Hasil untuk "Radioactivity and radioactive substances"

P. Kuzmanović, J. Radić, Branko Vujkovic et al.

Drinking water that contains elevated levels of radioactive substances can pose a potential risk for the development of cancer. Therefore, regular monitoring of radioactivity in water intended for human consumption is essential. In this context, a long-term investigation was carried out across 13 sites in the Mačva District (Western Serbia) during the 2010-2020 period. This region has notable industrial activity, including the phosphate and chemical industries. In this region, the opening of a lithium mine is planned in the near future, making it necessary to establish reliable baseline data on the radiological quality of drinking water before the start of mining activities. Gross alpha and beta activities were assessed using liquid scintillation spectrometry, while gamma spectrometry was used to determine the activity concentrations of radionuclides such as 238U, 226Ra, 228Ra, 40K, 137Cs, and 134Cs. All recorded values for alpha and beta activities remained below the regulatory thresholds of 0.1 Bq L-1 and 1 Bq L-1, respectively. Similarly, the activity concentration levels of all analyzed radionuclides complied with the recommended safety limits, resulting in an annual ingestion dose well under 0.1 mSv. Notably, no traces of radiocaesium were found in drinking water samples after the 2011 Fukushima nuclear accident. The findings indicate that the drinking water in this region poses no significant radiological threat, and that local industrial processes have not led to increased radionuclide concentrations.

Xue Zhao, Xiaolin Hou, Weijian Zhou et al.

With the acceleration of climate change, understanding the behavior of the anthropogenic radioactive substances─particularly their responses to the climate system─has become critical for assessing their transport, transfer, and impact on the ecosystems. However, this remains underexplored, particularly in the South China Sea (SCS), where radioactivity is derived from both the close-in fallout of the Pacific Proving Ground (PPG) and the global fallout. Additionally, this region is quite sensitive to climate change. A coral core collected from Xisha Island, SCS, was initially analyzed for high-radiotoxicity 239,240Pu. Approximately 72-84% of plutonium in coral originated from the close-in fallout of PPG through ocean current compared to the direct global fallout. However, the 239,240Pu concentration still remains in background levels and does not show a significant radiation risk. After 1980, a distinct pattern emerged characterized by a "higher" concentration but a "lower" 240Pu/239Pu atom ratio compared to the levels in the open west Pacific. This is primarily attributed to the seasonal upwelling of subsurface seawater on the continental shelf of SCS, driven by the prevailing southwest monsoon. Significantly elevated 239,240Pu concentrations were observed during typical ENSO years 1983, 1988, and 1997. This is due to the elevated temperature, coral bleaching, and expulsion of symbiotic zooxanthellae. After expulsion, zooxanthellae containing higher 239,240Pu compared to skeleton rapidly die, and their debris directly deposit onto the coral skeleton, in contrast to the metabolic way of 239,240Pu during normal years. This finding offers critical insights into ecosystem protection in SCS amid global changes and the potential threat of nuclear contamination.

Uku Andreas Reigo, Cansu Özcan Kilcan, A. Tkaczyk

Supplementary cementitious materials (SCMs) may be prepared using industrial byproduct streams, aiding in the development of a more environmentally sustainable circular economy. However, these byproducts may carry a risk of exhibiting elevated levels of radioactivity because of the preceding processing that may have concentrated the radionuclides naturally occurring in the raw material. This processing causes the byproducts to be considered technologically enhanced naturally occurring radioactive material (NORM). Thus, the safe use of such SCMs requires robust data on the activity concentrations of three main radionuclides (226Ra, 232Th, 40K) represented by the activity concentration index (ACI) used as a radiological suitability indicator. In this work, candidate SCMs derived from the alumina industry byproduct processed bauxite (PB), also referred to as bauxite residue, were assessed by measuring the activity of all available samples, including input raw materials and intermediate substances, through gamma spectrometry. PB was found to significantly impact the final ACI value of the building material. As a key analysis outcome applicable to the substances assessed in this work, no additional dose assessment is required, given the low ACI value of the building materials. This result indicates that, from a radiological perspective, the PB samples studied are suitable precursors for SCMs. In addition, a generalized approach was found to provide good estimations of the ACI value of building materials, which is useful to screen materials for regulatory compliance, without needing to prepare samples of the materials in question.

Kelly Pascoalino, Josemary A. C. Gonçalves, Fabio de Camargo et al.

This work investigates the influence of doping type on the dose responses and the accumulated dose stability of n- and p-type silicon MCz diodes. The operating principle of diode-based dosimeters relies on measuring the radiation-induced currents delivered by non-polarized diodes throughout the exposure time. An electrometer promptly reads the current signal, linearly dose rate dependent. The offline integration of the current signal provides the charge generated in the sensitive volume of the diode, expected to be proportional to the absorbed dose. The experimental approach involves analyzing the repeatability of the current signals, the dose responses of both pristine and pre-irradiated diodes, the correspondent charge sensitivities, and the sensitivity decay with increasing doses. For doses up to 175 kGy, the results reveal a linear dose response of the MCz(p) diode, characterized by a charge sensitivity of 3.1 µC/Gy.  Within the same dose range, the response of the MCz(n) diode is visibly saturated and given by a fourth-order polynomial function. This saturation effect is likely linked to radiation damage effects manifesting in the current decay with increasing accumulated doses. This surmise is confirmed in this work by a less pronounced drop in sensitivity of the p-type diode than that recorded for the n-type diode when both are subjected to 175 kGy. This behavior is ascribed to the working principle of the diode in the short-circuit current mode and the differences between the diffusion lengths of minority carriers in n- and p-type silicon materials. The diodes' response stability and dose lifespan remain to be further investigated.

Daniel Coiro Silva, Songeli Menezes Freire , Anderson Galvão Bueno et al.

Decreased radioactive activity to be injected in individuals for diagnostic exams performed on Positrons emission Tomography associated with Computed Tomography is becoming mandatory since the patient protection is one of the pillars for Radiation Protection.  The technological advance opens the possibility to demonstrate this activity reduction as well as time reduction during the exam, which allow a better convinience to population, and still maintaining the quality of the diagnose. This study investigates operational changes observed after the introduction of a new PET-CT scanner (PET2), focusing on reductions in administered radioactive activity and acquisition time. The results show significant decreases in these parameters compared to a prior system (PET1). The scope of the study is limited to describing these operational impacts, based on the manteinance of diagnostic image quality support by the physician criteria.

V. Yu. Golikov

The paper demonstrates the limitations of the existing methodology for calculating the radiation shielding of X-ray rooms presented in SanPin 2.6.1.1192-03. It is shown that the algorithm for calculating the attenuation coefficient by the barrier does not take into account the features of the attenuation of different components of X-ray radiation: direct, scattered, and leakage radiation, which differ in the region of occurrence, intensity, energy spectrum, and other parameters. Instead, a single formula is used for all components, and the differences in their attenuation are taken into account by a parameter the values of which for different radiation components are in no way justified and are questionable. The calculation also does not take into account the distribution of the workload of X-ray machines by the tube voltage, the significant attenuation of direct X-ray radiation by additional structures necessary for image acquisition. The values of the radiation output of X-ray machines recommended for shielding design in SanPiN 2.6.1.1192-03 are 2–3 times overestimated in relation to the measured values. This leads to an unreasonable overestimation of the requirements for the thickness of radiation shielding in X-ray rooms and accordingly to suboptimal spending on healthcare. It is necessary to develop a new document to replace SanPiN 2.6.1.1192-03.

Andressa Nery, Barbara Paci Mazzilli, Marcelo Bessa Nisti et al.

The aim of the study was to determine the activity concentration of the natural radionuclides (226Ra, 210Po, 228Ra and 40K) and artificial radionuclide 137Cs in the muscle of the marine fish species most consumed in the city of São Paulo and to evaluate the annual effective dose due to the consumption of the fish. Samples were collected in the supermarket chain Extra and Carrefour and in the distribution center CEAGESP. Six fish species were selected among the most available and consumed in São Paulo city: anchovy, tuna, dogfish, croaker, hake and sardine. After the sample preparation procedures, the determination of 226Ra, 228Ra, 40K and 137Cs was carried out by gamma spectrometry and the determination of 210Po by alpha spectrometry. The results obtained for all the species studied are below the limits adopted by the Brazilian Standards for 137Cs and, therefore, their consumption offers no risk due to the ingestion of this radionuclide. The concentration obtained for the radionuclides 226Ra, 210Po, 228Ra and 137Cs in the fish samples analized are low and of the same order of magnitude as data from literature. The results obtained for the doses, for all the species studied, showed that their consumption offers no risk of exposure due to the ingestion of the analyzed radionuclides.

A. V. Akleyev, A. A. Akleyev

The review dwells upon the problematic issues, uncertainties and prospects of establishing causal relationship between diseases and radiation exposure. The review discusses the challenges, uncertainties and prospects of establishing causation between exposure to radiation and diseases. The criteria that could be used to assess the radiation-induced health damage are considered. The existing practice of recognizing certain categories of citizens of the Russian Federation as people affected by radiation exposure, which is based on the establishing causal relationship between disease, invalidity, death with radiation exposure by Interdepartmental expert councils, is analyzed. Experts of Interdepartmental expert councils in taking the decision rely on to the list of diseases that should be updated consistently based on the findings of radio-epidemiological studies. To make the decision-making process objective, advanced scientific studies focused on individualization of the radiation risk and search for the biomarkers of radiation-induced effects, both deterministic and stochastic ones, are discussed.

Lucas Iwahara, Cláudio Pereira, Maria Angélica Wasserman et al.

The soil-plant transfer factor (Fv) is used methods in the computational models for radiological risk assessment by ingestion of radiocobalt-contaminated food. Different soil types, plants types and agricultural practices contribute to a wide dispersion of Fv values, indicating the need to study the criteria that influence root uptake in a regional view. In this scenario, Artificial Neural Networks (ANN) have become a possibility to predict Fv values based on critical pedological parameters. This work aims to apply ANN to evaluate the possibility of predicting Fv for 60Co in reference plants as a function of soil properties considered relevant for transfer processes in the soil-plant system. Through the systematic literature review, mineralogy, organic matter, texture, pH, CEC and nutrients were identified as soil properties that affect Fv values for 60Co. However, although these attributes were not always reported, still it was possible to create databases of Fv for 60Co in radish root and leaf, with pH, organic matter, and CTC as potential edaphic indicators. Learning sets were structured and due to the complexity of the search space and the small amount of available data, deep ANN with regularization (dropout) layers were required to achieve good prediction and avoid overfitting. The best model obtained showed good correlation in the validation and training set, considering the chosen parameters.

Valter Arthur, Andressa Maria Simas Albano

The irradiation of fresh post-harvest foods has as main interests: inhibit sprouting, increase shelf life, reduce or delay damage caused by insects and diseases. This work is a preliminary study on the use of gamma radiation in fresh peas grains (Pisum sativum L.) in order to evaluate its effects on the inhibition of sprout and its increase in shelf life. The peas were submitted to 4 treatments: 0 (control), 0.15, 0.30 and 0.45 kGy, in a 60 Co research irradiator, after irradiation stored at 8 °C, being evaluated at 1, 7, 14 and 21 days after irradiation, for the following analyzes: assessments of visual appearance, total soluble solids, titratable total acidity, ratio, fresh weight loss, coloring, texture, pH, water content and ash. By visual evaluation it was observed that the irradiation did not significantly change the shelf life of the grains. The visual appearance, coloring and pH had interference due to the natural process of grain maturation. The doses of gamma radiation did not influence the content of ash, water and texture during storage and that dose of 0.45 kGy was not sufficient to inhibit the sprouting of the peas. It is possible to conclude that, with this work, a recommendation that, for the later works, in which one wishes to define the shelf life or to inhibit sprouting pea, initiate the irradiation of its samples with values above 0.45 kGy.

Desirée Yael de Sena Tavares, Adilson Costa da Silva, Zelmo Rodrigues de Lima

This work proposes to implement the cell calculation considering the fuel burning using the WIMSD-5B code. The cell calculation procedure allows determining the nuclear parameters present in the multi-group neutron diffusion equation and for this purpose the neutron transport theory is used in a problem with dimensional reduction, but in contrast is considered a large number of groups associated with the neutron spectrum. There are a variety of reactor physics codes that determine the nuclear parameters by solving the neutron transport equation applied to an equivalent cell representing a fuel element. The WIMSD-5B code is a deterministic code that solves the transport equation using collision probability method. The simulation of fuel burning in the cell calculation took into account different nuclear data libraries. The WIMSD-5B code supports several nuclear data libraries and in the present work the following libraries were used: IAEA, ENDFB-VII.1, JENDL3.2, JEFF3.1 and JEF2.2, all formatted for 69 energy groups.

Kátia Pedrosa Silva, Maria do Socorro Nogueira

Computed tomography represents the largest portion of the population´s exposure to ionizing radiation related to medical imaging. This article aims to assess the quality of the images through the analysis of radiologists in routine chest protocols, performed at one hospital and two diagnostic imaging clinics, and employing three equipment with different technologies. A total of 1,088 criteria were analyzed with the three imaging techniques, and the average percentage of the observed structures were 95, 99 and 99% for each service. There was an excellent correlation between observers and even an absolute agreement in some cases for the most modern technologies. The three studied devices provided acceptable dose values and images with a quality close to 100%, reducing the exposure and improving the radiological protection of patients.

Thalita Pinheiro Sanches, Frederico Antonio Genezini, Mitiko Saiki

This study presents results of instrumental neutron activation analysis (INAA) of nails from healthy adult individuals living in São Paulo city, Brazil. Concentrations of As, Br, Ca, Co, Cr, Fe, K, La, Na, Sb, Se and Zn were determined in fingernails and toenails and their variations with gender, age, body mass index among individuals and inter-element correlations were evaluated. These results indicated that several factors might affect in the nail element composition. In addition, there are few published data for finger and toenails analyses. However, comparisons made between the concentrations of elements obtained in fingernails were reasonable within the range of literature values. The findings of this study may contribute to establish an appropriate protocol to obtain data of nail element composition to be used as reference values.

V. V. Omelchuk

The recent years are associated with active development of the coastal areas of the Russian arctic regions including a construction of the facilities of the extraction and processing of the hydrocarbons, the civil and military facilities. The nuclear weapon tests, performed by the USSR and other nuclear countries in the second half of the XX century, lead to the global radioactive fallout, including the fallout on costal areas of the arctic regions of the USSR. Five most powerful nuclear munitions were tested on the Novaya Zemlya Test Site in the Arkhangelsk region. The Institute of Radiation Hygiene after professor P.V. Ramzaev (before 1994 — the Leningrad Scientific-Research Institute of Radiation Hygiene) has accumulated a 20-year experience of the radiation-hygienic surveys on the assessment of the consequences of the nuclear weapon tests for the Far-North of the USSR: from the development of the equipment and methods for the extraction, analysis and measurement of the low levels of the radioactive isotopes in humans and environment, to the wide-scale radiation-hygienic surveys of the links in the “northern food chain” — lichen, raindeers and native inhabitants. The obtained data allowed performing a complex assessment of the role of the radiation factor in the health of the public residing on the coastal areas of the Arctic Ocean.

Seyna Ueno Rabelo Mendes, Marina Beatriz Agostini Vasconcellos, Marilia Gabriela Miranda Catharino et al.

ABSTRACT   The objective of the work is to evaluate the mercury exposure of children living in an artisanal gold mining area and in a control area, without mining. A cross-sectional study was conducted with children living in the municipalities of Chapada de Natividade and Porto Nacional, in the State of Tocantins, where hair samples were collected for laboratorial analysis of mercury concentrations, comparing between municipalities, gender, monthly fish consumption, profession of parents and the presence of amalgam in dental restorations. The hair samples were analyzed by the methods of neutron activation analysis and also by means of the DMA (Direct Mercury Analyzer) equipment, in the last case being a partnership with CETESB. There was no evidence of mercury-related diseases in the studied children. The mean concentration of mercury in children in Chapada de Natividade was significantly higher than in Porto Nacional. Children exposed to artisanal gold mining areas have higher concentrations of mercury than children living in non- artisanal gold mining areas. There was no significant relationship between mercury concentrations and gender, monthly fish consumption, parental profession and amalgam presence in dental restorations. The results suggest that the children living in an area exposed to mining experience greater environmental exposure to mercury, regardless of their eating habits.

Vanderley Vasconcelos, Wellington Antonio Soares, Raissa Oliveira Marques et al.

Non-destructive inspection (NDI) is one of the key elements in ensuring quality of engineering systems and their safe use. This inspection is a very complex task, during which the inspectors have to rely on their sensory, perceptual, cognitive, and motor skills. It requires high vigilance once it is often carried out on large components, over a long period of time, and in hostile environments and restriction of workplace. A successful NDI requires careful planning, choice of appropriate NDI methods and inspection procedures, as well as qualified and trained inspection personnel. A failure of NDI to detect critical defects in safety-related components of nuclear power plants, for instance, may lead to catastrophic consequences for workers, public and environment. Therefore, ensuring that NDI is reliable and capable of detecting all critical defects is of utmost importance. Despite increased use of automation in NDI, human inspectors, and thus human factors, still play an important role in NDI reliability. Human reliability is the probability of humans conducting specific tasks with satisfactory performance. Many techniques are suitable for modeling and analyzing human reliability in NDI of nuclear power plant components, such as FMEA (Failure Modes and Effects Analysis) and THERP (Technique for Human Error Rate Prediction). An example by using qualitative and quantitative assessesments with these two techniques to improve typical NDI of pipe segments of a core cooling system of a nuclear power plant, through acting on human factors issues, is presented.

M. Lersow, P. Waggitt

F. Ahmadabad, Behrouz Rasuli, Raheleh Tabari Juybari et al.

D. Molin, F. Georges

T. Adeeko, E. Ajala, H. Ogbochukwu