The possibility of the phosphogypsum use in the production of brick: Radiological and structural characterization.

In this paper, phosphogypsum (PG) with the content of 226Ra of about 500 Bq kg-1 was used as a clay additive in mass ratios of (0-40) % and its influence on the radiological and mineralogical characteristics of the obtained brick samples was monitored. After sintering the samples at 1000 â„ƒ, the formation of the mineral phase gehlenite was observed, and its share increased with the share of PG in the samples. The Monte Carlo method was used to determine the gamma dose rates, and consequently annual effective dose, for a standard room, with dimensions 4 × 5 × 2.8 m, whose walls were built of brick with PG. The obtained values were in the range (0.22-0.35) mSv y-1. In addition, the active device RAD7 was used to determine the radon surface exhalation rates from the samples, which were found to be in the range (63-150) mBq m-2 h-1. The estimated indoor radon concentrations were found to be drastically lower than 100 Bq m-3, leading to low radon inhalation doses. However, estimated annual effective doses from external gamma exposure were found not to be insignificant.

Deposition of 137Cs and precipitation distribution in Vojvodina, Northern Serbia after the Chernobyl accident.

There is a dilemma whether the Chernobyl accident is the main source of this anthropogenic radionuclide in the region of Vojvodina, Northern Province of Serbia. The difference compared to the other dominant source of radiocaesium in the environment, the nuclear weapon tests, is lying in the local character of contamination due to accidents, which implies it's highly dependent on meteorological parameters, such as precipitation and wind in the area at that time. According to published data, the average value of surface contamination by radiocaesium on the territory of the former Yugoslavia after the Chernobyl accident was several times higher than the estimated contamination by nuclear testing (1945-1963). The main aim of this research is to explore possible correlations of the spatial distribution of precipitation from April 1986 to December 1987 with the deposition of radiocaesium in the surface soil to justify this claim in the absence of data on caesium deposition before the Chernobyl accident for the Vojvodina region. The database of 137Cs content in Vojvodina soil and precipitation for this region during the timeframe of interest were used. From a total of 245 precipitation stations in Vojvodina, 164 to 244 precipitation stations were selected for analysis in conditionals from different time scale aspects and data validation. The best correlation between amounts of total precipitation and 137Cs content in surface soil obtained for two rainy periods 2nd-5th and 7th-21st May 1986. Further cluster analysis separated four different regions according to 137Cs deposition and precipitation for the mentioned rainy period which could be applied in the field of soil erosion assessment on the local and regional level.

RADIOLOGICAL IMPACTS ASSESSMENT FOR WORKERS IN CERAMIC INDUSTRY IN SERBIA.

Studies have been carried out to determine the natural radioactivity in some materials used in ceramic industry (zircon, zirkosil, Zircobit MO/S, zircon silicate, zirklonil frit, hematite, bentonite, wollastonite, raw kaolin, kaolinized granite, sileks ball, feldspar, pigment, white base serigraphic, engobe) and their associated radiation hazard. The external hazard index, Hex, values, radium equivalent activity, Raeq, total absorbed dose rates, D and annual effective dose, De were derived for all measured materials and compared with the recommended values to assess the external radiation hazards to workers who worked in ceramic industries in Serbia.

Concentrations of 226Ra, 232Th and 40K in industrial kaolinized granite.

Activity concentrations of 226Ra, 232Th and 40K in 120 kaolinized granite samples imported in Serbia from the Motajica mine, Bosnia and Herzegovina, were measured. The 226Ra concentration ranged from 61 to 319 Bq kg-1, the 232Th from 44 to 272 Bq kg-1, and the 40K from 590 to 1470 Bq kg-1. The frequency distribution of 40K concentrations was near-Gaussian, where those of 226Ra and 232Th were right-skewed. In 6 samples, the gamma index, I, was higher than 2, which exceeds the exemption dose criterion (0.3 mSv y-1). The absorbed dose rate and annual effective doses for workers in the ceramic industries in Serbia who worked with kaolinized granite were below levels of concern.

Improvement of measuring methods and instrumentation concerning (222)Rn determination in drinking waters - RAD7 and LSC technique comparison.

A procedure for the determination of (222)Rn in environmental water samples using liquid scintillation counting (LSC) was applied and optimized. A minimum detectable activity of 0.029Bql(-1) in a 20ml glass vial (10ml water sample mixed with 10ml of liquid scintillation cocktail) has been achieved during 300min of measurement time. The procedure was compared with RAD7 radon detector measurements. (226)Ra content in the water was determined by gamma-ray spectroscopy. Applications to drinking waters collected from public drinking fountains in the Vojvodina (Serbia) are presented with annual effective dose for ingestion and inhalation for adults calculated.

Radon in thermal waters in south-east part of Serbia.

There are several occurrences of thermal waters in the south-eastern part of Serbia, which are originating from igneous and metamorphic rocks. These waters are mainly used in balneology, but some of them are used for drinking purposes and in water supply to heat buildings, for greenhouses and to irrigate land. In this region, there is the well-known Niska banja spa, which has elevated levels of radon. Water samples were examined from other spas in the south-eastern part of Serbia in order to determine radon activity concentration. A detailed discussion of a possible correlation between determined radon activity concentration and the geology of this area is also given.

Radioactivity in the indoor building environment in Serbia.

Measurement of activity concentrations of radionuclides in building materials and radon in indoor space is important in the assessment of population exposures, as most individuals spend 80 % of their time indoors. This paper presents the results of activity concentration measurements of: radon emanated from the soil, radionuclides (226)Ra, (232)Th and (40)K in the soil, indoor radon in the city of Novi Sad (the capital city of Vojvodina) using charcoal canisters and indoor radon in the Vojvodina region using alpha-track detectors and the radioactivity of some building materials. Influences of floor level, space under the rooms, boarding, and the heating system on indoor radon accumulation in the Vojvodina province, situated in the northern part of Serbia, are also presented in this paper. The total effective dose and the activity concentration index are calculated applying the dose criteria recommended by the European Union for building materials.

Airborne radioiodine in northern Serbia from Fukushima.

The results obtained with the monitoring system set up to assess the impact of the Fukushima accident on the environment of Vojvodina (Northern Province of Serbia) are presented and discussed. Aerosol, rain, fresh milk and spinach samples were collected daily in the weeks following the accident. In the aerosol samples, (131)I activity concentrations of several mBq m(-3) were measured, while in rain, milk and spinach samples, (131)I levels had values in a range of (0.3-1.7) Bq kg(-1). These are the first results on the impact of the Fukushima accident on the Pannonian basin region. Our results are compared with the reported values from other parts of the world.