Hasil untuk "Radioactivity and radioactive substances"

N. S. Aleksandrova

The Russian Federation Criminal Code provides for responsibility for stealing or extortion of nuclear materials and radioactive substances in order to ensure nuclear and radioactive safety and protection of especially dangerous objects from potential threats. The article presents an analysis of this crime taking into account the changes made to the current criminal legislation. The author considers the problems associated with the use of the analyzed crime and makes proposals for their legislative solution.

Gilles David Houndetoungan, Olatoundé Herbert Fachinan, Mahougnon Boniface Zinsou et al.

The objective of this study is to assess public exposure to natural background gamma radiation in Cotonou, southern Benin, in West Africa. This is a cross-sectional study with both descriptive and analytical aims, conducted from July to December 2024. The methodology involved continuous, georeferenced measurement of the ambient gamma dose rate at a height of one meter (1 m) above ground level using a spectrometer. The study sites included city streets and selected markets, including Dantokpa, an open-air market, and eight indoor markets. A total of 341,991 data points were recorded along the streets and 16,202 were recorded within the markets. The ambient gamma dose equivalent rate along the streets ranged from 4.67 to 136.84 nSv·h– 1, with an average of 25.11 ± 12.72 nSv·h– 1. The highest average rate was observed in District 5, which hosts a cement manufacturing plant. The average dose rates were 23.71 ± 12.90 nSv·h– 1 at the Dantokpa market and 69.72 ± 21.96 nSv·h– 1 in the indoor markets. In the latter, the dose rates were higher than those recorded in their respective districts. The estimated external annual effective doses were 0.04 ± 0.02 mSv for streets, 0.10 ± 0.06 mSv for Dantokpa, and 0.30 ± 0.09 mSv for indoor markets. These values remain below the worldwide average of 0.87 mSv, as recognized by the United Nations Scientific Committee on the Effects of Atomic Radiation for public exposure to natural radiation of terrestrial and cosmic origin. Overall, ambient gamma radiation exposure in Cotonou is low, though higher in enclosed market environments. These values may serve as baseline references for future studies in Cotonou and other African cities.

Christopher Rääf, Johan Martinsson, Mats Eriksson et al.

S. Petrov, S. Bondarenko, Masato Homma

The object of research is a new, potentially effective and practical process for the decontamination of radioactive soil, based on combination of plasma hydroseparation and plasma activation. The cleaning effect is ensured by the destruction of the bonds of radionuclides with soil particles due to a series of electrophysical discharges at which active particles and shock waves appear. In a designed setup, the process of plasma-chemical treatment is implemented in a plasma cell with a self-sustaining pulsating mode of burning an electric discharge, which occurs in an aqueous solution. The setup realizes a resonant increase in the intensity of shock waves, turbulence and multiple expansion of the core, such that the expansion of the plasma-liquid interface becomes a real basis for scaling up the setup. Regardless of the material of the electrodes and in a wide range of electrical conductivity (measured from 100 to 5,000 μS/cm), the restructuring of the combustion regime is accompanied by an increase in the size and stabilization of the luminous zone, fragmentation of bubbles, and an increase in the rate of their evacuation from the discharge zone. The main factors of such a restructuring are the channel dimensions and temperature of the solution. Various materials of the walls of plasma-chemical reactor have been tested: plexiglass, ceramics and stainless steel with the thickness of 2 mm. The maximum increase in the amplitude of resonance oscillations depends on the cell radius. A dynamic pressure, which in an individual discharge is about 5–15 mm of the water column at the mouth of the discharge, increases to 150–200 mm of the water column at the bottom of the plasma cell at resonance. An increase in efficiency is achieved by an optimal choice of the duration of the current phase and the distance between the electrodes, which is 15–30 mm. The voltage drop is 70–80 % across the spark discharge, the rest falls across the solution. The transition of the discharge to a periodic pulsating current mode with an increase in the temperature of the solution has been found. Tests on a mobile plasma-chemical facility for the process of plasma co-precipitation of radionuclides 137Cs, 134Cs and 90Sr with ferrocyanide sorbents under real conditions of hydroseparation of contaminated soil from fields around the Fukushima Daiichi have shown a decrease in organic substances in water by 40 times, and of radioactivity by 75 times.

G. de With, R. Bezhenar, V. Maderich et al.

Qi Sun, W. Peng, Suyuan Yu et al.

Abstract Graphite dust is the important contents of source term for safety analysis of high temperature gas-cooled reactors (HTGR). The spherical fuel element circulation in a pebble bed reactor causes many interactions between the fuel elements and other graphite components that inevitably leads to graphite dust production. Micron size graphite particles then move with the helium gas and deposit on various surfaces and in flow dead zones in the primary loop, which complicates equipment maintenance and repair and affects the heat transfer. In addition, the graphite dust is quite porous, so some radioactive fission products will adhere to the dust, which leads to radioactive fission products being distributed on the surfaces of the primary loop. Graphite dust carrying radioactive fission products can also leak into the environment during break accidents leading to radioactive pollution of the environment. Thus, studies are needed for the graphite dust transport in HTGRs. This paper reviews the research on the generation, distribution, radioactivity, deposition, resuspension and coagulation of graphite dust in a pebble bed high temperature reactor. The results show that most of the graphite dust is produced by mechanical wear, while chemical reactions can become an important source during an ingress accident. The graphite dust particles generally have sizes on the order of microns and carry radioactive substances. The graphite dust flows along with the helium in the primary loop and adheres to equipment surfaces. Local turbulent diffusion and large temperature gradients cause the graphite dust to deposit on the surfaces, while gravitational settling has a dominant effect in dead-end zones. In case of accidents or other transients, the dust deposited on the surfaces can become resuspended which will sharply increase the dust concentration, leading to uncertainties about the subsequent operating characteristics. In addition, coagulation and growth of the graphite dust particles due to thermophoresis and electric field forces is also a matter of concern.

Y. Sato, K. Minemoto, M. Nemoto

At the Fukushima Daiichi Nuclear Power Station (FDNPS) where an accident occurred due to a large tsunami caused by the Great East Japan Earthquake, understanding the distribution of radioactive substances is important to reduce the exposure dose to workers and establish decontamination plans. We focused on the importance of visualizing beta-emitting radiation sources in addition to gamma-emitting ones and proposed a method for three-dimensionally (3D) visualizing the location of beta-emitting radiation sources, which is important in discussing the effective dose for the crystalline lens of the eye. In this report, we have developed a technique to visualize the location of beta-emitting radiation sources in 3D by combining a directional Geiger-Mueller counter (G-M counter) with Structure from Motion (SfM). An image of 90Sr beta-ray source reconstructed using a beta-ray detector was projected onto a 3D model of the measurement area created using SfM, and the source location is identified in 3D. Additionally, we estimated the radioactivity of the visualized source. Then, by combining the beta-ray detector with a Compton camera, distinguishing between beta- and gamma-emitting radiation sources was possible. This study was based on the concept of integrated radiation imaging system (iRIS), which integrates multiple radiation detectors and environmental recognition devices.

Regiane Martins, Daniel Perez Vieira, Luma Ramirez de Carvalho et al.

Food irradiation proves to be an effective technique of eliminating some pathogens from food and this has gained significant attention to its potential for food safety. Since 1990, studies on the toxicological safety of 2-Alkylcyclobutanones have been conducted extensively. 2-Alkylcyclobutanones are unique radiolytic products generated by the radiation-induced breakage  of triglycerides in food, 2-dodecylcyclobutanone (2-dDCB) and 2-tetradecylcyclobutanone (2-tDCB) are the predominant compounds detected . Despite studies showing non-genotoxicity of 2-ACBs (2-Alkylcyclobutanones), the results are conflicting and therefore we continue the studies in order to confirm the compounds  are safety for human health. In vivo micronucleus test were performed to verify the 2-ACBs genotoxic effects in hepatic cells using flow citometry. We used cocoa butter irradiated with 20 kGy. A group with animals  was treated with daily intake of irradiated cocoa butter, synthesized 2-dDCB and 2-tDCB for one month. Hepatic cells were selected for genotoxicity analysis due to the liver importance in the compounds metabolization. The improvement of the analytical techniques is important for the research future since the irradiation process is already consolidated. The results confirmed the safety of the food irradiation process, as they did not indicate the genotoxic potential of the samples.   Keywords: 2- Alkylcyclobutanones, Micronucleous test, liver.

Richard Brandão Nogueira Vital, Jefferson Borges Araujo, Tatiane Melo Vital

The exchange of information between several business activities can lead to an increase in productivity and quality. In nuclear area, besides economic benefits, the operating experience exchanged can increase of the safety level of nuclear installations. Thus, it´s necessary to evaluate frequently operational occurrences from different countries and companies to learn with their lessons learned to prevent a recurrent events or unexpected consequences.  Because this, several methodologies are recommended to investigate events in an adequate level of depth and perform reports based on local requirements. Generally, these reports contain plant conditions before and after an event occurs (operation mode, operation limits and condition, date and time, nuclear and electrical power) and their information (failure discovery methods, impact to the safety, classification from INES and national regulation scale, similar events, relation to human factors, activation of emergency plan, recommended actions, root cause and causal factors). To allow the exchange of experience the Nuclear Energy Agency (NEA) and International Atomic Energy Agency (IAEA) maintain an Incident Reporting System (IRS) that permits interaction of several member states. In this system, a local coordinator collects information of the most relevant operating events and performs an evaluation of them based on IRS Guideline presented in an annual meeting. This paper evaluates a set of approximately four hundred events reported in IRS between 2014 and 2018. This evaluation has the objective of identify the most recurrent event root causes, operation mode and the effectiveness of corrective actions in course in the nuclear industry.

Marcelo Bessa Nisti, Marcelo Francis Máduar, Catia Heloisa Rosignoli Saueia et al.

This paper aims to propose an easy and fast method of optimization of the gamma-ray spectrometry counting time in determining natural radionuclides (Pb-210, Pb-212, Pb-214, Bi-212, Bi-214 and Ac-228) in order to minimize uncertainties in the concentration. The samples were measured by gamma-ray spectrometry with a hyper-pure germanium detector Canberra, 25% relative efficiency, effective resolution of 1.9 keV on the 1332.5 keV 60Co with associated electronics and coupled to a microcomputer. Multichannel Maestro A65-I model was used for spectrum acquisition and peak net area determination, and WinnerGamma/Interwinner 6.01 software was used for gamma-ray spectra analysis and to calculate the concentrations and associated uncertainties.  The counting times used were 86,000 s and 150,000 s.

T. B. Baltrukova

This article presents the review on the monograph “Scientific bases of radiation protection in modern medicine “volume 1” X-ray diagnostics “ by M.I. Balonov, V.Yu. Golikov, A.V. Vodovatov, L.A. Chipiga, I.A. Zvonova, S.A. Kalnitsky, S.S. Sarycheva, I.G. Shatsky, edited by Professor M.I. Balonov. – St.-Petersburg Institute of Radiation Hygiene after prof. P.V. Ramzaev, 2019. Due to the increasing use of ionizing radiation in medicine, implementation of new imaging modalities and equipment, increase of the patient and staff doses, the aspects of their radiation protection are very relevant. The monograph is based on the analysis of data from national and foreign studies, as well as the data from own research conducted in the laboratory of radiation hygiene of medical facilities of the St. Petersburg Research Institute of Radiation Hygiene named after Professor P. V. Ramzayev for almost 20 years. It reflects the current trends in radiation protection for various imaging modalities and it will be useful to a wide range of readers, especially specialists in the field of X-ray diagnostics and radiation hygiene.

Charalampos Doulgeris, Paul Humphreys

A. S. Samoilov, I. K. Romanovich, M. I. Grachev et al.

The article identifies areas of joint activities and mechanisms of interaction of Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing (Rospotrebnadzor) and Federal Medical and Biology Agency (FMBA of Russia), their territorial bodies and institutions in the event of radiation accidents. Extensive practical experience gained by specialists of FMBA of Russia and Rospotrebnadzor, was the basis for the development of the draft of Concept “Organization of radiation and hygienic measures in emergency situations of a radiation nature and coordination the activities of forces and means of FMBA of Russia and Rospotrebnadzor organizations and institutions” (2018). The article presents the main provisions of the draft document, which, after discussion and refinement, as the authors hope, this publication will contribute, draft of Concept can be submitted for approval. The modern infrastructure of Rospotrebnadzor and FMBA of Russia has all the necessary elements and prerequisites for coordinated work of expert support groups, use of the mobile specialized radiation-hygienic teams in emergency situations. The possible types of radiation accidents that may require joint activities of the bodies and institutions of Rospotrebnadzor and FMBA of Russia are considered. In the initial period of a radiation accident in conditions of large uncertainties related to the assessment of the radiation situation and doses on personnel and the public, it is necessary to ensure operative preparedness of consolidated proposals on making decisions on a complex of sanitary, hygienic, anti-epidemic and protective measures. Much attention is paid to mutual notification and information interaction. An important element in ensuring emergency preparedness, working out algorithms of the interaction of management bodies and practical skills of the personnel of Rospotrebnadzor and FMBA of Russia is the joint planning, organization and conduct of training and exercises.

Amanda Abati Aguiar, Danilo Faria, José Berretta et al.

Typical Pressurized Water Reactors (PWR) fuel rods are manufactured using zirconium-based alloys as cladding and slightly enriched UO2 sintered pellets as fuel. However, in the last years efforts have been made to develop Accident Tolerant Fuels (ATF) focusing mainly in new materials to replace the cladding in order to avoid the exothermic reaction with steam experienced by zirconium-based alloys under accident conditions as observed during the Fukushima Daiichi accident. In this sense, iron-based alloys appear as a possibility to replace conventional zirconium-based alloys, and the effect of the pellet geometry in the performance of iron-based alloys fuel rods shall be investigated. The fuel pellet geometry experiences changes due to irradiation can promote early gap closure, mechanical loadings to the cladding and/or bamboo effects due to the combination of loads and irradiation creep, and all these effects depend also on the cladding properties. The objective of this paper was to address the influence of geometric parameters in the fuel pellet behavior of a stainless steel fuel rod by means of structural mechanical analysis using the well-known ANSYS software. The parameters evaluated in this paper considered fuel pellet with and without chamfer and dish. The data related to the fuel pellet performance under irradiation were obtained using a modified version of the FRAPCON code considering stainless steel as cladding. Results obtained from mechanical evaluation considering the effects through the responses of the axial, radial, plastic deformations, and resulting tensions were evaluated.

Rafael Carvalho Barreto, Allan F. N. Perna, Danielle C. Narloch et al.

It was developed an improved theoretical model capable to estimate the radium concentration in building materials solely measuring the radon-222 concentration in a confined atmosphere. This non-destructive technique is not limited by the size of the samples, and it intrinsically includes back diffusion. The resulting equation provides the exact solution for the concentration of radon-222 as a function of time and distance in one dimension. The effective concentration of radium-226 is a fit parameter of this equation. In order to reduce its complexity, this equation was simplified considering two cases: low diffusion in the building material compared to the air, and a building material initially saturated with radon-222. These simplified versions of the exact one dimension solution were used to fit experimental data. Radon-222 concentration was continuously measured for twelve days with an AlphaGUARD detector, located at the Laboratory of Applied Nuclear Physics at Universidade Tecnologica Federal do Parana (UTFPR). This model was applied to two different materials: cement mortar and concrete, which results were respectively (15.7 +- 8.3) Bq/kg and (10.5 +- 2.4) Bq/kg for the radium-226 effective concentration. This estimation was confronted with the direct measurements of radium in the same materials (same sources) using gamma-ray spectrometry, fulfilled at Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), which results were respectively (13.81 +- 0.23) Bq/kg and (12.61 +- 0.22) Bq/kg.

Luciana Batista Nogueira, Jony Marques Geraldo, Cristiane Barsanelli et al.

The proposal of this study was to reproduce the dosimetry established by a treatment planning system (TPS) following a 3D conformational radiation therapy (3DCRT) protocol of two parallel-opposite fields applied to the left-breast in a thorax phantom, with the complementary use of the field-in-field technique. The computed tomography (CT) images of the thorax phantom were transferred to the XiO version-5 for the elaboration of the breast teletherapeutic planning with 2 Gy per day, in 25 fractions, with prescribed dose of 50 Gy. A set of ten EBT2 radiochromic films were irradiated at doses gradually. The values of RGB (Red, Green, Blue) of the films were obtained by scanning and data transformed in optical density (OD), whose values were used to construct the calibration curve. Radiochromic films were positioned outside and inside of the thorax phantom. After phantom radiation at the linear accelerator 6 MV Elekta Precise were measured the intensities of the films in RGB by software ImageJ, transformed in OD and converted in bidimensional dose distributions, applying the calibration curve. In addition, graphics and dose-volume histograms (DVH) were developed. The dose measurements in the glandular-TE in breast did not present statistically significant differences in relation to values at equivalent positions generated in the TPS. The organs at risk received doses below the reference values, according to TPS. It was possible to reproduce the dosimetry prescribed in TPS into the thorax phantom exposed to a breast conformational teletherapy. The use of the radiochromic films in dosimetry proves to be increasingly useful and shall become routine in radiotherapy services.

Bruno Quadros, Julia Silva Santiago Silveira Souza, Maria Gabriela Pedrozo et al.

O trabalho busca compreender o ponto de vista dos jovens estudantes do ensino médio sobre a geração de energia núcleo-elétrica no Brasil. Foi realizada uma pesquisa a partir de um questionário com alunos da Escola Sesc de Ensino Médio, indicativo de tal perspectiva. O entendimento, por sua vez, dá-se a partir da análise de influências educacional, social e familiar. Para melhor compreensão, divide-se os alunos em diferentes momentos do ensino médio, de acordo com o acesso que os mesmos tiveram a um conhecimento científico formal e informal. No estudo, nota-se que a aceitação acerca da geração de energia nuclear em território brasileiro ocorre de maneira gradual ao longo dos anos na escola.

Thiago César Oliveira, Roberto Pellacani Guedes Monteiro, Aluísio Souza Reis Júnior et al.

The zirconium isotope 93Zr is a long-lived pure β-particle-emitting radionuclide produced from 235U fission and from neutron activation of the stable isotope 92Zr and thus occurring as one of the radionuclides found in nuclear reactors. Due to its long half-life, 93Zr is one of the radionuclides of interest for the performance of assessment studies of waste storage or disposal. This paper describes the determination of 93Zr in evaporator concentrate (EC) sample from nuclear power plant (PWR). A zirconium selective separation using liquid-liquid extraction and TRU column were used before the ICPMS measurement to remove isobaric interferences.20-21 93Nb detection limit of 0.045 μg L-1 was obtained for 93Zr determination by ICPMS technique.

Ämilie Louize Degenhardt, Ana Letícia Dantas, Eder Augusto de Lucena et al.

The prompt response to emergency situations involving suspicion of intakes of radionuclides requires the use of simple and rapid methods of internal monitoring of the exposed individuals. The use of gamma cameras to estimate intakes and committed doses was investigated by the Centers for Disease Control and Preventions (CDC) of the USA in 2010.The present study aims to develop a calibration protocol for gamma cameras to be applied on internal monitoring based on urine samples to evaluate the incorporation of high-energy photon emitting radionuclides in emergency situations. A gamma camera available in a public hospital located in the city of Rio de Janeiro was calibrated using a standard liquid source of 152Eu supplied by the LNMRI of the IRD. “Efficiency vs Energy” curves at 2 and 10 cm were obtained. Calibration factors, Minimum Detectable Activities and Minimum Detectable Effective Doses of the gamma camera were calculated for 131I and 137Cs. The gamma camera evaluated in this work presents enough sensitivity to detect activities of such radionuclides at dose levels suitable to assess suspected accidental intakes.

Adam de Freitas Burgos, Leonardo Peres da Silva, Eduardo de Paiva

Atualmente, uma das alternativas ao tratamento radioterápico do fígado é a radioterapia estereotática corpórea (SBRT), que entrega altas doses em poucas frações, por conta do seu bom prognóstico. No entanto, para que se assegure que o alto valor de dose entregue ao alvo, seja o mesmo que o planejado, um teste de verificação de todo o processo (aquisição de imagens, delineamento, planejamento e a entrega da dose) deve ser realizado. Para isto, o objetivo deste trabalho foi desenvolver um simulador, com densidade de água, que leva em conta a posição relativa do fígado e dos órgãos de risco envolvidos neste tratamento, avaliando a influência da movimentação do alvo no valor da dose, em virtude do processo respiratório, assim como nas posições relativas aos órgãos de risco.