High Concentrations Of Natural Radionuclides Research Articles

Assessment of the mobility of potentially toxic trace elements (PTEs) and radionuclides released in soils stabilized with mixtures of bentonite-lime-phosphogypsum.

Phosphogypsum (PG) is a solid by-product of the phosphate industry, rich in contaminants and produced in large quantities. Raw materials and stabilized specimens, consisting of bentonite-lime-PG mixtures, were characterized by mineralogical, microstructural, chemical, alpha-particle, and gamma-ray spectrometry analysis before hydration and after hardening. Compressive strength and leaching tests were performed on hardened specimens. The physicochemical parameters and chemical composition of leachates from raw materials and hardened specimens were determined. PG contains high concentrations of natural radionuclides, specially from U series. Uranium-238 activities are double in PG than the worldwide average for soil values. The mobility of PTEs from PG is Cd (2.43%), Zn (2.36%), Ni (2.07%), Cu (1.04%), Pb (0.25%), and As (0.21%). Cadmium is the cation most easily released by PG in water with a concentration 0.0316mgkg-1. When PG is added to bentonite-lime mixture, cadmium is no longer released. The radionuclide 238,234U and 210Po predominates in the leachates of PG. However, the activity of 210Po becomes negligible in the leachates of bentonite-lime-PG mixtures. The addition of PG to bentonite-lime mixtures facilitates the trapping of trace elements (PTEs) and radionuclides, providing potential applications for PG as road embankments and fill coatings.

Phase and structural investigations of the content of natural radionuclides in rock and inorganic building materials

The population living in areas rich in granites, minerals and soils with high concentrations of natural radionuclides is exposed to higher external radiation. Significant part of a person's time resides in buildings where he lives and works. The walls, floors and roofs of the buildings shield (weaken) the external gamma background. The aim of the work is to determine the content of natural radionuclides in rock and inorganic materials used as building materials of samples taken from different buildings in Southern Bulgaria by analysing the samples and measuring their natural radioactivity, then to compare the results with the maximum concentrations of activity in common building materials. also used in the EU.The data obtained from the analyzes do not give grounds to expect the generation of radionuclides from natural and conventional inorganic building materials used in the studied areas.

Radiological characteristics of Self-Compacting Concretes incorporating fly ash, silica fume, and slag

This article presents the results of a comprehensive study investigating the hypothesis that higher concentrations of natural radionuclides, that are harmful to human health, may be present in Self-Compacting Concretes (SCCs) due to its higher powder material content compared to conventional concretes. The fresh (slump-flow, T500 time, V-funnel) concrete and compressive strength of SCCs prepared by replacing Portland cement with fly ash (FA), silica fume (SF), and ground granulated blast furnace slag (GGBFS) in the respective range of 5%, 12.5%, and 20% were determined. The radionuclide activity concentration of all solid concrete components and SCCs were determined using the gamma spectrometry method. Radioactivity analyses including the calculation of the activity concentration index and annual effective dose equivalents were also performed. The findings showed that the specimens with the highest average compressive strength at the end of 120th day were, respectively, SF (54.2 MPa), FA (52.2 MPa) and GGBFS (46.1 MPa) added to the SCC. The obtained concentration of the Radium-226 value (41.1) of 20% UK with added SCC was 1.8 times higher than the control concrete (22.7) and 2 times higher than 20% SF added SCC (19.7). The highest Radium equivalent activity (Raeq) values were FA20 (89.52), GGBFS20 (72.05), control concrete (70.86) and SF20 (68.01). It was determined that the FA selected for the study exceeded the limit specified for structural material (3.38 > 1) and fell in the radiologically hazardous class. It has been proven that SF can be used as a radioactivity reducing material of concretes. The results revealed that the research hypothesis was confirmed in terms of FA.

Assessment of natural irradiation doses in rare earth mines of Muong Hum, Bat Xat district, Lao Cai province

The rare earth mine containing high concentrations of natural radionuclides (238U, 232Th, and 40K) in Muong Hum commune, Nam Pung, Bat Xat district, Lao Cai province, a mine with large reserves of rare earth resources in Vietnam, will be exploited and processed in the near future. The activity of natural radionuclides in the environment of air, soil, water, and effective annual dose are important parameters in assessing the impact of radiation on the environment when the mine goes into operating and processing rare earth ore. Investigating and determining radioactivity in soil, water, and plants at Muong Hum rare earth mine by means of radioactive gas measurement (RAD-7), gamma radiation dose rate (DKS-96), sample analysis using an ICP-MS mass spectrometer, will be performed in this study. The results showed that some soil samples had radionuclides activity 238U, 232Th higher than the allowed standard. The annual effective dose value in the region is 6.1 times higher than the world average (2.4 mSv/year). The obtained results are the basis for monitoring the impact of the radioactive environment and providing solutions to minimize the effects of radioactive substances on the ecological environment when the mine goes into mining and processing of rare earth ores.

Estimation of Occupational Exposure during Ceramic Manufacturing

Introduction: The present study investigated the relatively high concentrations of natural radionuclides in raw material that used in ceramic manufacturing, and estimated the occupational exposure due to these activity concentrations. Material and Methods: A high-purity Germanium detector was used to determine naturally occurring radionuclides in raw materials that used in ceramic manufacturing. Activity concentrations of these materials lead to potential radiological hazards due to gamma and alpha radiation. These hazards were evaluated in the present study. Results: Maximum activity concentrations was5844, 1065 and 41 Bq/kg for 226Ra, 232Th and 235U in powdered quartz; however, maximum activity concentration for 40K was 1868 Bq/kg in colors. These activities were observed to be exceeding the exemption limit. Pancreasreceived the lowest dose (i.e., 0.02 mSv/y), while skin received the highest dose (i.e., 0.044mSv/y). Internal hazard index (Hin) was reported as 53.74, which exceed the recommended value (Hin≤1). Alpha index was 42.4 which led to over exposure. Representative level index and excess lifetime cancer risk were 0.00062 and 0.641 respectively. The total annual external dose was 2.62 m Gy/y which led to 1.83 mSv/y effective dose. Radiological hazard due to radon inhalation was 1.53E-06 mSv/y. Conclusion: Due to the high activity concentrations of raw materials (especially zirconium compounds) and consequently the associated high dose, specific regulations must be applied in the ceramic industry in Egypt.

Terrestrial Gamma Radiation Exposure in Bangka-Belitung Islands, Indonesia

Bangka-Belitung is known as tin producer and it geologically contains higher concentrations of natural radionuclides than most other areas. The aim of this study was to evaluate the level of terrestrial gamma radiation in Bangka-Belitung Islands. The external gamma radiation dose rate from terrestrial gamma-rays have been measured at one meter above the ground by means of a portable gamma spectrometer at 66 survey points. The terrestrial gamma dose rates in Bangka island range from 43.67 to 511.54 nGy h -1 with a mean of 183.45 nGy h -1 , while in Belitung island they range from 15.54 to 416.39 nGy h -1 with a mean of 132.60 nGy h-1. From this work, a strong correlation was found between dose rates found from in-situ radiation measurements and dose rates calculated theoretically from radioactivity contents of the soil at the same locations. Generally, Bangka-Belitung islands have higher outdoor natural gamma dose rates than the world average value of 0.058 μGy h -1 for the regions with normal background radiation specified by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Received: 27 August 2014; Revised: 05 March 2015; Accepted: 30 March 2015

The migration of radionuclide’s for the sanitary protection zone of uranium tailings enterprises (LB488)

Mining companies are potential sources of contamination of the environment by various pollutants, including technogenic radionuclides. Stepnogorsk Mining‐Chemical Combine (SMCC) functions over 50 years and is one of the largest complexes for production of uranium oxide and other rare metals. Radioactive waste of SMCC is accumulated in the tailing dumps with an area of 7.82 km2, located in 4 km to the North from Aksu village and Zavodskoy, where concentrated waste is with a mass of 44.17 million tons, and activity of 146.4 thousand Ku. The aim of this work was to evaluate the radiological situation of territories for sanitary protection zone of the tailings dumps (SZZH), including those in close vicinity to workers of the villages Aksu and Zavodskoy.As a result of the pedestrian gamma survey there were identified local, contaminated sites in the North‐East of SZZH SMCC with a length of 5 km. The most contaminated with radionuclides is the top layer of the soil 0‐5 cm. in the North‐East and South‐East direction from SZZH specific activity is 238U, 226Ra in the soil exceed the reference value in 16 times, 210Pb exceeds up to 7 times. In the samples of plants selected from the vicinity of villages in the South‐East and North‐East directions from SZZH it is noted high concentrations of natural radionuclides. In reservoirs of Sulukamys and Manybay thalwegs, located at a distance of 1.5 to 2 km in the Eastern and North‐Eastern part of the tailings dumps, the specific activity of technogenic radionuclides in the tens times higher than control values.On the territory of the village Aksu there were identified local, contaminated sites with a capacity of an equivalent dose of gamma radiation up to 0.86 mSv / h Possible additional radiation dose from external exposure for separate groups of the population of Aksu is from 0,86 mSv to 1,53 mSv per year.

Natural radioactivity of ground and hot spring water in some areas in Yemen

Water from bedrock frequently contains higher concentrations of natural radionuclides than water from other sources. Groundwater from Assalamia-Alhomira and Juban areas (southeast of Sana'a) and hot spring water from Dempt area (south Sana'a) in Yemen were analyzed for 226Ra, 232Th and 40K activity concentrations. The average activity concentrations for groundwater from Assalamia–Alhomira area were 4.04 Bql−1 and 1.81 Bql−1 for 226Ra and 232Th, respectively, while 40K was not detectable, while that for groundwater samples from Juban area were 2.95 Bql−1, 0.72 Bql−1 and 34.9 Bql−1 for 226Ra, 232Th and 40K, respectively. On the other hand, the activity concentrations for hot spring water from Dempt area were 3.48 Bql−1, 1.01 Bql−1 and 16.05 Bql−1 for 226Ra, 232Th and 40K, respectively. Also annual effective dose equivalent of ingestion of these waters was calculated. The results showed that the annual dose equivalent obtained in the present study was much higher than the recommended value (0.1mSvyear−1) as reported by WHO. The results were compared with those for drinking water.

Applying gross alpha and beta measurements as an estimate to the total indicative dose of Cambrian-Vendian ground water in Estonia

Gross alpha and beta measurements are common procedures for screening water samples in order to estimate the level of total indicative dose (TID) from the radionuclides in water. However, it has been pointed out that gross alpha and beta measurements are not suitable for waters containing high concentrations of natural radionuclides, especially Ra-226 and Ra-228. Cambrian-Vendian aquifer system is the major source of public water supply in northern and north-eastern Estonia. The aquifer is known for its high radionuclide concentrations. The main sources of TID are Ra-226 and Ra-228, but the water also contains K-40. Other nuclides from uranium and thorium series may be present as well. A set of Ra-226, Ra-228 and K-40 activity concentrations measured by gammaspectrometry are studied to analyze the applicability of gross alpha and beta measurements in case of Cambrian-Vendian ground water. The calculations indicate that the levels suggested by WHO guidelines are not suitable for the Cambrian-Vendian ground water. Results on the applicability analysis are given.

NORM in the extraction industry: Challenges and opportunities

One of the most serious problems occurring during coal extraction in Upper Silesia in Poland is caused by waters with high salinity which also often contain high concentrations of natural radionuclides, mainly 226 Ra and 228 Ra. Similar phenomenon is also observed in oil and gas industry. On the Norwegian continental shelf, substantial amounts of produced waters containing elevated levels of 226 Ra and 228 Ra are discharged to the sea. All of these facts outlined elsewhere in the reports serious resulted in contamination of wide areas surrounding mines and other related industries. Research studies conducted so far have provided a lot of data concerning the scale of this phenomenon. But nowadays, all of them should be reconsidered in the light of newest recommendation of the state of-the-art radiation protection. Namely, such waste deposited directly into the environment creates significant risk to the non-human biota that currently must be assessed as well. On the other hand, such scenario of exposure to ionising radiation creates a good opportunity to observe potential effects of low and protracted doses to the living organisms occurring on contaminated areas, especially plants.

Well water radioactivity and risk of cancers of the urinary organs

Water from bedrock frequently contains higher concentrations of natural radionuclides than water from other sources. Bladder and kidneys receive a radiation dose when radioactive isotopes are excreted into urine. The subjects for this case–cohort study were selected from all drilled wells users in Finland. The study comprised 61 bladder cancer and 51 kidney cancer cases diagnosed between 1981 and 1995, as well as a random sample of 274 reference persons, stratified by age and sex. The median activity concentrations of radon in drilled wells used by bladder and kidney cancer cases and the reference cohort were 170, 140, and 130 Bq/L, respectively. The radium concentration was 0.01 Bq/L for all groups and the uranium concentrations were 0.08, 0.07, and 0.06 Bq/L, respectively. The bladder cancer risks associated with radon, radium, and uranium activity concentrations in drinking water were 1.02 (0.68–1.54) per log(100 Bq of radon/L), 0.73 (0.21–2.50) per log(0.1 Bq of radium/L), and 0.77 (0.32–1.89) per log(1 Bq of uranium/L). The corresponding figures for kidney cancer were 0.81 (0.47–1.37), 0.12 (0.01–1.10), and 0.92 (0.36–2.35), respectively. In conclusion, even though ingested radionuclides from drilled wells are a source of radiation exposure, they are not associated with a substantially increased risk of bladder or kidney cancers in concentrations occurring in drilled wells.

Contamination caused by radium discharged with mine effluents into inland waters

One of the most serious problems occurring during coal extraction in Upper Silesia in Poland is caused by waters with very high salinity. These waters often contain also high concentrations of natural radionuclides, mainly 226 Ra from uranium series and 228 Ra from thorium series. At least 70% of the total amount of radium carried by this waters remains nowadays in underground galleries as radioactive deposits. But, during the period of the most extensive coal extraction up to 225 MBq of 226 Ra and 400 MBq of 228 Ra were released daily into surface along with the other mine effluents. As a result of discharge of radium-bearing waters into settling ponds and later into rivers a significant increase of radium concentration in bottom sediments has been observed. Sometimes there is also a contamination of river beds, soils and biota. The paper describes results of investigation of waters and sediments with enhanced natural radioactivity, that occur in settling ponds, where mine waters have been dumped. Measurements of different factors of radiological hazard were made, such as radium content in the soil from ponds' banks, variations of gamma radiation background and radon exhalation. Additionally radium transfer to vegetation that had transgressed into the ponds has been calculated.

Photon attenuation, natural radioactivity content and radon exhalation rate of building materials

High concentrations of natural radionuclides in building materials can result in high dose rates indoors, from both internal and external exposure. In dose calculations, the main radionuclides of interest are 226Ra, 232Th and 40K. Usually much attention is paid to 226Ra due to 222Rn exhalation and the subsequent internal exposure. Other radionuclides of the uranium series such as 238U and 210Pb, emitting low energy photons are not usually determined and an assumption of radioactive equilibrium is made. The above assumption is seldom checked mainly because of the difficulties in the γ-spectroscopic analysis of low energy photons. For the determination of radionuclides emitting low-energy photons, in samples like building materials where intense self-absorption of the photons exists, a method for self-absorption correction has been developed. The method needs as input the linear attenuation coefficient μ for the material under analysis. This paper presents: 1. Correlations in the form μ= f( ρ, E) developed for the estimation of the linear attenuation coefficient μ (cm −1), as a function of the material packing density ρ (g cm −3) and the photon energy E (keV), for building materials as well as other materials of environmental importance. 2. Gamma-spectroscopic analysis techniques used for the determination of 238U, 226Ra, 210Pb, 232Th and 40K in environmental samples, together with the results obtained from the analysis of building materials used in Greece, and industrial by-products used for the production of building materials. Among the techniques used, one is based on the direct determination of 226Ra and 235U from the analysis of the multiplet photopeak at ∼186 keV. 3. Results from radon exhalation measurements of building materials such as cement and fly-ash and building structures conducted in the radon chambers in our Laboratory. Based on the above results, dosimetric calculations are also reported.

Root absorption of 222Rn and its transfer into above-ground plant organs.

Experimental data are given on the content of genetically related pairs of radionuclides (226Ra and 222Rn; 224Ra and 220Rn) in soils and the above-ground phytomass of plants growing on plots with differing genesis of the higher concentrations of natural radionuclides in soils. Methods for determining gaseous radionuclides in the above-ground phytomass are described. Different transport routes of 222Rn and 220Rn into above-ground plant organs are considered. The noted absence of balance between 222Rn and 226Ra in plants as well as higher 222Rn/226Ra ratios in the above-ground phytomass as compared to that of the root-containing soil layer (25- to 185-fold) appears to be accounted for by the root pathway of 222Rn uptake and transport of this radionuclide to above-ground plants organs. The existence of the root pathway for 222Rn uptake is proved by direct observations of daily radionuclide movement with bleeding sap in experiments on pumpkins. For the short-lived Rn isotopes, 220Rn and 219Rn, the root pathway of uptake and transport to the above-ground phytomass is less probable, and this causes a notable redistribution of gaseous radionuclides during their movement along the soil-plant route.

Radiation protection aspects of the use of zircon sand

Working processes using zircon sand in a factory producing refractory material were studied from the point of view of radiation protection. Zircon sand contains high concentrations of natural radionuclides and is a typical example of an enhannced source. Using various techniques the characteristics of the original material were anlysed and environmental radioactivity was measured in the different significant points of the process. Finally, a first assessment was made of effective dose equivalent values in the areas of highest risk.