Hasil untuk "Radioactivity and radioactive substances"

Ione Makiko Yamazaki, Denise Simoes Moreira, Mauro da Silva Dias et al.

The Nuclear Metrology Laboratory (LMN) at IPEN-CNEN/SP is developing a research project aimed at studying analytical techniques for determining radioactive impurities, emitting alpha and beta particles. This project started with the determination of impurities present in 99Mo, which is used to obtain the radiopharmaceutical 99mTc by means of radiochemical separation in the 99Mo/99mTc generator.  The study of the anionic extracting agent Strata X-A widely used in quality analysis, was realized by means a breakthrough curve in order to validate its total exchange capacity for Mo. The breaking point was determined at (2.75 +/- 0.14) mL, showing that just one 0.5 g Strata X-A cartridge is sufficient to retain 1.0 mL of a (Na2MoO4+ 99Mo) solution in concentration of 2.42 g L- 1.

Angélica Barbezan, Wilmmer Alexander Rosero, Luis Fernando Almeida et al.

This study evaluated the biodistribution of gum arabic-functionalized gold nanoparticles (GA-AuNPs) in Balb/C Nude mice following intravenous administration. Two activity regimens (200 µCi and 600 µCi) were analyzed at two different time points (3 and 24 hours post-injection). The results showed predominant accumulation of GA-AuNPs in the liver, spleen, and gallbladder, suggesting hepatobiliary excretion as the primary clearance route. A reduction in liver uptake after 24 hours indicates potential nanoparticle metabolism or elimination. Although this study focused on intravenous delivery, previous work from our group using BSA-coated AuNPs administered intratumorally demonstrated higher tumor retention and reduced systemic accumulation, reinforcing the importance of administration route and surface coating in defining nanoparticle biodistribution. These findings contribute to the understanding of how delivery strategy influences nanoparticle bioavailability and support the development of safer and more targeted therapeutic platforms.

Francky Roger Araujo da Silva, Giovanni Laranjo de Stefani, Marcelo Vilela da Silva

This article analyzes the SWOT Matrix for the implementation of the AP-Th1000 reactor with thorium fuel, aiming at a future replacement of the current nuclear reactors that use uranium as fuel by thorium. There was a need for an in-depth study of the national and international literature linked to the Brazilian reality. After that, specific meetings were held to detect all possible situations of the 4 main points of the SWOT matrix. During the sessions, which averaged 1 hour, the authors' industrial and academic expertise was demonstrated in competencies such as creativity, collaboration, effective communication, openness and tolerance, quick thinking, synthesis ability, problem focus, and flexibility during the discussions of over 50 items found in the analysis of the 4 points of the SWOT matrix. Each meeting was divided into three parts. The first part, which would be the Creative phase; and a second part, which would be the Critical phase; and, finally, the third phase, where ideas are filtered for the permanence of those that were better founded and of better acceptance. Then, the aspects listed were classified into 4 categories: Strengths (S), Weaknesses (W), Opportunities (O), and Threats (T). After the classification, a ranking of priorities was made, in descending order of importance, according to the authors, of the weaknesses and threats, neutralization suggestions were made. Finally, the data obtained were analyzed. We concluded through the SWOT analysis, we can observe an expressive amount of benefits of using the AP1000 reactor with MOX of Thorium and Uranium in the development of nuclear energy generation technologies in Brazil.

N. U. Khakimova, M. A. Zoitova

The article provides an overview of the problems associated with the uranium tailings in Istiqlol city. Many uranium heritage sites in Central Asia, including the uranium tailings in Istiqlol, hadn’t been mothballed before the collapse of the USSR. The burial complex consists of a quarry, dumps of the “Poor Ores Factory”, an unpreserved open mine, destroyed industrial buildings and four tailings which contain 12 million tons of the uranium production waste. In the area of the tailings, the ambient dose rate of gamma radiation is 0.5–0.6 μSv/h, and at some points it reaches 3.0–4.0 μSv/h. The average annual radon emission from the surface is estimated at 3.9×1011 Bq/year. The contaminated areas also include the Sarym-Sakhly Sai stream, mine, industrial and quarry waters, which are characterized by an increased content of 234U, 238U and 226Ra. The facilities aren’t physically fenced, allowing free access for the public and livestock. Natural disasters such as mudflows, landslides, and earthquakes can lead to an ecological disaster. Attention is paid to the ways of solving problems such as monitoring radionuclides in water, soil, and air; working with the local population to inform and involve them in rehabilitation work; donors search. The Program for the Implementation of the National Concept for the Rehabilitation of Tailings of Uranium Ore Processing Wastes for 2016–2024 was developed and approved by the Government of the Republic of Tajikistan to minimize the radiation impact on the population and the environment. Implementation of the Program requires significant financial investments and trained personals in the field of radiation safety. Only through the joint efforts of the state, population and international organizations is it possible to fully carry out rehabilitation works. Only by joint the state, public, and international organizations efforts, it is possible to solve these problems. Also, one of the main reasons why the population had received unnecessary overexposure was its ignorance of the danger of using water, soil and building materials contaminated with radionuclides. Therefore, the culture of radiation safety should be studied starting from middle school, where students will be taught about ionizing radiation and possible ways of exposure. Then, both cases of intake of radionuclides into the body, which could have been avoided, and radiophobia among the population living near the extraction and processing of uranium ore, will be much lower. Some social and economic aspects are also touched upon.

Pedro Henrique Silva Rodrigues, José Rubens Maiorino, Roberto Asano Júnior

This work presents the description of the first part of a methodology applied to perform In-Core Fuel Management (ICFM) in Pressurized Water Reactor (PWR). The ICFM of a PWR reactor consists on defining the best charging or recharging pattern of fuel assemblies inside a reactor for an operational cycle. This means, finding a suitable arrangement of fuel assemblies that optimizes the performance of the reactor, which complies with all safety criteria. Genetic algorithms (GAs) are used to select the arrangements that interact with the reactor physics simulation code, holding the neutron characteristics of each fuel assembly. Therefore, a reliable and fast code was developed accordingly. The consolidated technique of coarse mesh node code that numerically solves the multigroup diffusion equation for two groups of energy, fast and thermal neutrons, in two dimensions was selected. In this type of code, it is essential that each fuel assembly is homogenized and characterized by its macroscopic cross sections, for each reactor’s burnup condition. The cross sections are generated with the support of SCALE 6.0, computational platform developed by the Reactor and Nuclear Systems Division (RNSD), from the Oak Ridge National Laboratory (ORNL). The completeness of the qualification and validation of the results obtained from the homogenization of the fuel assembly by the SCALE was performed comparing the results with actual data of a benchmark reactor. The fully documented Almaraz Nuclear Power Plant provided by the International Atomic Energy Agency (IAEA)-TECDOC-815, has been used as benchmark with successful results.

article Editorial

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Guilherme Costa de Oliveira

This work aims optimized to set up and an analytical method for a reliable determination of silver-indium-cadmium alloy constituents and their impurities through the use of ICP OES (Inductively coupled plasma optical emission spectrometer). It has greater precision, accuracy, and sensitivity when compared to the traditional methodology. The validation process was carried out according to INMETRO’s (Instituto Nacional de Metrologia, Qualidade e Tecnologia) Analytical Method Validation Guidance.

Tiago Augusto Santiago Vieira, Rebeca Cabral Gonçalves, Izabella Cristina de Paiva Machado et al.

In this work, a single step of coupled calculations for a fuel rod of IPR-R1 TRIGA was performed. The used me-thodology allowed to simulate the fuel pin behavior in steady-state mode for different power levels. The aim of this paper is to present a practical approach to perform coupled calculations between neutronic (Monte Carlo) and thermal-hydraulic (CFD) codes. For this purpose, is necessary to evaluate the influence of the water thermal-physical properties temperature variations on keff parameter. Besides that, Serpent Nuclear Code was used for the neutronics evaluation, while OpenFOAM was used for thermal-hydraulics. OpenFOAM si- mula-tions were made by using a modified chtMultiRegionFoam solver, developed to read Serpent output correctly. The neutronic code was used without any modifications. The results shows that this coupled calculations were consistent and that leads to encouraging further methodology development and its use for full core simulation. Also, the results shows good agreement with calculations performed using other version of OpenFOAM and Milonga as neutronic code.

Ellison Amaro de Oliveira, Patricia da Silva Pagetti de Oliveira, Miguel Mattar Neto et al.

Deterministic and probabilistic nuclear safety analysis methodologies have been developed and updated based on operational experience, investigation of past incidents or accidents, and analysis of postulated initiating events in order to maintain the protection of workers, the public and the environment. The evaluation of accident sequences and the total radiological risk resulting from off-site releases are general objectives addressed by these methodologies. There are hazards that continually challenge the safety of a nuclear facility or its nearby area. In particular, seismic events represent a major contributor to the risk of a nuclear facility. Different levels of ground motion induced by earthquakes may be experienced by the structures, systems and components (SSCs) of the installation. In this context, a seismic hazard analysis, seismic demand analysis and seismic fragility analysis must be carried out in order to characterize the local seismic hazard and what are the seismic demands on SSCs, allowing an adequate seismic classification of SSCs, even in installations located in sites with low seismicity. In this article, a general description of the Seismic Probabilistic Safety Assessment (Seismic PSA) methodology is presented, with emphasis on their support studies, aiming at applying the methodology described in this article to an experimental nuclear installation containing a PWR reactor designed for naval propulsion to be installed in a low seismicity zone in Brazil.

André de Souza Bezerra, Carlos Alberto Zeituni, Maria Elisa Chuery Martins Rostelato

Observation and identification of predictive factors for results and morbidity are essential in the ideal selection of patients who can use brachytherapy as a treatment modality for prostate cancer. Thus, the objective of this research is to analyze the population of patients with prostate cancer treated at the General Public Hospital of Palmas in 2015, in the state of Tocantins. The method used was quantitative, with the characteristics of a retrospective, transversal and descriptive analysis. Held in the largest state health unit, the General Public Hospital of Palmas that, despite its large dimensions, lives with the main problems of the Unified Health System, such as overcrowding and shortages. It was found that most of the patients seen corresponded to the age of 70 to 79 years, making 45%, followed by patients aged between 60 and 69 years, with 33%. Most of the individuals attended were from the state of Tocantins, but some lived in an adjacent city in the state of Pará. Data related to the Gleason score showed that there was a predominance of levels 6 and 7 indicating intermediate grade tumors, considering that the most of the observed population was older. It was concluded that the analyzed patients had a predominant staging of CaP II and III, thus most of the individuals, 23 of the 35 analyzed, were not able to undergo brachytherapy due to the high degree of disease staging.

Aluisio Souza Reis, Roberto Pellacani Guedes Monteiro

This work refers to determination of thorium and uranium isotopes in the mining lixiviation liquor samples. The analytical procedure involves sample preparation steps for rare earth elements, thorium and uranium separation, besides alpha spectrometry analysis of the isolated radionuclides. An isotopic tracer is used to determine the overall chemical yield and to ensure traceability to a standard sample from NIST. The paper presents and discusses that the chemical yield of thorium and uranium depends on the leaching method used, that is, column leaching or agitated leaching. We improved the method looking for reproducibility and isotopes isolation as required by alpha spectrometry and the method showing effective in analysis of mining liquor

Claubia Pereira, Jéssica P. Achilles, Fabiano Cardoso et al.

A spent fuel pool of a typical Pressurized Water Reactor (PWR) was evaluated for criticality studies when it uses reprocessed fuels. PWR nuclear fuel assemblies with four types of fuels were considered: standard PWR fuel, MOX fuel, thorium-uranium fuel and reprocessed transuranic fuel spiked with thorium. The MOX and UO2 benchmark model was evaluated using SCALE 6.0 code with KENO-V transport code and then, adopted as a reference for other fuels compositions. The four fuel assemblies were submitted to irradiation at normal operation conditions. The burnup calculations were obtained using the TRITON sequence in the SCALE 6.0 code package. The fuel assemblies modeled use a benchmark 17x17 PWR fuel assembly dimensions. After irradiation, the fuels were inserted in the pool. The criticality safety limits were performed using the KENO-V transport code in the CSAS5 sequence. It was shown that mixing a quarter of reprocessed fuel withUO2 fuel in the pool, it would not need to be resized

Lais Alencar de Aguiar, Arlene Alves dos Reis, Raul dos Santos

The IAEA publication EPR-NPP-OILs-2017, OPERATIONAL INTERVENTION LEVELS FOR REACTOR EMERGENCIES AND METHODOLOGY FOR THEIR DERIVATION [1], provides selected default OIL values, describing a methodology for their derivation, as well as practical tools and recommendations for their use. IAEA recommends that tools and default OIL values be directly integrated into national emergency arrangements or reviewed and modified as necessary to meet the specific emergency preparedness and response arrangements. The Institute of Radiation Protection and Dosimetry (IRD) has a Radiological Assessment TEAM (EAR) as part of its Radiation Emergency Response System. Brazilian regulatory standards address actions for radiation emergencies encompassing necessary measures to assess public exposures, intervention levels to protect the public and recommendations for protective actions as, evacuation, relocation, sheltering and food restrictions. The objective of this paper is to present a discussion the use  these OILs, to compare those ones established by the Brazilian standards and to propose a methodology on  how OILs can be used by EAR/IRD  in case of an emergency at the Brazilian NPP.

Ana Letícia Almeida Dantas, Mylena Queiroz Saraiva, Eder Augusto Lucena et al.

123I is a radionuclide used for diagnosis in nuclear medicine. Its production in Radiopharmacy Centers poses a risk of external and internal exposure to the workers involved in this practice. Controlling this type of exposure through individual monitoring is necessary to estimate the magnitude of occupational doses. The In Vivo Monitoring Laboratory (LABMIV-IRD) develops techniques aimed at meeting the demand for in vivo monitoring of workers. This paper describes the calibration of a HPGe detection system for monitoring 123I in thyroid geometry in occupationally exposed individuals (OEI). In order to obtain the calibration curve in Efficiency (cps/dps) vs Energy (keV), it is used a thyroid-neck phantom containing a certified activity of 166mHo homogeneously distributed. Based on the calibration curve it is calculated the specific calibration factor for the quantification of 123I in the thyroid. The sensitivity of the technique is evaluated by determining the minimum detectable activity (MDA), minimum detectable intake (MDI) and minimum detectable effective dose (MDED). It was obtained a calibration factor of (0.0079 ± 0.0001) cps/dps, a MDA of 5Bq, a MDI of 2.78x106 Bq and a MDED of 3.23x10-1 mSv. The technique is sufficiently sensitive for in vivo measurement of 123I in the thyroid and is suitable for the monitoring of workers occupationally exposed to this radionuclide in  radiopharmaceutical production plants.

Tallyson Sarmento Alvarenga, Claudio Antonio Federico, Caio Cesar Valeriano et al.

Com o aumento do uso de técnicas que utilizam radiação de nêutrons, houve um crescimento considerável no número de detectores para esse tipo de radiação. Foi projetado um laboratório de calibração de detectores com nêutrons (241AmBe). Nas situações práticas neste tipo de laboratório, um dos problemas principais está relacionado ao conhecimento da radiação espalhada. Com o intuito de avaliar esta radiação espalhada, foram realizadas simulações sem a presença dos elementos estruturais e com a sala completa. Foram avaliados quatorze pontos de medições em direções diferentes a várias distâncias.

I. K. Romanovich, G. Ya. Bruk, A. N. Barkovskiy et al.

The article contains substantiation of criteria of return of territories with radioactive pollution caused by Chernobyl NPP accident to conditions of normal population activity. It is established that in 12 entities of the Russian Federation (except Bryansk and Kaluga regions) all agricultural food produce, including that from the personal part-time farms, corresponds to hygienic specifications. Non- corresponding to the standard SanPiN 2.3.2.1078-01 on 137Cs are part of the milk samples produced at personal part-time farms of the Bryansk region and most of natural foodstuff samples (berries, mushrooms, fish and wild animals meat) in Bryansk and Kaluga regions. The content of 137Cs both in agricultural and in wild-growing foodstuff produced at radioactively contaminated territories depends not only on the density of radioactive pollution, but also on the types of soil. The average settlement annual effective dose of population irradiation (AAED90) in the 3700 among 4413 settlements as of 2014 was below 0.3 mSv/year. Only in 713 settlements of Bryansk, Kaluga, Oryol and Tula regions the AAED90 exceeds 0.3 mSv/year. In the Bryansk region, once subject to the greatest radioactive contamination, in 276 settlements AAED90 exceeds 1 mSv/year, and in 8 of them - 5 mSv/year.The legislation of the Russian Federation defines only criteria and requirements for consideration of the suffered territories as zones of radioactive contamination. Requirements on transfer of territories polluted by radiation accidents and their population to normal life activity conditions (regarding the radiological factor) are not developed.Radiological criteria are suggested for transfer of the settlements considered to be the zone of radioactive pollution to conditions of normal life activity: average irradiation dose of critical population group: 1.0 mSv per year and lower (AAED crit); decrease of radionuclide soil contamination density to the level enabling to use the territory for traditional agricultural production meeting sanitary requirements without special measures for decrease of the 137Cs or other radionuclides content.

D. V. Kononenko

The paper presents the results of risk assessment from exposure to radon before and after radon mitigation actions in school. Twofold reduction of radon EEC (from 231 to 109.6 Bq/m3) in the long term can lead to decrease of lifetime attributable risk by 2.2–2.4% for the entire population (depending on the standard population used), 2.7% for men, 1.2% for women. These results were obtained using «FCZ» model. Models «EPA-2003» and «Wismut-2006» were not sensitive enough for use in such tasks.

V. P. Ramzaev, A. V. Sevast'ianov, V. M. Osokin

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статья Редакционная

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Margarete C. Guimarães, Teógenes A. da Silva

Dosímetros eletrônicos, pela praticidade de leitura direta, têm sido cada vez mais utilizados para monitoração individual ou de área para fins de radioproteção em campos de raios X usados em radiologia diagnóstica. Deficiências no desempenho de tais dosímetros em feixes pulsados têm sido publicadas, que não são detectadas pelos procedimentos de calibração e testes de desempenho estabelecidos por normas internacionais somente para feixes contínuos de radiação. No Brasil, não há requisitos de desempenho de dosímetros em feixes pulsados, nem um laboratório que realize ensaios para maior confiabilidade no uso dos dosímetros. Este trabalho objetiva caracterizar a máquina de raios X médico VMI 800 Plus no Laboratório de Calibração de Dosímetros do CDTN/CNEN e estudar a viabilidade da sua utilização para testes de desempenho de dosímetros eletrônicos.