Hasil untuk "Radioactivity and radioactive substances"

W. C. Mei, S. J. Chen, X. F. Yang et al.

Molecules containing short-lived isotopes, namely radioactive molecules, are among the most promising candidates for probing new physics beyond the Standard Model, although their production and spectroscopic measurements remain technically challenging. Here, we demonstrate an integrated methodology that combines formation of molecular ion beams in a radiofrequency quadrupole cooler-buncher with collinear laser spectroscopy. As a proof-of-principle experiment, we successfully produce molecular ions such as $\rm BaF^+$ and $\rm YbF^+$ via in-trap ion-molecule reactions and perform high-resolution laser spectroscopy of the target molecule $\rm ^{138}BaF$. Vibrational and rotational structures of $\rm ^{138}BaF$ across different electronic states are obtained using resonance-enhanced multiphoton ionization schemes, confirming the feasibility of the proposed methodology. This work establishes a practical route for future formation and spectroscopic studies of short-lived radioactive molecules, such as those containing $\rm ^{225}Ra$, at radioactive ion beam facilities.

V. P. Ramzaev, V. S. Repin

In 1971 in the Perm region (the Russian Federation), three thermonuclear charges of the “Taiga” series were simultaneously detonated in order to test nuclear explosive technologies for creation of the Pechora-Kama canal. As a result of the underground explosions, long-lived technogenic radionuclides were released onto the surface of the earth along with soil and rock. Over time, a new forest ecosystem formed on the mound of the radioactively contaminated ground. The purpose of this study was to assess the 137Cs accumulation by woody plants and edible mushrooms at the “Taiga” underground nuclear explosions site at a remote stage (38 years) after radioactive contamination of the environment. Content of 137Cs was determined in organs of birch (Betula pubescens), spruce (Picea abies), aspen (Populus tremula), and pine (Pinus sylvestris), as well as in the fruiting bodies of mushrooms of the species Boletus edulis, Leccinum aurantiacum, Russula, and Suillus luteus. The activities of 137Cs in the samples were measured by gamma-ray spectrometry using a HPGe detector. The values of 137Cs activity concentration (on a dry weight basis) in the samples of wood, leaves/needles (1st year), and mushrooms were in the ranges of 0.5–6.8 Bq/kg, 54–112 Bq/kg, and 212-3260 Bq/kg, respectively. Aggregated transfer coefficients (kg/m2) for the radionuclide in the biota species were calculated using these results and previously reported data on the density of soil contamination by 137Cs at the “Taiga” site. It has been found that the transfer coefficients of 137Cs from soil to biota for all studied species at the “Taiga” site are abnormally low compared to those obtained by many authors for other places of radioactive contamination, in particular for the areas contaminated by 137Cs as a result of the Chernobyl accident. Possible reasons for the low accumulation of 137Cs in the biota at the “Taiga” site are discussed.

G. A. Gorsky, I. K. Romanovich

The pace of development of nuclear technologies is inextricably linked to the need to improve and update approaches to the preparedness of effective and adequate response to emergencies. The introduction of new solutions, which over the last few decades have significantly reduced the risks of severe consequences of major radiation accidents, cannot guarantee their absolute absence. Improvement of the systems of deep echelon radiation protection, radiation monitoring and control, the level of training of staff of radiation facilities cannot go separately from the development of a set of emergency preparedness and emergency response measures. The aim of the work is to review the systems of response to major radiation accidents recommended by ICRP and IAEA, and Russian federal laws and regulations. The results of the work have shown that when updating and revising sanitary norms and rules in the field of radiation safety, it is recommended to consider the need to supplement the current system of classification of radiation facilities by potential radiation hazard, with system criteria for categorisation of activities by the degree of emergency preparedness. These criteria would cover not only the operation of stationary radiation facilities for which a sanitary protection zone is established, but also operations with sources of ionising radiation outside stationary conditions, including transport of radioactive substances, operation of ships with nuclear propulsion systems, as well as radiation hazardous facilities located outside the country. The introduction of such categorisation creates a basis for determining emergency response zones and distances, which will make it possible to determine an effective set of radiation protection measures for the population planned by the authorities of the constituent entities of the Russian Federation together with the operating organisations and the authorities carrying out state regulation of safety in the field of the use of atomic energy.

Lysander Miller, Airlie Chapman, James Kennedy et al.

Advances in scintillation crystal and Silicon PhotoMultiplier (SiPM) technologies have enabled the development of compact, lightweight, and low-power radiation detectors that are suitable for integration with Unmanned Aerial Vehicles (UAVs). This integration enables efficient and cost-effective large-area radiation monitoring while minimising occupational exposure. In this work, a SiPM-based NaIL scintillation detection payload was developed, characterised, and mounted on a multirotor UAV for gamma ray and neutron source localisation and activity estimation applications. To support these capabilities, an analytic radionuclide detection efficiency model was developed and used to estimate radioactivity on the ground from aerial energy spectrum measurements. The analytic expression for the detection efficiency incorporated physical phenomena, including the branching ratio, detector solid angle, air attenuation, and intrinsic peak efficiency, leading to agreement within 10% of experimental radionuclide detection efficiencies. The UAV-based radiation detection system was physically validated through a controlled indoor live radioactive source demonstration at 1.5 m, 3 m, and 4.5 m flight heights. Using the developed ground-level radioactivity estimation method, Cs-137 and Co-60 sources were successfully localised within 0.5 m, and their activities were estimated with errors on the order of 10% or less.

Nikolai N. Chugai

Supernova 2018ibb of the PISN category related to the dynamical instability of oxygen core in a supermassive star induced by pair-creation shows at the nebular stage strong [\oiii] emission lines of an uncertain origin. I propose a simple model that demonstrates a possibility of [O III] lines emission from the supernova oxygen matter ionized and heated by the $^{56}$Co radioactive decay. The reason is pinpointed by which the [O III] line luminosity among supernovae of PISN category can vary in a broad range.

Moritz Pascal Reiter, Kriti Mahajan, Meetika Narang et al.

Molecules have proven to be sensitive tools for studying physics beyond the standard model, with heavy and deformed nuclei offering decisive sensitivity to parity- and time-reversal-violating effects. However, almost all elements beyond lead, occupying the 6p~to~5f atomic orbitals, lack stable isotopes, hence molecules containing them are referred to as radioactive molecules. Among those, radium monofluoride has seen particular interest, but to date, research on radioactive molecules has mainly been limited to large-scale nuclear facilities. Here, we present a scheme that allows efficient and fast harvest of radioactive ions (including short-lived Ra), and show ion gas-phase reaction studies of singly and doubly charged Ra, Po, and Pb ions with SF$_6$ gas inside an ion trap. Our results show that the chemical reaction rate of Ra$^+$ is in line with trends of other alkaline earth elements, further support by quantum chemical computations. The reaction Ra$^{2+}$ + SF$_6$ $\rightarrow$ RaF${^+}$ + SF$_5^{+}$ achieves an almost unity conversion efficiency, making it particularly suitable for the application for studies in physics beyond the standard model. The scheme enables future decentralized research avenues with short-lived radioactive molecules for fundamental physics research at laboratories without the need for local nuclear reactors or accelerators.

T. J. Roosendaal, C. T. Overman, G. S. Ortega et al.

The next generation of rare-event search experiments in nuclear and particle physics demand structural materials combining exceptional mechanical strength with ultra-low levels of radioactive contamination. This study evaluates chemical vapor deposition (CVD) nickel as a candidate structural material for such applications. Manufacturer-supplied CVD Ni grown on aluminum substrates underwent tensile testing before and after welding alongside standard Ni samples. CVD Ni exhibited a planar tensile strength of ~600 MPa, significantly surpassing standard nickel. However, welding and heat treatment were found to reduce the tensile strength to levels comparable to standard Ni, with observed porosity in the welds likely contributing to this reduction. Material assay via inductively coupled plasma mass spectrometry (ICP-MS) employing isotope-dilution produced measured bulk concentration of 232-Th, 238-U, and nat-K at the levels of ~70 ppq, <100 ppq, and ~900 ppt, respectively, which is the lowest reported in nickel. Surface-etch profiling uncovered higher concentrations of these contaminants extending ~10 micrometer beneath the surface, likely associated with the aluminum growth substrate. The results reported are compared to the one other well documented usage of CVD Ni in a low radioactive background physics research experiment and a discussion is provided on how the currently reported results may arise from changes in CVD fabrication or testing process. These results establish CVD Ni as a promising low-radioactivity structural material, while outlining the need for further development in welding and surface cleaning techniques to fully realize its potential in large-scale, low radioactive background rare-event search experiments.

Ana Carolina Delgado Vieira, Pablo Antonio Vasquez Salvador, Maria José Alves de Oliveira et al.

This article presents a case study on a ceramic vessel belonging to the Amazonian indigenous people, Asurini do Xingu, to investigate the use of gamma radiation for consolidating cultural heritage. Traditionally, gamma radiation is used to impregnate cultural artifacts with a radiocurable resin. In this study, the consolidating resin was applied only to the external surface of the vessel by brushing. The object was weighed before and after consolidation, and a colorimeter was used to evaluate possible color changes. The results indicated that the method was effective, with no negative effects on the appearance of the cultural item.

Victor Babiano-Suarez, Javier Balibrea-Correa, Ion Ladarescu et al.

Nuclear energy production is inherently tied to the management and disposal of radioactive waste. Enhancing classification and monitoring tools is therefore crucial, with significant socioeconomic implications. This paper reports on the applicability and performance of a high-efficiency, cost-effective and portable Compton camera for detecting and visualizing low- and medium-level radioactive waste from the decommissioning and regular operation of nuclear power plants. The results demonstrate the good performance of Compton imaging for this type of application, both in terms of image resolution and reduced measuring time. A technical readiness level of TRL7 has been thus achieved with this system prototype, as demonstrated with dedicated field measurements carried out at the radioactive-waste disposal plant of El Cabril (Spain) utilizing a pluarility of radioactive-waste drums from decomissioned nuclear power plants. The performance of the system has been enhanced by means of computer-vision techniques in combination with advanced Compton-image reconstruction algorithms based on Maximum-Likelihood Expectation Maximization. Finally, we also show the feasibility of 3D tomographic reconstruction from a series of relatively short measurements around the objects of interest. The potential of this imaging system to enhance nuclear waste management makes it a promising innovation for the nuclear industry.

R. D. Perevoshchikov, A. A. Perevoshchikova, E. A. Menshikova

This review provides information on the radiation situation in mining and energy production facilities. Mining activities are considered as one of the significant sources of radioactivity. Many radionuclides and metals that are transported by surface and ground waters, air flows over significant distances, contaminating soils, subsoil and bottom sediments of the adjacent territory, forming geochemically specific naturaltechnogenic areas. In this work is given an overview of radiation conditions in the territories of potassium phosphate, hydrocarbon and coal deposits. Developed potassium ores are the source of 40K emission into the environment. According to the results obtained, the migration of investigated radionuclides is limited to the zone of 2 km. Only an insignificant part of the investigated samples (8%) exceeds the world average activity of 40K for soils. In bottom sediments, the average activity of 40K does not exceed the values for other territories with anthropogenic impact. More than 30 million tonnes of phosphate fertilizers are consumed worldwide each year, and their use increases crop production. However, a possible negative effect of these fertilisers is the contamination of cultivated land with some natural radionuclides. Uranium concentrations in phosphate vary from 37 to 4900 Bq/kg for 238U and from 100 to 10 000 Bq/kg for 226Ra. The amount of radioactivity in oil, gas and formation water is estimated through determination of 40K, 226Ra, 232Th. According to the published data, increased radiation background is observed near wellheads, in the places of oil sludge accumulation, near the flares at oil and gas enterprises, as a result of bringing a number of natural and man-made radionuclides (226Ra, 232Th, 40K, 137Cs, 90Sr, etc.) to the day surface. Coal mines are sources of radioactive contamination. This results from the extraction of large amounts of natural radionuclides from the subsoil together with the coal. This paper presents the average natural radionuclides content in coals from some of the world’s coal mines. With the development of mining and fuel-energy complexes, there is an active export to the surface together with minerals of natural radionuclides 40K, 232Th, 226Ra, 238U, which leads to an increase in the radiation load on the environment. In this connection, the problems of ensuring radiation safety at the facilities of mining and fuel and energy industry require the closest attention.

Ricardo Andrade Terini, Johnatan Dias Oliveira, Elisabeth Mateus Yoshimura

Computed tomography (CT) images contribute to high-quality medical diagnosis, but radiation dose can be quite high, requiring accurate assessment. CT dose index (CTDI) was developed for dosimetric purposes, but for scanners operated exclusively in axial mode. Nowadays, CTDI underestimate patient dose in helical CT exams. AAPM report TG111 (2010) suggested a new metric in which the patient's radiation dose is obtained from dose profiles constructed from several measurements made with a small ionization chamber. It is also possible to obtain dose profiles using properly calibrated OSL (optically stimulated luminescence) strips. The main objective of the present work is to contribute to optimizing CT dosimetry, comparing dose profiles obtained with OSL strips with measurements obtained by other authors. In this work, a “pencil” ionization chamber and 20 cm x 0.3 cm OSL strips were X-ray-irradiated, in air and in the holes of two cylindrical CT phantoms, using 100, 120, 140 kV peak voltages, both in lab and in a clinical CT scanner. Irradiated strips were read using an OSL reader built in the GDRFM. OSL profiles were calibrated against ionization chamber. From them, CTDIw and CTDIvol values were determined, differing approximately 3.9% from those of the CT scanner. From the profiles, also the planar equilibrium dose Deq,p (TG111) was evaluated in some CT protocols; Deq,p exceeded the CTDI values from the CT scanner in every case. E.g.: The percentage difference between Deq,p and CTDIvol for the head phantom ranged between 33-25%. Thus, in some cases, it could be advantageous to use calibrated OSL dosimeters instead of ionization chambers to obtain the profiles, saving time, because it is possible to obtain five OSL profiles from a single phantom irradiation.

L. A. Chipiga, A. V. Vodovatov, A. A. Mosunov et al.

The aim of this study was to evaluate the activity of 225Ac in urine of patients undergoing radionuclide therapy with 225Ac-DOTA-TATE. Activity concentration was determined in the urine samples collected within 72 hours after injection of 225Ac-DOTA-TATE, using the ORTEC semiconductor gamma spectrometer, model TSP-DX-100T-PAC-PKG-1. Calculation of excreted activities was additionally performed based on scintig- raphy scans of patients receiving 225Ac-DOTA-TATE. Scans were conducted 5 times for each patient: immedi- ately after injection, at 4 hours, and on the 1st, 2nd, and 3rd days after injection of the radiopharmaceutical. Absolute activity values and fractions of the injected activity were calculated based on the specific activity values. The results of the calculated activity concentration values demonstrate that maximum excretion was observed within the four hours after 225Ac-DOTA-TATE injection. Significant differences between the two methods of determining 225Ac activity were observed only on the third day after radiopharmaceutical injection, which allows for the simplification of future experimental work by using indirect radioactivity measurement methods for activity calculations. There were no significant differences between patient groups with different number of 225Ac-DOTA-TATE injection, which allows for the exclusion of this parameter in the evaluation of experimental results. The results of this study represent the first published experimental data on the determi- nation of actinium excretion in patients.

M. Razab, N. Nawi, R. Sunaiwi et al.

Dealing with open sources of radioactive substances in nuclear medicine is a daily task since contamination due to radioactive spills may happen frequently. Proper and safe decontamination management is a vital procedure. However, regular purchase of decontamination agents incurs high costs and might be toxic due to their chemical properties. The purpose of this study is to compare graphene oxide, which is an environmentally friendly carbon-based material and marketable decontamination agent, in decontaminating radioactive spillage. Samples of pure 99mTc and 131I from the laboratory were spilled on a petri dish. The spill was immediately decontaminated with a marketable decontamination agent swab and varying concentrations of graphene oxide swab. The initial radioactivity of each swab containing 99mTc and 131I was measured using a dose calibrator. The absorbance spectra of each sample were analysed using an ultraviolet-visible spectrophotometer. The morphology image of graphene oxide was observed under field emission scanning electron microscope. For decontamination using a marketable decontamination agent, the radioactivity of 131I was slightly higher, whereas that of 99mTc was slightly lower than the high concentration of graphene oxide. The absorbance spectra of 99mTc and 131I that had been decontaminated using graphene oxide were observed at a range of 200 nm to 250 nm due ???* to the transition.

Ary de Araujo Rodrigues Junior

A computer program in PHP was developed to become easier the disposal calculus for radioactive material of low and medium radiation levels according to CNEN-801 (Low and medium radiation level waste management). The user selects some inputs as: the radionuclide name, its physical state, activity and obtains among others outputs:  the number of days for disposal and disposal date. There is an option for calculation without considering the radionuclide where the parameters are only the half-life, initial and disposal activity. It can be accessed by the Internet or downloaded from a repository to be installed on the users computer or server. The program language can be chosen between Portuguese and English.

Anna Cwanek, Mats Eriksson, Elis Holm

I. A. Zvonova, M. I. Balonov

A review of methods for assessing doses in the thyroid gland, predictions of the long-term consequences of its irradiation and the actual incidence of thyroid cancer in residents of four regions of the Russian Federation with the most significant radioactive fallout after the Chernobyl accident are presented. The method for assessing doses in the thyroid gland is based on the results of monitoring in May-June 1986 of radioiodine in the environment, food and in the body of residents. Thyroid doses in the population were used to justify medical and social protection measures, as well as epidemiological studies. In addition, the authorities needed forecasts of the possible morbidity of the population in order to organize adequate medical care. Most of the thyroid cancer cases were predicted among the adult population, which was not confirmed by observations 35 years after the accident. The prognosis of the incidence of thyroid cancer in preschool children differed in different studies due to the use of different coefficients of reducing the biological effectiveness of 131I radiation in the thyroid gland and long-term external and internal irradiation of the whole body with a low dose rate compared to the effect of acute exposure. The increase in the incidence of thyroid cancer among children began five years after the accident at the Chernobyl nuclear power plant. Examples of the dynamics of the incidence for children in the Bryansk region of the Russian Federation are given. The 2018 UNSCEAR Report showed that for 1986-2015, among children and adolescents under 18 years of age on the day of the accident in Belarus, Ukraine and four regions of Russia, more than 19 thousand thyroid cancer cases were detected, of which the share of radiation-induced diseases was estimated at 25%. For four regions of Russia, this amounts to 460 cases with a range of possible estimates from 130 to 900 cases. The highest morbidity was manifested among younger children exposed at the age of 0-4 years. In older children and adolescents, the proportion of radiation-induced diseases has significantly decreased 30 years after the accident. In general, early forecasts of radiation-induced thyroid cancer incidence in children in four regions of the Russian Federation with high levels of radioactive fallout are consistent with the data of subsequent 30-year epidemiological observations within an order of magnitude. With regard to thyroid cancer in adults, such a comparison is difficult, since no radiogenic increase in the incidence has been detected.

Nathalia Fonseca Boiani, Vanessa Silva Garcia Granadeiro, Sueli Ivone Borrely

There are serious evidences that justify the search for treatment technologies or processes combination for the improvement of decomposition for dozens of pharmaceuticals in wastewaters. Electron beam irradiation may play an important role in this scenario and relatively low doses have been reported for such purposes. The aim of the present study was to evaluate the toxic response of the crustacean Daphnia similis exposed to individual and combined pharmaceuticals, before and after electron beam irradiation treatment. Several experimental trials of an acute immobilization test were performed with a mixture of pharmaceuticals composed of fluoxetine hydrochloride (Prozac®), and propranolol. Single pharmaceuticals were first tested separately. Toxicity of binary mixture was then assessed using five concentrations and five percentages of each substance in the mixture (0, 25, 50, 75, and 100%). Acute EC50% values ranged from 5.0 to 7.4 for fluoxetine and from 11.3 to 13.7 for propranolol. In mixture, values ranged from 6.4 to 9.8. Fluoxetine was more toxic than propranolol for D.similis. The different pharmaceuticals concentrations employed in a mixture showed no difference in toxicity values. When electron beam irradiation was applied, approximately 80% of acute effects were reduced at 5 kGy, and the mixture containing a higher percentage of fluoxetine, also showed a greater reduction of toxicity.

I. I. Berezin, S. S. Somov, К. V. Yakusheva

The technical passport for the X-ray room in accordance with the current sanitary legislation is a mandatory document certifying the technical condition of X-ray diagnostic equipment, devices for developing, fixing and drying X-ray films, additional equipment and accessories for performing special types of X-ray diagnostics, means of protection against ionizing radiation of workplaces of the office staff and adjacent to the office of the premises and confirming the compliance of their characteristics with the normative and technical documentation and domestic standards. The purpose of this work was to assess the relevance and necessity of issuing a technical passport for the X-ray room and to coordinate the project of the X-ray room with the X-ray department in the light of the current sanitary legislation. Registration of a technical passport by organizations that have special permits for these types of work, and not only by the X-ray and radiological department, would increase the legal value of the technical passport. The information contained in the technical passport is duplicated in the rest of the documentation for the X-ray room, the requirements for which are enshrined in the sanitary legislation, which generally casts doubt on the need for a technical passport as a mandatory document.

G. Baccolo, A. Barresi, M. Beretta et al.

In the framework of rare event searches, the identification of radioactive contaminants in ultra-pure samples is a challenging task, because the signal is often at the same level of the instrumental background. This is a rather common situation for $α$-spectrometers and other detectors used for low-activity measurements. In order to obtain the target sensitivity without extending the data taking live-time, analysis strategies that highlight the presence of the signal sought should be developed. In this paper, we show how to improve the contaminant tagging capability relying on the time-correlation of radioactive decay sequences. We validate the proposed technique by measuring the impurity level of both contaminated and ultra-pure copper samples, demonstrating the potential of this analysis tool in disentangling different background sources and providing an effective way to mitigate their impact in rare event searches.

Katashi Kubo, Hiroyuki Kobayashi, Miyuki Nitta et al.

AbstractDecreasing the transfer of radioactive cesium (RCs) from soil to crops has been important since the deposition of RCs in agricultural soil owing to the Fukushima nuclear power plant accident of 2011. We investigated the genotypic variation in RCs accumulation in 234 and 198 hexaploid wheat (Triticum spp.) varieties in an affected field in 2012 and 2013, respectively. The effects of soil exchangeable potassium (ExK) content to RCs accumulation in wheat varieties were also evaluated. A test field showed fourfold differences in soil ExK contents based on location, and the wheat varieties grown in areas with lower soil ExK contents tended to have higher grain RCs concentrations. RCs concentrations of shoots, when corrected by the soil ExK content, were positively significantly correlated between years, and RCs concentrations of shoots were significantly correlated with the grain RCs concentration corrected by the soil ExK content. These results indicated that there were genotypic variations in RCs accumulation. The grain to shoot ratio of RCs also showed significant genotypic variation. Wheat varieties with low RCs accumulations were identified. They could contribute to the research and breeding of low RCs accumulating wheat and to agricultural production in the area affected by RCs deposition.