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This study deals with the design of the checkpoint system for monitoring the environmental radioactivity in the vicinity of the nuclear reactors. As the design site was selected the Vinča Institute of Nuclear Sciences in the capital city of the Republic of Serbia. There are situated two former nuclear research reactors with potential hazardous materials in controlled conditions. Due to the high risk of ecosystem contamination in the vicinity of various nuclear facilities such as reactor, radiological analyses of coastal soils, sediments and stream/river water were performed at the selected checkpoints. The investigation included determination of gross alpha and gross beta activities, gamma spectrometric analysis and analysis of 90Sr content in the collected environmental samples, as well as determination of 3H activity concentration, but only in water samples. Gross alpha activity ranged from 0.013 Bq/L to 0.057 Bq/L for water samples, from 130 Bq/kg to 280 Bq/kg for soil samples, and from 120 Bq/kg to 270 Bq/kg for sediment samples. Gross beta activity ranged from 0.128 Bq/L to 0.332 Bq/L for water samples, from 850 Bq/kg to 1600 Bq/kg for soil samples, and from 660 Bq/kg to 1200 Bq/kg for sediment samples. The main contribution to gamma radiation in water samples was made by 40K and 137Cs. The 226Ra/238U ratio ranged from 0.37 to 1.24 in soil and from 0.51 to 1.16 in sediment. 90Sr and 3H were detected in all studied samples. The presented results and the increased radiation risk in the above mentioned area show that the surrounding of the nuclear reactors and the exposure of the population to ionizing radiation must be constantly monitored.

Jedan od značajnih načina kontrole rada termoelektrana (TE) na ugalj je kontinuirano praćenje vrednosti koncentracija aktivnosti radionuklida prirodnog porekla sadržanih prvenstveno u uglju, a potom i uzorcima pepela i šljake kao glavnim produkatima sagorevanja uglja koje je zbog svoje obilne proizvodnje neophodno odlagati na deponije otpada. Koncentracije aktivnosti prirodnih radionuklida 238U, 235U, 226Ra, 210Pb, 232Th i 40K, koje bi u životnoj sredini potencijalno mogle biti preraspodeljene kao posledica rada TE, podležu redovnoj kontroli u uzorcima uglja, šljake, elektrofilterskog pepela, kao i u uzorcima sakupljenim sa deponija pepela, na aktivnoj i pasivnoj kaseti, i zemljištu uzorkovanom na manjoj i većoj udaljenosti od TE. Predmet ovoga rada je analiza rezultata višegodišnjih merenja obavljenih u periodu od 2010. do 2022. godine. Godišnje vrednosti koncentracija aktivnosti izmerene za svaki ispitivani radionuklid i svaku od sedam vrsta uzoraka posmatrane su kao hronološki nizovi podataka koji čine diskretne vremenske serije za koje su rezultati statističke analize ukazivali da se mogu opisati kao procesi tzv. belog šuma., One of the most important means of controlling the operation of coal-fired power plant (CFPP) is the continuous monitoring of naturally occurring activity concentrations of radionuclides contained primarily in coal and, consequently, in ash and slag samples, the main coal combustion products that must be disposed of in landfills due to their high production. The activity concentrations of the naturally occurring radionuclides 238U, 235U, 226Ra, 210Pb, 232Th, and 40K, which could potentially be released into the environment as a result of the CFPP operation, are regularly monitored in the samples of coal, slag, and fly ash, as well as in the samples of ash piles on the active and passive cassettes and in the soil sampled at lesser and greater distances from the CFPP. The aim of this work is to analyse the results of the multi-year activity concentration measurements carried out in the period from 2010 to 2022. The annual activity concentration values measured for each studied radionuclide and each of the seven sample types were observed as a chronological sequence of data forming discrete time series, which, according to the results of statistical analysis, may be described as white noise processes.

MetroPOEM (Metrology for harmonization of measuremenets of environmental pollutant in Europe) je trogodišnji evropski projekat finansiran u okviru EMPIR programa.Globalna težnja ka što manjem zagadjenju (European Green Deal´s ambition for zero pollution) zahteva razvoj visoko osetljivih tehnika kojima se mogu detektovati niske koncentracije polutanata. Masena spekrometrija je najznačajnija tehnika za odredjivanje neradioaktivnih, ali i dugoživućih radioaktivnih polutanata. Glavni cilj ovog projekta je da uspostavi vezu izmedju radiometrijskih i masenih tehnika merenja polutanata. Takođe, cilj projekta je i smanjenje mernih nesigurnosti, limita detekcije, ali i razvoj novih referentnih materijala kojima bi se obezbedila sledivost mernih procedura., The MetroPOEM project (Metrology for harmonization of measurements of environmental pollutants in Europe) is a three-year European project financed under the EMPIR program. The global aspiration towards as little pollution as possible (European Green Deal's ambition for zero pollution) requires the development of highly sensitive techniques that can detect low concentrations of pollutants. Mass spectrometry is the most important technique for determining non-radioactive, but also long-lived radioactive pollutants. The main goal of this project is to establish a link between radiometric and mass pollutant measurement techniques. Also, the goal of the project is the reduction of measurement uncertainties, detection limits, but also the development of new reference materials that would ensure the traceability of measurement procedures.

In this work, the thermal decomposition process of coal bottom ash (collected after lignite combustion in coal-fired power plant “Kostolac B” (TEKO-B), Serbia) was investigated, using simultaneous TG (thermogravimetry) – DTG (derivative thermogravimetry) techniques in an inert (Ar) atmosphere, at various heating rates (10.3, 20.9 and 32.1 K/min). In addition to thermal characterization of the sample, the chemical composition and naturally occurred radionuclides were also determined. Using the model-free (isoconversional) (by Friedman (FR), Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW) and Vyazovkin (VY) methods) analysis, the complex kinetic nature of the process was successfully resolved. The conducted numerical optimization of the process (using non-linear least square optimization) had confirmed accuracy and reliability of estimated kinetic parameters. Model-based (model-fitting) kinetic analysis showed the existence of a complex reaction scheme, over two consecutive reactions steps and one single-stage reaction step, via mechanism order An, F2, Fn, R3, Cnm (through n-dimensional nucleation/growth, chemical reactions, and n-th order and m-power with autocatalysis mechanisms). Through physicochemical interpretation of mechanism scheme, an assessment of recovery of valuable metals and metal oxides was performed, by analysing the concentration of reaction species in a function of temperature of individual steps. Likewise, the influence of certain precursor involved in decomposition process as catalyst (in order to increase the yield of targeted product) was also inspected. Finally, the simulation of actual process using the results obtained from applied methods/models was performed, through application of modulated dynamic (MD) prediction.

Determination of specific activity concentration of radioisotopes in environmental samples can be used to assess the long-term kinetics of the decline of radioisotopes. Based on the obtained activity concentrations of tritium in the Danube, the effective ecological half-life is estimated. Assuming that the Danube in Belgrade is not affected by nuclear power plants, even though it is positioned downstream of the Paks Nuclear Power Plant in Hungary, a slow decline of tritium was observed. The effective ecological half-life of tritium was also determined after correction by subtracting its components originating from cosmic radiation and the atmospheric transfer from nuclear facilities worldwide.

This paper presents the results for gross alpha and gross beta activity in leaves samples: Fig (Ficus carica), Vine (Vitis vinifera L.), and Apricot (Prunus armeniaca). Samples were collected in Iraq (Sulaymaniyah, Kurdistan region), and in the Serbia (Belgrade), in the summer 2018. The analysis was done in dried and milled samples as well as in the annealed samples, using gas flow proportional counter. Determination of gross alpha and gross beta activity presents rapid method, essential for the analysis of radioactivity in environmental samples. The gross alpha activity is defines as the total activity of alpha emitters, and originates from the decay chains of 238U and 232Th, which quantity depends on the geological and geographical formation of natural radionuclides. The main contributor to the gross beta activity is natural long-lived isotope 40K, as well as 210Pb, 228Ra. The gross beta measurements also include a contribution from anthropogenic radionuclides 137Cs and 90Sr. Radionuclides that emitting low-energy beta radiation (3 H and gaseous or volatile radionuclide such as iodine) cannot be detected by gross beta activity measurements.

This paper presents distribution and seasonal variations of tritium, radioactive isotope of hydrogen, in Sava River in Belgrade. Tritium besides its natural origin also has an artificial origin, through human activity including the operation of nuclear power plants, nuclear weapons manufacturing and atomic bomb tests. Knowing the concentration of tritium in the Sava River in Belgrade is important because it is located downstream from the Krško Nuclear Power Plant in Slovenia. Analysis of tritium concentrations in surface water samples were done in composite monthly samples during 2017-2022. Tritium activity was determined by liquid scintillation spectrometer using electrolytic enrichment. Seasonal variations were estimated by determination of average monthly concentrations and seasonal indices.

Measurement of radon (222Rn) concentration using charcoal filters according to the EPA 520/5-87-005 method is performed in Radiation and Environment Protection Department of Vinča Institute for Nuclear Sciences on NaI scintillation detectors. Concentration of radon adsorbed on active charcoal is determined indirectly, by gamma spectrometry of its daughter products via their gamma peaks at 295 keV, 352 keV (214Pb) and 609 keV (214Bi). In order to assure the reliability of the measurement results, and in accordance with Standard ISO 17025/17 quality control and quality assurance (QA/QC) procedures needs to be applied. Related activities ought to be planned, described in the quality control documentation, performed in a systematic manner, recorded and reviewed. First, the energy and efficiency calibration of the detection system needs to be performed in a proper manner. The NaI scintillation spectrometer is internally calibrated using the certified radioactive 226Ra standard in charcoal matrix and in the geometry identical to the measurement geometry, produced by Czech Metrology Institute and traceable to Bureau International des Poids et Mesures (BIPM). As defined in laboratory’s procedures a regular quality control of the NaI scintillation detector is performed once a week. Quality control activities include the background measurement and measurement of adequate reference material. Gross background count rate in the energy region of interest is used to verify that the detector and shield have not been contaminated and that there is no significant variation of the background. Reference material used is the soil sample with known content of 226Ra. Gross count rate in the reference material spectrum is used to check the energy and efficiency calibration. These values are recorded and verified if they are within the acceptance limits. Obtained results, together with acceptance limits, for a certain period (one year usually) is graphically presented in the control charts.

As a part of regular activities of the accredited laboratory, the Laboratory for Radiation Measurements of the Radiation and Environmental Protection Department, Institute Vinča, every year takes part in the proficiency tests organized by IAEA. This year, within the framework of IAEA – TERC – 2022 – 01/02 Proficiency Test, one of the requests was to measure the simulated surface contamination using the instrument that are at the disposal in the participant laboratories. The results should be reported in the units of counts/s/cm2 in order to be comparable. In this paper, the measurement method and subsequent specific calculations for the simulated surface contamination are explained and the results of the proficiency test stated and discussed.

U radu je prikazana procena stanja u životnoj sredini Mokre Gore, posmatrano sa radioekološkog aspekta. Rezultati gamaspektrometrijskih merenja sprovedenih na germanijumskom detektoru visoke čistoće su pokazala prisustvo 226Ra, 232Th i 40K u zemljištu Mokre Gore u koncentracijama aktivnosti: od 10 Bq/kg do 20 Bq/kg za 226Ra, 13 Bq/kg do 34 Bq/kg za 232Th i 96 Bq/kg do 250 Bq/kg za 40K. Na osnovu rezultata gamaspektrometrijskog merenja aktivnosti navedenih primordijalnih radionuklida, izvršena je procena radijacionog rizika usled terestričkog izlaganja stanovništva na području Mokre Gore. Proračunom su procenjeni sledeći parametri radijacionog rizika: ukupna jačina doze gama zračenja (srednja vrednost 28,6 nGy/h), godišnja efektivna doza (srednja vrednost 0,035 mSv) i indeks radijacionog rizika usled spoljašnjeg izlaganja (srednja vrednost 0,169). Procenjene vrednosti navedenih parametara ukazuju na to da ne postoji uvećan radijacioni rizik za stanovništvo ispitanog područja usled terestričkog izlaganja.

Gasni proporcionalni brojač koristi se za određivanje ukupne alfa i ukupne beta aktivnosti u različitim matriksima kao i za određivanje aktivnosti antropogenog radionuklida 90Sr koji je čist beta emiter. Ovaj rad predstavlja pregled kontrole kvaliteta gasnog proporcionalnog brojača Thermo-Eberline FHT 770T i određivanja efikasnosti, koja se sprovodi sa sertifikovanim standardima 241Am i 90Sr. Brojač ima mogućnost simultanog merenja na 6 detektora i određivanja aktivnosti reda mBq. U radu su prikazani i rezultati sprovedene eksterne kontrole kvaliteta učešćem u interkomparativnom merenju 90Sr, ukupne alfa i ukupne beta aktivnosti u uzorcima vode, organizovanom od strane Međunarodne Agencije za Atomsku Energiju tokom 2022. godine.

Mjerenja koncentracije aktivnosti radionuklida Be-7 (berilij-7), Pb-210 (olovo 210) i Cs-137 (cezij-137) u Zemljinoj atmosferi neophodna su za razumijevanje atmosferskih procesa, kvalitete zraka i radioaktivnosti okoliša. Berilij-7 je radioaktivni izotop koji prvenstveno nastaje interakcijom kozmičkih zraka s atomima dušika i kisika u gornjoj atmosferi. Njegov kratki poluživot čini ga vrijednim tragačem za atmosferske procese u relativno kratkim vremenskim razdobljima. Olovo-210 je radioaktivni izotop čiji je primarni izvor u atmosferi raspad plina radona. S dužim poluživotom od Be-7, pogodan je za proučavanje dugotrajnijih atmosferskih procesa. Cezij-137 je, s druge strane, antropogeni radioizotop s vremenom poluraspada čak i dužim od onog Pb-210, što ga čini dobrim dugoročnim ekološkim tragačem. Nedavno je uspostavljena baza podataka za praćenje radioaktivnosti tla u zraku (GRAMON). Sadrži rezultate mjerenja radioaktivnosti u površinskom zraku na sedam lokacija: Beograd (Srbija), Ljubljana i Krško (Slovenija), Sarajevo (Bosna i Hercegovina), Podgorica (Crna Gora), Skopje i Bitola (Sjeverna Makedonija). Naš rad daje statističku analizu mjesečnih (prosječnih) vrijednosti koncentracija aktivnosti radionuklida za svaku lokaciju od 2010. do 2019. Rezultati pokazuju prostorne razlike i vremensku evoluciju radioaktivnosti zraka u ovoj regiji koja je obično nedovoljno zastupljena u velikim studijama., Measurements of activity concentrations of radionuclides Be-7 (beryllium-7), Pb210 (lead210), and Cs-137 (cesium-137) in the Earth’s atmosphere are essential for understanding atmospheric processes, air quality, and environmental radioactivity. Beryllium-7 is a radioactive isotope produced primarily by cosmic ray interactions with nitrogen and oxygen atoms in the upper atmosphere. Its short half-life makes it a valuable tracer for atmospheric processes on relatively short timescales. Lead210 is a radioactive isotope whose primary source in the atmosphere is decay of radon gas. With a longer half-life than Be-7, it is suitable for studying longerterm atmospheric processes. Cesium-137, on the other hand, is an anthropogenic radioisotope with a half-life even longer than that of Pb-210, which makes it a good long-term environmental tracer. The Ground Air Radioactivity Monitoring (GRAMON) database has been recently established. It contains the outcomes of radioactivity measurements in the surface air at seven locations: Belgrade (Serbia), Ljubljana and Krško (Slovenia), Sarajevo (Bosnia and Herzegovina), Podgorica (Montenegro), Skopje and Bitola (North Macedonia). Our paper gives a statistical analysis of monthly (average) values of the radionuclides’ activity concentrations for each location from 2010 to 2019. The results demonstrate spatial differences and temporal evolution of air radioactivity over this region commonly underrepresented in large-scale studies.

U ovom istraživanju analizirana je fraktalna priroda vremenske serije specifične aktivnosti berilijuma-7 u površinskom sloju atmosfere u Beogradu, Srbija, sa ciljem da se prouči dinamika njene samosličnosti, a s posebnim fokusom na godišnji ciklus. Korišćene su metode vejvlet analize i vremenski zavisne detrendovane pokretne srednje vrednosti radi identifikacije karakterističnih intervala i procene Hurstovih eksponenata. Podaci o specifičnoj aktivnosti berilijuma-7 preuzeti su iz GRAMON baze podataka, za lokaciju Beograd (44,88 °N; 20,58 °E; 95 m nadmorske visine). Vremenska serija obuhvata 362 mesečna merenja od 1991. do 2022. godine. Rezultati ukazuju na postojanje izraženog godišnjeg ciklusa u ovoj vremenskoj seriji. Takođe, promene u lokalnom Hurstovom eksponentu otkrivaju varijacije u ponašanju vremenske serije – ona iz umereno korelisanog prelazi u izrazito antikorelisan proces između 2015. i 2020. godine. Ovaj rezultat biće predmet šire analize koja uključuje i druge lokacije iz GRAMON baze podataka.

U radu je razmatran potencijalni odnos između dobijenih rezultata za koncentraciju tricijuma u kišnici i rekama, Savi i Dunavu, u Beogradu. Uzorkovanja su vršena svakog meseca tokom 2021. godine. Svi uzorci su koncentrisani primenom metode sa elektrolitičkim obogaćenjem, dok je za detekciju tricijuma korišćen tečni scintilacioni spektrometar. Dobijeni rezultati korišćeni su za izračunavanje količine tricijuma deponovane po m2 površine, kao i prosečnog toka tricijuma u rekama na osnovu protoka vode. Dobijena distribucija tricijuma tumačena je u skladu sa meteorološkim i hidrološkim parametrima., The potential relationship between the obtained results for the tritium concentration in precipitation and in the Sava and Danube River in Belgrade was analyzed. Sampling was done during 2021. All samples were concentrated using the method with electrolytic enrichment, while a liquid scintillation spectrometer was used for tritium detection. The obtained results were used to calculate the amount of tritium deposited per m2 of surface as well as to estimate the average flow of tritium in rivers based on river water flow. The obtained distribution of tritium was interpreted in accordance with meteorological and hydrological parameters.

Sprovedeno istraživanje je usmereno na analizu trenda promene ukupne alfa i ukupne beta aktivnosti u poljoprivrednom zemljištu i usevima višegodišnjeg oglednog polja. Analiza je urađena primenom akreditovane metode za određivanje ukupne alfa i ukupne beta aktivnosti u čvrstim matriksima. Merenja su obavljena u Laboratoriji za zaštitu od zračenja i zaštitu životne sredine Instituta za nuklearne nauke “Vinča” na niskofonskom gasnom proporcionalnom brojaču Thermo Eberline FHT 770T. Izmerene vrednosti ukupne alfa aktivnosti variraju od 158 Bq/kg do 324 Bq/kg i ukupne beta aktivnosti od 600 Bq/kg do 1324 Bq/kg za uzorke zemljišta. Za uzorke biljnih kultura vrednosti ukupne alfa aktivnosti su u intervalu od 5 Bq/kg do 167 Bq/kg suve materije, dok su vrednosti ukupne beta aktivnosti u intervalu od 180 Bq/kg do 584 Bq/kg suve materije. Rezultati istraživanja su značajni, jer daju osnovne radiološke informacije od vitalnog značaja za ispitivano područje. Ovo je prvi pokušaj generisanja osnovnih podataka o radijacionom opterećenju zemljišta i biljnih kultura poljoprivrednog ekosistema alfa i beta emiterima, koji su određeni skrining metodom za monitoring životnog okruženja., The conducted research is focused on the analysis of the trend of changes in gross alpha and gross beta activity in agricultural soil and crops of perennial experimental fields. The analysis was performed using an accredited method for determining gross alpha and gross beta activity in solid matrix. The measurements were performed in the Radiation and Environmental Protection Department in Vinča Institute of nuclear Sciences on a low-level gas proportional counter Thermo Eberline FHT 770T. The measured values of gross alpha activity varied from 158 Bq/kg to 324 Bq/kg, and from 600 Bq/kg to 1324 Bq/kg for the gross beta activity in soil samples. For plant samples, values ranged from 5 Bq/kg to 167 Bq/kg of dry matter, and from 180 Bq/kg to 584 Bq/kg of dry matter for gross alpha and gross beta activity, respectively. The results of the research are significant, because they provide basic radiological information of vital importance for the investigated area. This is the first attempt to generate data base on the radiation load of soil and crops of the agricultural ecosystem with alpha and beta emitters, which were determined by the screening method for environmental monitoring.

Oko pola efektivne doze koju stanovništvo primi usled izlaganja jonizujućem zračenju potiče od radona i njegovih potomaka, te je problematika radona važna u oblasti zaštite od zračenja. Takođe, kao hemijski inertan gas, radon je našao primenu u izučavanju životne sredine kao traser za razne geološke i atmosferske procese. Jedna od važnih primena radona je u problematici praćenja gasova koji izazivaju efekat staklene bašte (greenhouse gases – GHG). Pokazano je da se poznavanjem fluksa radona iz zemlje i priraštaja koncentracije radona i koncentracije GHG u istom vremenskom intervalu tokom noći može odrediti fluks GHG. U ovom radu će biti prikazani odabrani rezultati nedavno završenog traceRadon projekta čiji je cilj bio razvijanje metrološki sledivih metoda merenja niskih koncentracija radona u atmosferi u granicama od 1 Bq m-3 do 100 Bq m-3, kao i unapređenje tehnika merenja i samo merenje radonskog fluksa, što će doprineti ispitivanju klimatskih promena kroz obezbeđivanje pouzdane procene fluksa GHG. Takođe, u sklopu projekta, vršila se procena do koje mere se radon u spoljašnjoj sredini i radonski fluks mogu koristiti za procenu radonskih prioritetnih oblasti., Since more than a half of the effective doses from all ionising radiation come from the exposure to radon and its progeny, radon is important in the field of radiation protection. Being a noble gas and therefore chemically inert, radon is also used as a tracer for different geological and atmospheric processes. Radon is of interest to climate scientists for monitoring greenhouse gasses (GHG). It is known that by knowing radon flux and variation of radon and GHG concentration at the same period of time during the night, it is possible to estimate emission of GHG. In this paper, the most important results of recently finished EMPIR project 19ENV01 traceRadon “Radon metrology for use in climate change observation and radiation protection at the environmental level” are presented. Project aimed to develop the capability to measure SI traceable radon activity in the range of 1 Bq m-3 to 100 Bq m-3, suitable for outdoor radon measurements, to develop the capability for traceable radon flux measurements in the field which is important for GHG emission estimates and validation of contemporary radon flux models. Within the project it was investigated to what extent radon flux and outdoor radon data could be used for estimation of radon priority areas.

Rutinska merenja uzoraka iz životne sredine gama spektrometrijom zahtevaju pripremu radioaktivnih standarda različitih matriksa. Radioaktivni standardi se koriste u svim fazama procesa merenja, uključujući validaciju metoda, kalibraciju i kontrolu kvaliteta. U Laboratoriji za Zaštitu od zračenja i zaštitu životne sredine, Instituta za nuklearne nauke „Vinča” radioaktivni standardi se pripremaju korišćenjem sertifikovanog radioaktivnog rastvora različitih radionuklida. U ovom radu je opisan postupak pripreme radioaktivnih standarda koji obuhvata izbor matriksa, pripremu i spajkovanje pripremljenih matriksa sa sertifikovanim radioaktivnim rastvorom, proveru homogenosti, pakovanje standarda u odgovarajuću geometriju i njihova merenja u kontakt geometriji na gama spektrometru. Za sve materijale matriksa pripremljeni su i uzorci „blenka“ i mereni u istoj geometriji kao i kalibracioni standardi. Nakon analize snimljenih spektara, fitovanjem datih tačaka efikasnosti dobijene su kalibracione krive. U ovom radu dat je i opis budžeta merne nesigurnosti za aktivnosti radionuklida prisutnih u pripremljenim standardima., The routine measurements of environmental samples using gamma-ray spectrometry indicate the needs for preparing radioactive standards for various matrices. The radioactive standards are used in all phases of the measurement process, including method validation, calibration and quality control. In the Radiation and Environmental Protection Departmen in the "Vinča" Institute of Nuclear Sciences, radioactive standards are prepared using a certified radioactive solution of mixed radionuclides. The procedure for radioactive standards preparation, which includes matrix selection and preparation, spiking with a certified radioactive solution, homogeneity check, matrix packing in the appropriate geometry and measurement of the prepared standards using a gamma spectrometer, is described in this paper. For all matrix materials, "blank" samples were prepared in the same manner as the standard materials and measured in the same geometry as the calibration samples. After the analysis of recorded spectra and evaluation of the obtained data for efficiency at given energies, calibration curves were obtained by fitting. The uncertainty budget of the activity for all radionuclides present in the prepared standards is also defined in this paper.

Tritium levels in natural waters today have a similar value to the concentration before thermonuclear bomb testing conducted between 1954 and 1963. Because of the low concentration of this radioisotope, the analysis requires enrichment techniques to produce low detection limit, accurate results and to reduce uncertainties. This analysis includes preliminary distillation, electrolytic enrichment of the samples, the second distillation, and measurement on ultra low-level liquid scintillation spectrometer. The enrichment system consists of 16 electrolytic cells, each with a capacity of 250 ml, placed in the freezer and connected to a direct current source. One cell contains spike water with known tritium concentration and is used for enrichment factor determination. The initial volume for all samples is 250 ml. Na2O2 is used as an electrolyte to make the solution alkaline. Each cell has a gas outlet to ensure the escape of gases H2 and O2. In order to obtain a high enrichment factor, the system works on 5 A, to reduce the initial volume of the samples by 10-15 times. After electrolysis, second distillation must be performed to eliminate electrolyte. 8 ml of water sample after the second distillation is mixed with a scintillation cocktail in polyethylene vials and measured on a liquid scintillation spectrometer Quantulus 1220. At the end of the electrolytic enrichment process, the final volumes of the samples can be different, which causes different enrichment between the cells. To eliminate this influence, the final volume of all enrichment samples can be normalized at one value. In order to determine the corrected count rates obtained for each sample, the separation factor must be first calculated, taking into account initial volume, normalized final volume, count rate for spike water (after enrichment), count rate for spike water (before enrichment), and background count rate. In the example of one electrolysis, with 15 samples of drinking water, precipitation, and s

Ground Air Radioactivity Monitoring (GRAMON) database is a recently established collection containing activity concentrations of gamma emitters in aerosol samples. The measurements come from Serbia (sampling site Belgrade), Slovenia (sampling sites Ljubljana and Krško), Bosnia and Herzegovina (sampling site Sarajevo), Montenegro (sampling site Podgorica), and North Macedonia (sampling sites Skopje and Bitola), thus covering the northern and central parts of the Balkan Peninsula. As a database arising from the monitoring programmes in several countries, GRAMON is not fully homogeneous in terms of the radionuclides and time periods studied. For example, the beryllium-7 records are available for all sampling sites, while the lead-210 records only in Serbia, Slovenia, and Bosnia and Herzegovina. The time series for Serbia and Slovenia began in 1991, for Montenegro and North Macedonia in 2008, and for Bosnia and Herzegovina in 2010. However, sampling, sample preparation, and measurement procedures across the sites and laboratories are similar. In brief, aerosol samples are collected on filter papers using air samplers. Activity concentrations of radionuclides are determined by standard gamma spectrometry using high-purity germanium detectors. The time series contain monthly mean activity concentrations. Since only some of the GRAMON records have been previously published, this database provides a source for radioactivity research in the region that has been underrepresented in large-scale studies. We further hope to expand the number of contributing laboratories and cover a wider region of Europe, especially its southern and eastern parts.

This work presents the natural radioactivity distribution of 21 surface soil samples taken in the city of Novi Sad, Serbia. The analysis for radioactivity was performed using a gas low-level proportional counter for gross alpha and gross beta activity, while the specific activities of radionuclides were determined using HPGe detectors. The gross alpha activity of 20 samples was below the minimum detectable concentration (MDC), while in 1 sample it was 243 Bq kg−1; the gross beta activity ranged from the MDC (11 samples) to 566 Bq kg−1. The gamma spectrometry measurements showed naturally occurring radionuclides 226Ra, 232Th, 40K, and 238U in all investigated samples, with average values (Bq kg−1) of 33.9, 36.7, 513.8, and 34.7, respectively. Natural radionuclide 235U was detected in 18 samples with activity concentrations in the range of 1.3–4.1 Bq kg−1, while in the other 3 samples, the values were below the MDC. The artificial 137Cs radionuclide was detected in 90 percent of the samples, with a maximum value of 21 Bq kg−1, while the other artificial radionuclides were not detected. Based on the obtained concentrations of natural radionuclides, hazard indexes were estimated, and radiological health risk was assessed. The results present the absorbed gamma dose rate in the air, annual effective dose, radium equivalent activity, external hazard index, and lifetime cancer risk.

Doses from the exposure to outdoor radon are typically an order of magnitude smaller than those from indoor radon, causing a greater interest on investigation of the latter for radiation protection issues. As a consequence, assessment of radon priority areas (RPA) is mainly based on indoor radon measurements. Outdoor radon measurements might be needed to guarantee a complete estimation of radiological risk and may help to improve the estimation of RPA. Therefore, authors have analysed the available literature on outdoor radon to give an overview of outdoor radon surveys and potential correlation with indoor radon and estimation of RPA. The review has shown that outdoor radon surveys were performed at much smaller scale compared to indoor radon. Only a few outdoor radon maps were produced, with a much smaller density, covering a larger area, and therefore putting doubt on the representativeness of this data. Due to a large variety of techniques used for outdoor radon measurements and requirement to have detectors with a high sensitivity and resistance to harsh environmental conditions, a standardised measurement protocol should be derived. This is no simple endeavour since there are more applications in different scientific disciplines for outdoor radon measurements compared to indoor radon.

Metodom gamaspektrometrije u periodu 2020-2021. godina praćena je koncentracija aktivnosti radionuklida u površinskoj vodi i rečnom sedimentu reke Dunav, na teritoriji beogradske opštine Zemun. U ovom radu su prikazane vrednosti izmerenih koncentracija aktivnosti detektovanih radionuklida. Dok se u uzorcima površinske vode praktično detektuje samo prisustvo 40K i 226Ra u koncentracijama reda nekoliko desetina mBq/l, u uzorcima sedimenta detektovani su prirodni radionuklidi u navedenim opsezima koncentracija : 226Ra - (14-46) Bq/kg, 232Th - (17-56) Bq/kg, 40K - (230-645) Bq/kg, 238U - (15-53) Bq/kg i 235U - (1,2-3,2) Bq/kg.

The operation of coal fired power plants greatly influences the surrounding environment, especially water and soil, due to large amounts of combustion waste products released. Besides the quality of soil and water from the aspect of chemical and structural composition (release of heavy metals, ash and slag deposition on soil) it is of at most importance to maintain a strict control from the radiological safety point of view. All coal types contain certain amount of naturally occurring radionuclides, which depends on the composition of the rock and soil adjacent to the place of the coal excavation. These radionuclides are concentrated in the process of coal combustion, thus leading to potentially high levels of radioactivity in the ash and slag. These by – products are released into the environment and can increase the radiation burden on the environment, change the composition of the soil and bodies of water in the vicinity, thus potentially influencing the health of the general population. In this paper, the radiological analysis of soil and water samples taken from the vicinity of different coal fired power plants in Serbia in the period of 2019-2021. will be presented. Measurements are performed in the Radiation and Environmental Protection Department of Institute of Nuclear Sciences Vinča within the framework of regular environment monitoring of the power plants.

Radiostrontium is released to the environment during the testing and use of nuclear weapons mainly in the fifties and sixties of XX century, in addition to nuclear power plant accidents (to some extent in 1986 owing to the Chernobyl accident) and the nuclear fuel reprocessing industry. Strontium is a chemical analogue of calcium (both are earth-alkaline metals) and accordingly when entering a human or animal body, it behaves similar to calcium. A large portion of the strontium will accumulate in bone and teeth and then is included in the metabolism along with Ca, and like calcium, it transfers to milk. Since the strontium uptake by the human body from milk is an important pathway for radiostrontium incorporation, milk and dairy products are good indicators of strontium-90 (Sr-90) content in human diet. Based on the mentioned, the knowledge about Sr-90 content in milk and dairy products is of extreme importance to prevent and control contamination of the food chain. The present study was conducted in order to radiologically control for Sr-90 content in raw milk and some dairy products samples composed of representative locally purchased milk. The analyses are performed using radiochemical analytical oxalate precipitation method, whereby interfering radionuclides are removed by precipitation scavenging. Yttrium-90 (Y-90) is generated from the beta decay of Sr-90. After the ingrowth Y-90 is separated and equilibrium is established, the samples are measured by gas flow proportional counter. The results of investigation showed that Sr-90 activity concentration in many investigated samples was at a lower level than minimum detectable activity (MDA) of the method.

After the Chernobyl accident, the presence of artificial radionuclides in foodstuff, especially in berries (blueberries, cranberries etc.), was heightened. Legislative, presented in Rulebook on Radioactivity Control of Goods During the Import, Export and Transit (Official Gazette RS, 86/19 and 90/19), establishes the mandatory gamma spectrometry measurement of berries, while the limits of radionuclide content in these products is defined in the Rulebook on Limits of radionuclide content in drinking water, foodstuff, feedstuff, medicines, items of general use, building materials and other goods placed on the market (Official Gazette RS, 36/18). At the Radiation and Environment Protection Department of the Vinča Institute of Nuclear Sciences, measurements of the radionuclide activity in foodstuff are readily performed. In this paper, the results of the investigation of berries in the period of 2014 to 2021 are presented along with the amount of this produce that can be ingested by the various age groups without exceeding the annual effective dose limit of 0.1 mSv.

In accordance with ISO/IEC 17025:2017 - General requirements for the competence of testing and calibration laboratories, the laboratory needs to verify its ability to properly perform methods before introducing them, by ensuring it can achieve the required performance (article 7.2.1.5). Also, if a laboratory carries out a sampling of a material, it needs to have a sampling plan and method established (article 7.3.1). In laboratories dealing with radionuclide content testing, the sampling does not affect the testing results directly, but the sampling procedure has to ensure that the taken and later measured sample adequately represents the tested material. In order to verify the sampling procedure for the needs of radiological tests, a sampling of red mud (13 samples) and bauxite ore (6 samples) was conducted in the aluminum factory “Alumina ltd”, Zvornik, Bosnia and Herzegovina in June 2021. In accordance with the established sampling procedure, GPS coordinate and ambient dose rate were recorded for each sample. Samples were prepared in accordance with IAEA, TRS 295 (1989), placed into identical PVC cylindrical boxes and measured by HPGe gamma spectrometer. Spectra of bauxite and red mud were recorded in 10 consecutive measurements for 21000 s and 6000 s, respectively, in order to achieve good statistic. For the purpose of sampling procedure verification, the counting rates per unit mass in the recorded spectra were compared. For each measurements series, the total counts in the spectrum as well as individual energies mean value and standard deviations were calculated. After the measurements were completed, the average of the each individual series mean values and the associated/corresponding standard deviation were calculated. The measurement result of each individual series is considered satisfactory if, taking into account the calculated standard deviation, it is within +/- two standard deviations of the average of the mean values. The obtained results verified t

Tritium, radioactive isotope of hydrogen, is produced naturally in the upper atmosphere between nitrogen atoms with high energy cosmic rays. Anthropogenic production has disturbed the natural levels of tritium by nuclear atmospheric tests between 1945 and 1963. Tritium is a pure beta emitter with half-life of 12.32 years. Since the main way to eliminate tritium from the atmosphere is through precipitation, whether of natural or artificial origin, tritium easily reaches surface waters and soil from where it can infiltrate into the groundwater and thus enters in the hydrological cycle. Accordingly, knowing the concentration of tritium in precipitation is of essential importance. This paper presents determination of tritium in precipitation collected at Reference Meteorological Station Zeleno Brdo in Belgrade during 2019. Analysis is done in composite monthly samples. Sample preparation involves the first distillation, electrolysis and the second distillation. Samples were measured by Liquid Scintillation Spectrometer Quantulus 1220 after electrolytic enrichment by mixing 8 ml of sample with 12 ml of scintillation cocktail. Tritium activity concentration in analyzed precipitation samples follows normal seasonal variations with maximum in spring-summer months. Based on the monthly amount of precipitation, that is available on the website of the Republic Hydrometeorological Servise of Serbia, it is possible to estimate the deposition of tritium on the earth's surface. The wettest months of 2019 were May and June, and since tritium concentrations are the highest in these months (June: 2.89 Bq/l), the highest value of deposited tritium is obtained in June: 400,8 Bq/m2 . In accordance with the legislation in the Republic of Serbia, the permitted values of tritium are defined only for drinking water (100 Bq/l). An elevated tritium level may indicate the presence of other artificial radionuclides. If an increased activity of tritium is detected, it is necessary to perform an

Mountain ecosystems are going through changes due to numerous physical-chemical processes in the environment rather than the anthropogenic activities. Primordial radioactivity of rock and soil material migrates and fractionates in other environmental sections like waters, air and biota. Having a feature to accumulate different minerals and trace element present in soil and three substrates, fungi indicates their composition and related processes. The aim of this study is uptake of radionuclides by fungi in the schist soil of the Stara Planina, mountain famous for biodiversity as well as for enhanced natural radioactivity areas. Samples of various fungi species (stipes and cups) and their soil substrates have been collected in summer season 2019. Collected soil samples are pedologically characterized and analysed by gamma-spectrometry (HP Ge) after the secular radioactive equilibrium had been reached. Soil characterization has shown the share of coarse fragments, sand, silt and clay in the schist (shale) structure while pH value was 4.80-5.33 and organic carbon content 3.10%. The content of significant natural radionuclides 40K, 226Ra, 232Th, 238U and manmade 137Cs was (in Bq/kg) was 500±30, 27±2, 26±2, 32±4, 1.6±0.2 respectively. Dried fungi samples were analysed by gamma spectrometry showing the natural radionuclide content in wide range of values. Obtained results indicate dependence of the radionuclides uptake from the substrate on their abundance in schist soil type as well as the fungus specie physiology. Slight difference was observed in results between content in species with different types of nutrient uptake (mycorrhizal and saprobic). The 137Cs content varied from 2-20 Bq/kg. Further knowledge on the local population habits in use of edible fungi species would enable dose assessment for the representatives of the public and contribute to a further research on the Stara Planina mountain ecosystem.

In accordance with ISO/IC 17025:2017 testing laboratory shall have a procedure for monitoring the validity of results that includes regular participation in interlaboratory comparisons. Interlaboratory comparison RADON2021 was organized in the frame of the bilateral project between Serbia and Montenegro: “Measurement of the radon equilibrium factor in typical residential buildings in Serbia and Montenegro and harmonization of radon measurement techniques” in order to assess congruence of different measurement techniques, and then harmonize methods in case of inconsistencies. Harmonization is of particular importance to neighboring countries, in order to avoid inconsistencies in the classification of radon risk zones along border areas. Thus, six regional laboratories took part in the intercomparison – three from Belgrade and one from Novi Sad, Serbia; one from Podgorica, Montenegro; one from Banja Luka, Bosnia and Herzegovina. All laboratories participated in the indoor radon measurements, while 4 laboratories measured radon in the soil also. The measurement methods and detectors used by the laboratories were: • for air - EPA 402-R-92-004 – Indoor Radon and Radon Decay Product Measurement Devices Protocols, ch. 3.1. with RAD 7, RTM1688-2 and RadonEye; EPA 520/5-87-005 – 1987 EERF Standard Operating Procedures for Rn-222 Measurement Using Charcoal Canisters, ch. 3.4 using adsorption on charcoal canisters; ISO 11665- 4: Measurement of radioactivity in the environment – Air Radon 222: Part 4: Integrated measurement method for determining average activity concentration using passive sampling and delayed analysis with Electretes, and • for soil gas - ISO 11665-11:2016 Measurement of radioactivity in the environment — Air: radon-222 — Part 11: Test method for soil gas with sampling at depth by using active devices RTM1688-2 and RAD 7. The measurements were performed in real conditions where the radon concentration varied following a typical daily variation. Indoor radon c

Beryllium-7 is a natural radionuclide used as a tracer of the stratospheric-tropospheric exchange. Its abundance in the surface air is expected to change as the temperatures in the atmosphere increase. To investigate the temporal trends of the beryllium-7 activity concentrations and temperature, we apply spectral analysis to time series from three sampling sites: Belgrade in Serbia, and Ljubljana and Krško in Slovenia. The sites lie close to the 45 ºN parallel, with Krško approximately 400 km and Ljubljana around 500 km west of Belgrade. Between January 1991 and December 2019, the air filter samples were collected using air samplers; a monthly composite sample was formed and analysed by gamma spectrometry. We use monthly mean temperature records from the European Climate Assessment & Dataset, the Republic Hydrometeorological Service of Serbia for Belgrade, and the Slovenian Environment Agency for the sites in Slovenia. In the spectral analysis decomposition, we look into a term called trend that represents the overall growth (increase or decrease) in the data records. The trend is calculated using a linear fit. All three sites show 1) positive temperature trends, however statistically insignificant (at the 95 % confidence level), and 2) statistically significant beryllium-7 activity concentration trends of 2.26 %/year, 1.13 %/year, and 0.50 %/year in Belgrade, Ljubljana, and Krško, respectively. The results confirm our initial hypothesis–over the 28 investigated years, the beryllium-7 activity concentrations increase in the surface air. On the other hand, the non-significant temperature rise in our records suggests that within our method, the temporal resolution of one month is insufficient for obtaining a statistically significant temperature trend.

Radon flux measurements provide information about how much radon rises from the ground toward the atmosphere, thus, they could serve as good predictors of indoor radon concentrations. Although there are many different mapping methods with many different input data, radon flux data are generally missing and are not included for the delineation of radon priority areas (RPA). The aim of this literature review is to investigate to what extent radon flux was used, or could be used, for the delineation of RPAs. Numerous factors influencing radon flux were identified, but quantifying their contribution to radon flux measurement still remains a challenge. Different methods and measuring devices were used for the determination of radon flux, thus it is necessary to identify possible inconsistencies in order to harmonise different radon flux measurements. Due to the complexity of radon flux measurements, only two countries were identified to have performed national surveys on outdoor radon, which were of much smaller scale compared to those on indoor radon. A positive correlation between radon flux and radon quantities, such as radon in soil gas and indoor radon, indicates that radon flux could be used as an input parameter for the estimation of RPA. By reviewing radon flux models, it was concluded that up-to-date modelled radon flux maps have reached excellent spatial resolution and will be further improved, hence, they could serve as an input for the estimation and delineation of RPA.