Hasil untuk "Radioactivity and radioactive substances"

Xuanpeng Xiao, Panpan Qi, Gongming Yu et al.

In the Coulomb and Proximity Potential Model (CPPM) framework, we have investigated the cluster radioactivity and alpha decay half-lives of superheavy nuclei. We study 22 different versions of proximity potential forms that have been proposed to describe proton radioactivity, two-proton radioactivity, heavy-ion radioactivity, quasi-elastic scattering, fusion reactions, and other applications. The half-lives of cluster radioactivity and alpha decay of 41 atomic nuclei ranging from 221Fr to 244Cm were calculated, and the results indicate that the refined nuclear potential named BW91 is the most suitable proximity potential form for the cluster radioactivity and alpha decay of superheavy nuclei since the root-mean-square (RMS) deviation between the experimental data and the relevant theoretical calculation results is the smallest (σ= 0.841). By using CPPM, we predicted the half-lives of 20 potential cluster radioactivity and alpha decay candidates. These cluster radioactivities and alpha decays are energetically allowed or observable but not yet quantified in NUBASE2020.

A. M. Antunes, B. M. Mendes, P. L. Squair et al.

The spectra measured with cadmium telluride (CdTe) detectors show high spectral distortions that must be corrected by applying a mathematical algorithm along with the detector's response functions. Simplified computational modeling of the CdTe detector is generally used to obtain its response functions. In this work, the Monte Carlo code MCNPX was used to study the response functions of a CdTe detector using more complex detector modeling and compared it with those obtained by simplified modeling. Raw spectra were corrected using the response matrices obtained for the simplified and detailed modeling of the CdTe and compared with those obtained with reference-validated software.

Dong-Meng Zhang, Lin-Jing Qi, Hai-Feng Gui et al.

In the present work, we systematically study the spectroscopic factor of proton radioactivity ($S_p$) with $A>100$ using the deformed two-potential approach (D-TPA). It is found that there is a link between the quadrupole deformation parameter of proton emitter and $S_p$. Based on this result, we propose a simple analytic formula for estimating the spectroscopic factor of proton radioactivity. With the help of this formula, the calculated half-lives of proton radioactivity can reproduce the experimental data successfully within a factor of 2.77. Furthermore, we extend the D-TPA with this formula for evaluating the spectroscopic factor to predict the proton radioactivity half-lives of 12 proton radioactivity candidates whose radioactivity is energetically allowed or observed but not yet quantified in NUBASE2020. For comparison, the universal decay law for proton radioactivity (UDLP) and the new Geiger-Nuttall law (NG-N) are also used. It turns out that all of the predicted results are basically consistent with each other.

Jozef SABOL, Lukáš HABICH

The excessive presence of radionuclides in foodstuffs can potentially pose health risks. Under normal conditions, the content of radioactive substances in food is very low, resulting in only a small fraction of the total dose caused by natural radiation. This may be substantially different in the case of radiological accidents or terrorist attacks, resulting in increased levels of radioactivity in the environment, which may contribute significantly to the radioactivity of food. The situation must be monitored to assess the contribution of internal exposure coming from ingesting contaminated food. The paper discusses the occurrence of radioactivity in various foods, including its origin and effect on the total population exposure due to radioactive contamination of the environment following the use of WMDs (Weapons of Mass Destruction). To minimise the potentially harmful consequences of such events, the radioactivity in food has to be controlled. The probability of threats of possible radiological attacks in the contemporary geopolitical situation has recently increased.

Yuki Sato

Radioactive substances released during the accident at the Fukushima Daiichi Nuclear Power Station (FDNPS) were deposited on various equipment and building structures. During decommissioning, an investigation of the radioactive substances deposited inside the contaminated equipment and structures can provide information regarding the cause and progression of the accident. This study introduces a quantitative evaluation method for the amount of radioactivity. In this method, a Compton camera, a type of gamma-ray imager, is used to investigate the deposition and contamination level of radioactive substances on contaminated objects. Multiple 137Cs radiation sources with different radioactivities were placed horizontally in one dimension within the field of view of the Compton camera, and a proof-of-principle study was conducted to evaluate the amount of radioactivity of each source quantitatively.

Abdelkarim Bazza, Mohammed Rhiyourhi, Ayoub Marhou et al.

W. Adebisi, Ifedayo Olukemi Adeojo, Taiwo Temitope Adeojo et al.

The Fukushima Daiichi nuclear disaster happened in Japan long ago in 2011, and it resulted in the emission of radioactive substances into the atmosphere. These substances were transported by air currents and were detected in several parts of the world, including Nigeria. In the aftermath of the event, it has become necessary to determine the spatial distribution of radioactivity within Osun state. This present study aims to investigate and identify areas of high gamma radiation in Osun State. This study utilised a Garmin GPS and a Geiger Muller counter radiation detector over the entire state. This study presents a radiation map of Osun state. It shows that the region has an elevation range of 190 m to 600 m, and the elevation chart shows that in comparison to the extreme south of the research region, the extreme north is distinguished by high heights. The average ionising radiation within the state ranges from 0.08 to 0.3l µSv/hr. Places including Ila, Boluwaduro and Obokun recorded the highest elevation, which in turn also had the highest dose of gamma radiation, while Ife North, Ife South, Isokan, and Irewole axis recorded their lowest figures of elevation and also had low doses of gamma radiation. The average annual effective dose rate was 0.33 mSvy-1 which is greater than 0.07 mSvy-1 for outdoor exposure. Therefore, it is important to take appropriate safety measures by wearing protection shields to avoid or minimise exposure to high levels of gamma radiation.   Keywords: Fukushima Daiichi, Gamma Radiation, Geiger Muller Counter, Radiation Map, Annual Effective Dose

Mohammad Haghparast, L. Darvish

Background: Tobacco use has remained a significant public health challenge worldwide due to its strong association with various cancers. One of the little-known factors contributing to tobacco-related cancers is the presence of naturally occurring radioactive substances in tobacco leaves. These naturally occurring radionuclides, such as radium-226, actinium-228, bismuth-214, and radium-228, originate from soil and fertilizers used in tobacco growing. Materials and Methods: In this review study, articles were collected from Medline, PubMed, Scopus, and Google Scholar search engines using keywords: "natural radioactivity," "tobacco," "cancer development," "cigarette," "smoking," "cancer," "carcinogenesis," "radioresistance," and "radiotherapy." Articles were searched without a time limit. The inclusion criteria were articles written in English and having full-text availability. Results: The studies demonstrate a strong correlation between smoking and side effects of cancer treatment. These effects are not limited to specific cancer types but have been observed across various malignancies and therapies. Conclusion: The carcinogenic mechanism of tobacco is very diverse and complex, involving both chemical and radiobiological factors. Understanding these mechanisms can help develop sensitive methods to identify signature carcinogens in tobacco, facilitating effective and targeted epidemiological studies.

Roland Diehl, Nikos Prantzos

The description of the tempo-spatial evolution of the composition of cosmic gas on galactic scales is called 'modelling galactic chemical evolution'. It aims to use knowledge about sources of nucleosynthesis and how they change the composition of interstellar gas, following the formation of stars and the ejection of products from nuclear fusion during their evolution and terminating explosions. Sources of nucleosynthesis are diverse: Stars with hydrostatic nuclear burning eject some of the products, and core-collapse supernovae add ejecta. Binary interactions lead to sources such as thermonuclear supernovae and kilonovae. Tracing ejecta from sources, with their different frequencies and environments, through the interstellar medium and successive star formation cycles is the goal of model descriptions. A variety of formalisms exist, from analytical through semi-analytical, numerical or stochastic approaches, gradually making descriptions of compositional evolution of cosmic matter more realistic, teaching us about the astrophysical processes involved in this complex aspect of our universe. Radioactive isotopes add important ingredients to such modelling: The intrinsic clock of the radioactive decay process adds a new aspect to the modelling algorithms that leads to different constraints on the important unknowns of star formation activity and interstellar transports. Several prominent examples illustrate how modelling the abundances of radioactive isotopes and their evolution have resulted in new lessons; among these are the galaxy-wide distribution of 26Al and 60Fe, the radioactive components of cosmic rays, the interpretations of terrestrial deposits of 60Fe and 244Pu, and the radioactive-decay daughter isotopes that were found in meteorites and characterise the birth environment of our solar system.

S. Etuk, I. Umoh, U. Robert et al.

Practical demonstrations by teacher and learner, especially in Science Education, make teaching-learning process pragmatic, learner-centred, easier to understand, and more appreciated. Also, it has been observed that radioactivity is one of the important topics in Physics and Chemistry at Secondary School levels. Unfortunately, its concept appears abstract and illusion in the minds of the learners due to lack of practical demonstrations or experimentation of the theory. The reason for such deficiency may be attributed to hazardous nature of radioactive substances, strict legal regulations on their exposures (both at the international and domestic levels), associated risk during transportation and handling, etc. The essence of this research is to devise a way of practically demonstrating radioactivity by utilising a non-radioactive substance that is cheaply available with high level of sustainability and potential to exhibit decay. Specifically, methylated spirit was used as the non-radioactive substance in this study. It was put in a syringe clamped vertically with an open end facing up and timing of its evaporation was performed separately for intervals of 10 minutes and 15 minutes. In each case, the volume of the methylated spirit left was recorded and the data obtained were analysed It was observed that the volume – time relationships were of exponential decay characteristic supported by empirical formula governing radioactivity, notwithstanding the time intervals considered. For 10 minutes interval consideration, the results showed evaporation constant (which is analogous to decay constant), and half-life to be 8.14 x 10-4 min-1, and 851.4 minutes respectively whereas in the case of 15 minutes interval, they were found to be 8.40 x 10-4 min-1, and 825.0 minutes respectively. Hence, it could be adjudged that methylated spirit is a promising non-radioactive substance for practical experiment/demonstration to make teaching and learning of radioactivity learner-centred for a better understanding of the topic in Physics and Chemistry at Secondary School levels.

Andréa Vidal Ferreira, Ana Carolina Araujo Bispo, Christiane Silva Leite et al.

Small animals, such as mice, are used in radiopharmaceutical biodistribution studies and innumerous others preclinical investigations involving ionizing radiation. Longitudinal preclinical studies with five or more image procedures, involving radiopharmaceuticals injection and/or X-radiation, are not uncommon. However, a suitable dosimetric evaluation is not always available and, sometimes, absorbed doses in animal organs or tissues and their influence in experimental results were not appropriately taken into account. Accurate calculation of absorbed doses in mice organs are needed to evaluate potential radiobiological effects that may interfere with in vivo experiments. In this work, we perform a preliminary 16α-[18F]-fluoro-17β-estradiol (18F-FES) radiation dosimetry estimates for female mice. The obtained animal dosimetric results can be useful for evaluating animal doses during the design of longitudinal preclinical studies.

Roland Diehl

Radioactive decay of unstable atomic nuclei leads to liberation of nuclear binding energy in the forms of gamma-ray photons and secondary particles (electrons, positrons); their energy then energises surrounding matter. Unstable nuclei are formed in nuclear reactions, which can occur either in hot and dense extremes of stellar interiors or explosions, or from cosmic-ray collisions. In high-energy astronomy, direct observations of characteristic gamma-ray lines from the decay of radioactive isotopes are important tools to study the process of cosmic nucleosynthesis and its sources, as well as tracing the flows of ejecta from such sources of nucleosynthesis. These observations provide a valuable complement to indirect observations of radioactive energy deposits, such as the measurement of supernova light in the optical. Here we present basics of radioactive decay in astrophysical context, and how gamma-ray lines reveal details about stellar interiors, about explosions on stellar surfaces or of entire stars, and about the interstellar-medium processes that direct the flow and cooling of nucleosynthesis ashes once having left their sources. We address radioisotopes such as $^{56}$Ni, $^{44}$Ti, $^{26}$Al, $^{60}$Fe, $^{22}$Na, $^{7}$Be, and also how characteristic gamma-ray emission from the annihilation of positrons is connected to these.

Tâmara Porfíro Teixeira, César Marques Salgado

As incrustações podem ser definidas como compostos químicos inorgânicos, inicialmente insolúveis, e que se precipitam se acumulam na parede interna de tubos, equipamentos de superfície e / ou partes de componentes envolvidos na produção e transporte de petróleo. Esses compostos, ao precipitarem, causam problemas na indústria do petróleo e consequentemente resultam em perdas na otimização do processo de extração. Apesar da importância e do impacto da precipitação desses compostos no âmbito tecnológico e econômico, ainda existe a dificuldade em determinar métodos que possibilitem a identificação e quantificação da escala em um estágio inicial. O uso da técnica de transmissão gama pode fornecer subsídios para um melhor entendimento da deposição desses compostos, tornando-o uma ferramenta adequada para a determinação não invasiva de sua deposição em dutos de transporte de petróleo. A geometria usada para a detecção de incrustações inclui um tubo de aço de 280 mm de diâmetro contendo escama de sulfureto de bário (BaSO4 ) variando de 5 a 60 mm, uma fonte de radiação gama com feixe divergente e como detector de cintilação NaI (Tl) 2x2 ”. O tamanho da abertura do feixe colimado foi avaliado (2 a 7 mm) para também quantificar o erro associado no cálculo da escala. O estudo foi realizado com simulação computacional, utilizando o código MCNP-X e validado por meio de equações analíticas que indicam a possibilidade de utilização deste estudo para este fim.

Thiago de Medeiros Silveira Silva, Aneuri Souza de Amorim, Mario Cesar Viegas Balthar et al.

The provision for the Brazilian Army of equipment that provides reliable and safe measurements, enabling decision-making based on radioprotection parameters, leads to the need to investigate the metrology of the calibration system used in the Radiation Monitor Calibration Laboratory (LabCal) of the Institute of Chemical, Biological, Radiological and Nuclear Defense (IDQBRN). To this end, the commissioning in cesium-137 is of primary importance in this process. In order to check the conformity of the radiator system, in this work, the ambient dose equivalent rate, , was obtained experimentally for several configurations to compare them with the appropriate theoretical concepts. For this, the distance between the source of Cesium-137 (36.9 GBq in 01/22/2015) and the ionization chamber was varied from 500 to 3000 mm at 250mm intervals. To obtain lower ambient dose equivalent rates, 15 and 32 mm thick lead attenuators were used. The mathematical model that best fit the experimental values was analyzed. In all cases, the potential function offers better fit, since the coefficients of determination obtained are approximately equal to 1, obeying the Law of the Inverse Square of the Distance, according to theoretical foundation. Moreover, it was evaluated that the relative deviations are below the limits established by the relevant standard.

Shomokh Alsharef, Mashael Alanazi, Fatimah Alharthi et al.

In the recent few decades, there was a growth in the field of radioactive medicinal agents called radiopharmaceuticals. Radiopharmaceuticals are consisting of radioactive materials called radioisotopes. Radiopharmaceuticals were recently used in both therapeutic and diagnostic purposes. More than 100 radioactive substances are used in nuclear medicine. According to the decay of radioactive substances, there are three types of radioactive decays, alpha particles, beta particles, and gamma radiations. Alpha particles consist of two protons and two neutrons with large mass and charge so it has no penetration power into the skin and has a destructive effect. Beta particles have less charge and less mass so, they can penetrate the tissue and have a less destructive effect than alpha particles and can be used in therapy. Gamma radiations have no mass or charge so they can penetrate the deep tissue of organs so used in diagnosis by imaging using a gamma camera. The radiopharmaceuticals were established in the diagnostic purpose and treatment of several diseases as thyroid gland cancer, hyperthyroidism, bone pain metastasis, kidney dysfunction, and myocardial and cerebral perfusion. The radioactive substance can also be used in the sterilization of thermo-labile substances as syringes, catheters, vitamins, hormones, and surgical dressing. The field of nuclear medicine has several advantages as localization of tumors, safe diagnosis, no accumulation of radiation, and high therapeutic efficacy. Nowadays, the branch of nuclear pharmacy is directed to introduce new radioactive pharmaceutical agents which will be important and effective in the treatment of cancer. The growth in the field of radiopharmaceuticals is important to help millions of patients suffering from tumors all over the world. The data of this review were collected by searching in Google Scholar and PubMed using the following keywords.

A. Pastorek, M. Ferus, V. Čuba et al.

Although the effect of ionising radiation on prebiotic chemistry is often overlooked, primordial natural radioactivity might have been an important source of energy for various chemical transformations. Estimates of the abundances of short-lived radionuclides on early Earth suggest that the primordial intensity of endogenous terrestrial radioactivity was up to 4x103 times higher than today. Therefore, we assume that chemical substances in contact with radioactive rocks should therefore undergo radiolysis. The calculations are followed by research investigating the influence of ionising gamma radiation on basic prebiotic substances, including formamide mixed with various clays, which might have played the role of a catalyst and an agent that partially blocked radiation that was potentially destructive for the products. Our explorations of this effect have shown that the irradiation of formamide-clay mixtures at doses of ~ 6 kGy produces significant amounts of urea (up to maximal concentration of approx. 250 mg∙l-1), which plays a role in HCN-based prebiotic chemistry.

I. V. Mednikov, V. V. Vasilyev, A. S. Busygin et al.

The article provides a brief description of organizational and technical measures aimed at ensuring radiation safety during the decommissioning of the heavy-water research nuclear reactor of Institute for Theoretical and Experimental Physics after A.I. Alikhanov of National Research Centre «Kurchatov Institute». Information is provided on the history and features of the operation of the reactor, including parameters and characteristics that are significant for planning and conducting work. The peculiarities of legal regulation in the field of ensuring radiation safety are given; regulatory acts and rules accompanying other activities during decommissioning and directly related to radiation safety are also considered. The paper describes the work done in preparation for dismantling, the initial and current state of the installation, forthcoming work with examples of dismantled equipment. Methods for handling radioactive waste arising during decommissioning are considered, including methods for fragmentation of large structural elements (examples of mechanical devices are given), methods for sorting according to different specific activity (high activity, low activity), radionuclide composition and physical properties (solid, metallic, non-metallic, liquid). A special method for handling liquid radioactive waste is described, which includes the collection and temporary storage system. To assess the radiation situation at workplaces during the dismantling of the reactor structures, calculations of radiation transfer were carried out on the running and shutdown reactor, during which it was established that the expected dose to the personnel when performing activities on decommissioning of TBR is much lower than the limit values, established by regulatory documents. In accordance with the estimated radiation doses, rules and instructions for personnel were determined, including the procedure for using personal protective equipment, the necessary measures for surface decontamination, etc. Information is given on the procedure for radiation monitoring at all stages of dismantling and at the final stages of decommissioning including control of premises, personnel, equipment, waste of various types, atmospheric air.

A. V. Akleyev, M. O. Degteva, L. Yu. Krestinina

The paper deals with the evaluation of the efficiency of the implemented protective measures in the event of accidental exposure of the Urals region population due to radioactive contamination of the Techa River and the 1957 accident. Both of the accidents occurred in one and the same region within approximately the same time frame, and were caused by discharges of Mayak Production Association radioactive waste into the Techa River (1949–1956) and into the atmosphere (1957). Counter-measures that had been undertaken to provide radiation safety of the population differed both in nature and in timeline. Their efficiency was insufficient in the Techa River basin as they were delayed in time and were not implemented to a full extent. But countermeasures in the East Urals Radioactive Trace were much more effective according to medical and dosimetric criteria. As a result, residents of the Techa riverside settlements received much higher organ doses, including doses to red bone marrow, and health effects of accidental exposure were registered in them both soon after and long after the radiation exposure.

V. G. Simonova, L. I. Bublikova

The article considers the radiation situation in the Oryol region 33 years after the accident at the Chernobyl nuclear power plant. Since 1998, certification has made it possible to assess the main indicators of the radiation situation in the region and conduct a comparative analysis, evaluate the doses of the population from all the main sources and the effects of the radiation factor on public health, and determine the most significant directions for reducing the doses of the population. The contribution of man-made sources to the collective dose to the population of the Oryol region in 2017 was 0.73% according to radiation-hygienic certification, which is 3 times higher than in Russia (0.24%). This is primarily due to radioactive contamination of a part of the region after the Chernobyl accident. The Oryol region is one of fourteen oblasts of the Russian Federation affected by the accident at the Chernobyl nuclear power plant. As a result of this disaster, 22 out of 24 districts of the Oryol Oblast (about 40% of the oblast’s territory) were exposed to radioactive contamination to one degree or another. Differences in precipitation led to the formation of extremely spotted pollution in the Oryol region. 1243 people from the Oryol region took part in the liquidation of the Chernobyl accident. 43% of them became disabled 1, 2 and 3 groups, 115 people (9%) died within 14 years after these events. In the Oryol region, the radiation environment remains stable. The radiation background is between 0.12 and 0.19iSv/h, which corresponds to the values characteristic of the Oryol region before the Chernobyl accident. Comparison of radiation doses due to additional radiation for the 1st and 33rd years after the accident showed a 51-fold decrease due to the physical decay of long-lived radioisotopes and short-lived radionuclides, as well as their burial in the soil.

Renato Koga de Avellar, Roberto Schirru

Application of Human Factors Engineering (HFE) in the design and implementation of such a project is essential to ensure that the new man-machine interface outcoming from the modernization does not have any negative impacts on human performance and plant safety. This paper analyzes the applicability of the Human Factors Engineering Program in the licensing and certification of Konvoi Nucleoelectric Power Plant Control Room modernization Project using digital instrumentation and control in accordance with U.S.NRC and KRA regulations. The results of the analyses show that although regulatory bodies adopt different methodology in the process of licensing the modernization of control rooms, the engineering aspects are being developed based on the principles of engineering.