Hasil untuk "Radioactivity and radioactive substances"

Larissa Rocha Pitta Xavier, Luiz Antônio Mello, José Carlos C. Amorim et al.

Evaluating the nuclear material balance is an essential tool that can be used to assess the validity of the operator’s declarations of existing quantities of nuclear material from a facility, with an effect on safeguards agreements, where applicable. In summary, evaluating the nuclear material balance and associated safeguards activities enables the national regulatory authority to identify variations that may indicate deviations. A specific strategy used to detect potential deviations from assessing the material balance is known as "diversion into MUF", where MUF refers to the parameter Material Unaccounted For. It represents the difference between the book inventory and the ending physical inventory at the end of the material balance period. This evaluation is conducted through statistical analysis of the standard deviation of the MUF (σMUF) parameter, using an anonymous Brazilian facility as a case study. The ultimate goal is to implement this analysis within Brazil's control and accounting system, known as e-Gamma. This will enable the system to automatically perform such analyses for all facilities nationwide during each accounting period. This statistical study can be a powerful predictor of diversion, utilizing the σMUF parameter as a valuable resource. It is possible to suggest implementing this evaluation in control and accounting systems to increase efficiency in identifying and resolving discrepancies and anomalies, which is of fundamental importance in improving the reliability of a control system within the national scenario. Considering the international scenario, a country that increases its capacity to verify the accounting of nuclear material under its custody will tend to occupy a position of autonomy among its peers.

Susyleide G. Brito, Maria José A. Oliveira, Pablo Antonio Vásquez Salvador

The preservation of cultural assets, especially bibliographic collections, requires the dissemination of the gamma ionization technique, which is mainly used for the decontamination and sterilization of these materials. The procedure, which is used to preserve library collections in Brazil and other countries, is also used to preserve documents and art collections, being safe to handle, after ionization, once it leaves no residue behind. The aim of the study was to assess knowledge and identify behavioral aspects related to gamma ionization and its application in decontaminating collections. The target audience was a group of professionals who work with cultural assets in Pernambuco and other states. Two questionnaires were used, obtaining 39 and 105 respondents respectively, characterizing the participants and their knowledge of gamma ionization. The research was qualitative and quantitative, of a phenomenological nature. For the analysis, questions were grouped into thematic blocks, characterizing the participants, finding out “knowledge of gamma ionization itself” – with both knowledge and ignorance of the concept and application of the technique – and also collecting from participants their feelings, opinions and positions on various aspects of the application of gamma ionization. Finally, means and personal sources of obtaining information were specified, dealing with sharing of information.

Paulo Sérgio de Abreu Junior, Ricardo Felipe Soares, Thaís Soares Costa et al.

Galactic cosmic radiation (GCR) is the major risk in long-duration spaceflight when considering biological damage. Hence, monitoring the absorbed dose is required and biodosimetry will be considered an important tool especially in scenarios where physical dosimetry does not work. This integrative review tries to find, analyze, and compare different biodosimetric techniques capable of recording low doses of ionizing radiation (≤ 0.1 Gy) under simulation of spatial environments with respect to their operational applicability. The Aerospace Biodosimetric Performance Index is introduced to integrate the main parameters of the analysis. All results came from original articles in English available in open access published between 2019 and 2024 according to a PRISMA 2020 flowchart found in Scopus and PubMed databases and only eight studies were considered eligible for inclusion after performing a primary screening using Rayyan app. The major biodosimetric approaches recognized in the investigation are cytogenetic, molecular, and metabolic. The analysis time in the methodologies was between 2 and 70 hours, sample viability from 1 day to 2 years, and sensitivity as low as 0.05 Gy for the minimum detectable dose in some methods. The Yeast Metabolic Assay showed good applicability by combining high sensitivity with quick analysis and long viability. However, an absence of studies combining space radiation with microgravity constituted a major drawback. While many methodologies show detection capabilities at very low dose levels, few of them meet both the technical and operational requirements when considered together for prolonged space missions, hence a development challenge for hybridized yet more robust methods.

Tatjana Jevremovic, Haseeb ur Rehman

Guilherme S. Y. Giardini, Carlo R. da Cunha

This work demonstrates the application of a birth-death Markov process, inspired by radioactive decay, to capture the dynamics of innovation processes. Leveraging the Bass diffusion model, we derive a Gompertz-like function explaining the long-term innovation trends. The validity of our model is confirmed using citation data, Google trends, and a recurrent neural network, which also reveals short-term fluctuations. Further analysis through an automaton model suggests these fluctuations can arise from the inherent stochastic nature of the underlying physics.

Daria Boscolo, Giulio Lovatti, Olga Sokol et al.

Radioactive ion beams (RIB) are a key focus of current research in nuclear physics. Already long ago it was proposed that they could have applications in cancer therapy. In fact, while charged particle therapy is potentially the most effective radiotherapy technique available, it is highly susceptible to uncertainties in the beam range. RIB are well-suited for image-guided particle therapy, as isotopes that undergo \b{eta}+-decay can be precisely visualized using positron emission tomography (PET), enabling accurate real-time monitoring of the beam range. We successfully treated a mouse osteosarcoma using a radioactive 11C-ion beam. The tumor was located in the neck, in close proximity to the spinal cord, increasing the risk of radiation-induced myelopathy from even slight variations in the beam range caused by anatomical changes or incorrect calibration of the planning CT. We managed to completely control the tumor with the highest dose while minimizing toxicity. Low-grade neurological side effects were correlated to the positron activity measured in the spine. The biological washout of the activity from the tumor volume was dependent on the dose, indicating a potential component of vascular damage at high doses. This experiment marks the first instance of tumor treatment using RIB and paves the way for future clinical applications.

Steve Dye, Andrew Barna

We estimate the fluxes of heat and antineutrinos due to primordial radioactivity within the moon. We use a radial density profile, specifying an inner core and a model-averaged crust. Thickness, density, and elevation of the lunar crust are from remote measurements of the gravitational field. Lateral and vertical variations of thorium, uranium, and potassium abundances in the crust follow from a prediction of the lunar bulk chemical composition. We constrain the total contents of thorium, uranium, and potassium using estimates for the earth's primitive mantle. These contents produce $311\pm37$ GW of radiogenic heating and a surface-averaged heat flux of $8.19\pm0.97$ mW/m$^2$. Our lunar model estimates an antineutrino flux of $(1.83\pm0.32)\times10^6$ cm$^{-2}$s$^{-1}$ and an antineutrino inverse beta decay rate of $5.8\pm1.0$ per $10^{32}$ free proton targets per year, both averaged over the surface.

A. A. Faloppa, G. Fainer, C. D. R. Figueiredo et al.

The present report is a summary of the structural analysis of the pump nozzles applying the finite element method by using the Ansys computer program. The IEA-R1 RR is an open pool-type moderated and cooled by light water using beryllium/graphite as a reflector. The reactor can reach up to 5MW of thermal power cooled by the primary and secondary systems. The primary coolant system consists of a piping arrangement, a decay tank, two pumps, and two heat exchangers. The primary pump B1-B presented some failures requiring refurbishment by a new one. The pump used in the IEA-R1 must meet the requirements inherent to the nuclear installation, in addition to the operational requirements for rotating equipment, such as flow and pressure, and structural integrity of the body and nozzles. The supplier specified the type of pump suitable for the System. The pump furnished granted mechanical allowable loads for the nozzles that were lower than the loads imposed by the piping on the nozzles. To enable the installation of the pump in the primary circuit, new support was inserted in the piping system next to the pump minimizing efforts and deformations. A piping stress analysis was carried out to obtain the new efforts imposed on the nozzles. For validation of the motor pump set, a verification of the nozzles was done compared with API 610 standard loads, and the allowable loads of the provider. Finally, a structural analysis of the pump nozzles with the new loads was developed using the finite element method. The calculated stresses meet the limits prescribed by the ASME code; therefore, the new B1-B Pump is approved for operation at the IEA-R1 Nuclear Research Reactor primary circuit.

Yoshihiko Takase

The Fukushima nuclear disaster on March 11, 2011, has been reported to the IAEA and has been dealt with professionally. On the other hand, airborne monitoring was conducted in September 2011 for wide-area air dose rate surveys. As a result, Kashiwa City in Chiba Prefecture, which is about $200 \mathrm{km}$ away, was designated as an "intensive contamination survey area." Localized radioactive contaminations (hotspots) were often found and reported by residents there. The present study is a report of 2011 and 2012 dose rate measurements and 12 years of fixed-point monitoring at hotspots in Kashiwa City. A typical hotspot was a gutter and similar place where a large amount of rainwater was concentrated. The intensity distribution and time dependence of the dose rate at hotspots were measured. The dose rate over 12 years by fixed-point measurements agreed well with the sum of the radioactive decay characteristics of $^{131}\mathrm{I}$, $^{134}\mathrm{C_s}$, and $^{137}\mathrm{C_s}$. Decontamination in the living environment was conducted by sharing information between residents and the local government. It was effective to reduce the dose rate significantly by removing the sediment in the gutter and similar place. It is important to find hotspots in the living environments and decontaminate them intensively to reduce the risk of radiation injury to young children.

S. M. Andrievsky, S. A. Korotin, K. Werner

We have searched for lines of the radioactive element technetium (Tc) in the spectrum of Przybylski's star (HD101065). The nuclei of this chemical element are formed in the slow process of capturing thermalized neutrons. The possible lines of Tc~I are heavily blended. We have synthesized the profile of one resonance line at 4297.06 Å~, which is also a part of the complex blend, and we arrived at a decision that it is not visible in the spectrum (as was first noted by Ryabchikova), casting doubt on the existence of technetium in the atmosphere of the Przybylski's star. Therefore, based on our calculated combined profile, which has been adjusted to the observed blend profile at ~4297.2 A (that may possibly contain the resonance technetium line 4297.06 A), we reduce the maximum technetium abundance to $\logε$(Tc/H) = 2.5. This value can be considered only as an upper limit of the technetium abundance in the Przybylski's star.

Manuel García-León

Muhammad Farhan Ramadhany, Gede Sutresna Wijaya, Anung Muharini

Environmental radioactivity analysis has been carried out to determine the level of environmental radioactivity and the potential radiological hazards at Tanjung Enims coal mine. Gamma spectroscopy method has been carried out to identify radionuclides and their types of activity. The results of radionuclide concentration are used to determine the radiological hazard index and become input data for the Residual Radioactivity Onsite 7.2 application to determine the dose rate and long-term cancer potential received by workers in coal mines. The results obtained for the average concentration of radionuclide activity in coal samples are 226Ra, 232Th, and 40K are 72.468 Bq/kg, 86.905 Bq/kg, and 1802.049 Bq/kg, respectively. While the soil samples 226Ra, 232Th, and 40K respectively 79.205 Bq/kg, 100.209 Bq/kg, and 1443.275 Bq/kg. The radionuclide concentrations of both samples exceeded the UNSCEAR and worldwide reported averages for coal and soil. The average radiological hazard index for coal samples, namely Raeq, Hin, and Hex, was 335.500 Bq/kg, 1.102, 0.906, respectively. While the soil samples were 333.636 Bq/kg, 1.115, and 0.901, respectively. The index parameter is already lower than the UNSCEAR recommendation except for Hin, so there is a potential radiological hazard in internal pathways such as respiratory and digestive organs for mining workers. The total annual effective dose rate based on 5 RESRAD Onsite 7.2 pathways, namely external gamma, inhalation, radon, soil ingestion, and drinking water, is 1.675 mSv/year, exceeding the dose limits determined by ICRP, 1 mSv/year. The ELCR is 6.625*10^-3 which exceeds the UNSCEAR recommendation, 2.4*10^-4. Based on the results, it is necessary to intervene in the mining environment of the Tanjung Enims coal mine.

Gabriel De Lima Gonçalves, José Ubiratan Delgado, Fernando Barcellos Razuck

At the end of the nineteenth century, with the use of ionizing radiation for the benefit of humanity in various sectors of society, its effects on human health became evident. In this way, it is necessary to clarify the population about the main aspects related to the ionizing radiation applications, in order to better understand the concepts regarding their effects on health. And one of its main effects, within the area of radiological protection and medical physics, is called by Biological Effects. This is because ionizing radiations, due to their energy range, have the property of interacting with matter, and can alter the structure of cells by ionizing their atoms. Once it reaches the cells, ionizing radiation can produce damage, especially in DNA. This may occur either by the action of the radiation itself (direct mechanism) or by toxic radicals formed by the hydrolysis (indirect mechanism). These effects, over time, were identified and described, mainly from situations in which the man was acutely exposed (by accidents or medical use). In this sense, this paper proposes a bibliographic review of some concepts and definitions found in the literature on Biological Effects, mainly in Brazilian publications. With the purpose of not presenting a definitive theoretical model, but rather demonstrating the range of existing concepts, the objective of this paper is generating a debate about the variety aspects that may be related to the subject, reaffirming the importance of the topic for the area of radiation protection.

Leorlen Y. Rojas Mazaira, Carlos R. Garcia, Carlos Alberto Brayner Oliveira Lira et al.

In an iPWR (integral pressurized water reactor), the pressurizer is located at the top of the reactor vessel; this configuration requires the investigation of the mechanisms adopted for the homogenization of boron. In previous work, three representative experiments were conducted in an experimental installation made of stainless steel with a volumetric scale equal to 1:200, representing one-fourth of the pressurizer of an iPWR. The test facility layout was mounted so that the test section was fed with water or saline solutions with different concentrations, representing scenarios of boration or deboration. To determine the concentration at the inlet and outlet of the test section, samples have been collected every 10 min during the experiments representing some scenarios. The main goal in this work was to investigate how well mixing during boron dilution transients in the pressurizer of a small modular reactor can be modelled accurately by CFD (Computational Fluid Dynamics) codes. Two CFD codes were used, the commercial ANSYS CFX and the open source CFD code OpenFOAM. The use of open source software such as OpenFOAM offers a way to CFD gain acceptance in the licensing. The results of the comparison of simulations with an experiment at the test section were presented and showed a very good agreement. It was verified that deviations are less than 4%, both codes can be used to accurately represent this phenomenon. In order to improve future experiments, the dispersion of the solution inside the test section is studied with the aim to propose positions for sensors. A first simple configuration is proposed, but some further simulations will be done to find an optimum configuration.

Raysa Costa Nardes

In this work, the elemental composition of 21 coins from nineteenth and twenty centuries of South America belonging to a private collection were performed using the X-Ray Fluorescence (XRF). Different coin numismatic catalogs were used as reference material. The XRF measurements were performed using ARTAX 200 system (Bruker AXS Inc., Madison, WI, USA), which consists of an X-ray tube with Mo anode and a Silicon Drift Detector. The analyses were performed with a voltage and current of 40 kV and 600 μA, respectively, and an acquisition time of 100 s. It was possible to evaluate that all twenty-one pieces were made from metallic alloys. The major elements found were Fe, Cu, Ni, Zn and Sn. Twenty coins were consistent with their cataloged version, on the other hand, only one coin showed a different chemical composition from its cataloged version. So, this result can be an indication that this coin may be a fake.

G. G. Onischenko, A. Yu. Popova, I. K. Romanovich

35 years have passed since the Chernobyl NPP accident, 10 years – since the «Fukushima-1» NPP accident. At the present time extensive activities on the remediation of the consequences of two major large-scale radiation disasters are performed in the Belorussia, Russian Federation, Ukraine, and Japan. Releases of radiologically significant radionuclides after the Chernobyl NPP accident correspond to 14 exaBecquerel – higher up to an order of magnitude compared to 3 emergence power units of the «Fukushima-1» NPP. The significantly lower release rate and deposition of 80% of the radionuclides released into the atmosphere on the surface of the Pacific Ocean lead to lower up to several orders of magnitude radioactive contamination of the Japanese territory compared to the territories of the former USSR and neighboring countries after the Chernobyl NPP accident. Collective dose to the public due to the Chernobyl NPP accident is higher up to several orders of magnitude compared to the dose to the Japanese population after the «Fukushima-1» accident. No statistically reliable long-term medical consequences are expected for all groups of the Japanese public, additionally exposed due to «Fukushima-1» accident. 134 emergency workers have developed acute radiation sickness due to the Chernobyl NPP accident. Emergency workers with doses higher than 150 mSv had increased radiation-induced morbidity with leukemia and solid cancers. Among the individuals, that were kids or adolescents in the exposure period after the Chernobyl NPP accident and residing on the territories of Belorussia, Ukraine and four most radioactively contaminated regions of the Russian Federation, morbidity with thyroid cancer is increase by a factor of 10 compared to the pre-accidental levels. The following lessons of the Chernobyl NPP and «Fukushima-1» NPP can be derived: faults in the NPP design and lack of response after the recognition of the faults; lack of timely full-scale prophylactic with iodine; unjustified resettlement of the residents of the radioactively contaminated territories several years after the accident.

G. G. Onischenko, I. K. Romanovich, O. A. Istorik et al.

This paper is focused on the history of development and current state of regulation of the provision of radiation safety of the public. It includes data on the history of discovery of the X-rays, radioactivity and development of the atomic industry in the USSR and in the world as well as the issues of evaluation of the radiobiological effects of the ionizing radiation on the human and history of the development of regulations. It is indicated, that the principles of the radiation safety, norms and approaches to the provision of the radiation protection presented in the Federal state Law № 3-FZ “On the radiation safety of the public” and NRB 99/2009 fully comply with the ICRP Publication 60 (1990) and International Basic Safety Standard (IAEA, 1997). For decades, FZ-3 and NRB 99/2009 have allowed provisioning the high level of radiation safety of the personnel and the public.

Alan Souza Silva, Ricardo Carvalho Barros, Hermes Alves Filho

É apresentada neste artigo uma metodologia sintética analítica de solução da equação de transporte de nêutrons em geometria unidimensional utilizando a teoria .  A primeira parte da metodologia proposta neste trabalho consiste em obter uma solução analítica geral local para o sistema de equações  para um grau  ímpar arbitrário e grau de anisotropia de espalhamento .  Na segunda parte, a solução local analítica obtida para as equações  é utilizada como aproximante sintético nos termos integrais da fonte por espalhamento em uma versão simplificada da equação linear de transporte de Boltzmann [1]: estacionária, unidimensional, monoenergética, azimutalmente simétrica, em meios materiais não-multiplicativos e com fonte interior isotrópica.  A metodologia proposta foi implementada em um aplicativo computacional desenvolvido na plataforma  para Windows.  Além de gerar resultados numéricos para o fluxo escalar de nêutrons segundo o modelo , o aplicativo computacional gera resultados numéricos para os fluxos angulares de nêutrons em qualquer posição do domínio e para qualquer direção com projeção ortogonal sobre o segmento do domínio diferente de zero.  Para avaliar a aplicabilidade do método  e da proposta de solução sintética analítica da equação de transporte, são apresentados resultados numéricos para um problema-modelo característico.

F. Galtarossa, M. Pierens, M. Assié et al.

Direct nuclear reactions with radioactive ion beams represent an extremely powerful tool to extend the study of fundamental nuclear properties far from stability. These measurements require pure and dense targets to cope with the low beam intensities. The $^3$He cryogenic target HeCTOr has been designed to perform direct nuclear reactions in inverse kinematics. The high density of $^3$He scattering centers, of the order of 10$^{20}$ atoms/cm$^2$, makes it particularly suited for experiments where low-intensity radioactive beams are involved. The target was employed in a first in-beam experiment, where it was coupled to state-of-the-art gamma-ray and particle detectors. It showed excellent stability in gas temperature and density over time. Relevant experimental quantities, such as total target thickness, energy resolution and gamma-ray absorption, were determined through dedicated Geant4 simulations and found to be in good agreement with experimental data.