%. Furthermore, this model was used to estimate the annual radon concentration solely from winter-term measurements performed in 2013. The geometrical mean of the estimated annual radon concentration of the 2013: radon concentration (A-2013) =98 Bqm(-3) was almost equal to the geometrical mean of the annual radon concentration from the 2010, radon concentration (A-2010) = 99 Bqm(-3). Analysis of the influence of building characteristics, such as presence/absence of a basement in the building, or the dominant building material on the estimated annual radon concentration is also reported. Our results show that a low number of relatively short-term radon measurements may produce a reasonable insight into a gross average obtained in a larger survey

Radon levels and resulting effective doses of residents in Gornja Stubla at Kosovo applying dosimetric lung models based on ICRP 65 and ICRP 66 methodology

The town Gornja Stubla, situated in the South-West part of Kosovo, is a community with high indoor radon level due to its geochemical background. Radon activity concentration in indoor air has been measured by exposing the 960 track-etch detectors for one year, in 172 rooms of 65 dwellings. Annual averages of concentration ranged from 35 Bq/m3 to 6010 Bq/m3. In a first attempt, the effective doses of residents have been calculated applying the ICRP 65 methodology, based on the average radon concentration for the dwelling and for concentrations in the rooms of a dwelling in which they spend fractions of the entire time spent indoors. Both seasonal and annual doses have been calculated. The annual values were in the range of 0.6−107 mSv/a with an average value of 8.6 mSv/a. As nest step we considered that effective dose, being influenced by a number of different parameters and divided into subject and aerosols related parameters, is connected with two crucial parameters, namely, the Dose Conversion Factor (DCF) [mSv/WLM] for a particular person (accounting for real gender, age and physical activity level) and indoor radon concentration and its short lived progeny at field area. Therefore, software based on ICRP Publication 66 was developed for determination of effective dose per unit inhaled activity of radon progeny, DCF. According to the results of indoor radon measurements in the area of Gornja Stubla, the effective dose for its population was estimated by using the dosimetric lung model. The results, obtained according to ICRP 66, were compared with results calculated according to ICRP Publication 65

Prediction of Indoor Radon Risk from Radium Concentration in Soil: Republic of Macedonia Case Study

Geo-referenced datasets of indoor radon concentrations and radium concentrations in soil are available for the Republic of Macedonia. However, the indoor Rn-222 data are spatially strongly clustered as the measurements were essentially confined to major towns and cities. Hence, the estimation of the geographical distribution of Rn-222 concentration based only on the Rn-222 data is difficult to be made. On the other hand, geochemical measurements Ra-226 are quite well distributed over the country. Since Ra-226 is the source of Rn-222, one may think of using Ra-226 as a predictor for Rn-222. In this paper we present a method for modelling the stochastic dependency of indoor Rn-222 of soil Ra-226. The method is new in the area on Rn-222 assessment and still needs to be validated by more case studies. It must be born in mind that the indoor Rn-222 depends, in some cases more strongly, on controlling factors other than the Ra-226 in soil, so that its estimation from Ra-226 alone is inevitably imperfect. The results must therefore be understood as estimates in absence of other information, and as a motivation to carry out measurements in regions where the model predicts higher Rn-222 levels, but for which no measurements are available so far.1st East European Radon Symposium (FERAS), Sep 02-05, 2012, Cluj Napoca, Romani

Effective dose for real population exposed to indoor radon in former uranium mine area Kalna (Eastern Serbia)

This paper deals with calculated effective doses that members of real population received from radon gas and its short lived progeny during air inhalation in their dwellings at field site Kalna in Eastern Serbia. There are two crucial parameters in effective dose calculation: Dose Conversion Factor (DCF) for particular subjects (including real gender, age and physical activity level) and indoor concentration of radon and its short lived progeny in field area. According to the results of indoor radon measurements in the area of former uranium mine, Kalna, the effective dose for this real population was estimated by using the dosimetric lung model, developed by authors according ICRP Publication 66 [1]. Authentic software was developed for determination of effective dose per unit inhaled activity of radon progeny, DCF expressed in unit [mSv/WLM]. The results, obtained according to ICRP66 dosimeter lung model [1], were compared with results calculated according to ICRP Publication 65 [2]. The dosimetric results were, also, compared and discussed with epidemiological approach data, according to UNSCEAR [3]

Seasonal indoor radon concentration in FYR of Macedonia

This paper presents the results of the seasonal indoor radon concentration measurements in dwellings in all regions of the Former Yugoslav Republic (FYR) of Macedonia. The measurements were made in 437 dwellings using CR-39 track detectors over four successive three-month periods (winter, spring, summer and autumn) throughout 2009. The results of analysis of variance showed statistically significant differences between indoor radon concentrations in different seasons. The geometric mean values and geometric standard deviations of indoor radon concentrations in winter, spring, summer and autumn were obtained to be: 115 Bq m(-3) (2.02), 72 Bq m(-3) (1.97), 46 Bq m(-3) (1.95), 92 Bq m(-3) (2.02), respectively. The geometric mean values of spring, summer and autumn to winter ratios were found to be: 0.63 (1.50), 0.40 (1.81), and 0.80 (1.58), respectively. The results of the analysis of the variance showed statistically significant differences among the indoor radon measurements for the regions in different seasons. The influence of the factors linked to building characteristics in relation to radon measurements in different seasons was examined. The factors which enable a differentiation into subgroups (significance level p LT 0.05) are the floor level, basement and building materials. (C) 2011 Elsevier Ltd. All rights reserved