Hasil untuk "Radioactivity and radioactive substances"

João Pedro Oliveira Flores, Renato Semmler, Marina F. Koskinas et al.

This work presents the re-characterization of pneumatic station irradiation position of IEA-R1 reactor for use in k0-INAA method. The thermal-epithermal neutron flux ratio f and the epithermal neutron flux distribution factor α of the IPEN IEA-R1 reactor were determined at the pneumatic irradiation station. To obtain these values, the “bare triple monitor” method was used with 198Au –97Zr – 95Zr.  To evaluate its reproducibility, the temporal variation of these parameters was analyzed, with validation carried out through irradiation of reference materials of geological origin G-S-N (granite) and biological INCT-MPH-2 (mix of herbs). The results obtained for f  and α show that such values ​​are reproducible and compatible with each other, according to the normal Gaussian distribution for up to 1 standard deviation of confidence. The results obtained for the elements detected in the samples agree with the recommended values, with relative errors (bias) less than 10%, except in the case of Mn in G-S-N (16.3%). These results indicate that it is possible to routinely use this method for LAN-IPEN researchers to analyze geological and biological samples.

P. A. Celestino, Roberto Gazola Ortiz, D. Levy

The article discusses the application of food irradiation as a solution for food preservation and safety in naval settings, focusing on the missions of the Brazilian Navy's submarines. Food irradiation, recognized in 37 countries, effectively eliminates parasites, fungi, and bacteria, extending the shelf life of foods without compromising their nutritional and sensory qualities. The research used an electronic questionnaire to assess the knowledge and acceptance of food irradiation among military and civilian personnel of the Navy. Results indicate that before receiving information, 54% of participants were unaware of the technology, and 28% had a negative view of nuclear energy. After exposure to informative materials, 82% of participants expressed willingness to consume irradiated foods, up from 54% previously. The study highlights the importance of education and scientific dissemination for the acceptance of the technology and suggests expanding the study to a larger sample within the Navy. The findings suggest the potential use of food irradiation in Navy ships and submarines, contributing to the health and well-being of crew members.

Sueli da Conceição Teixeira Coelho, T.O. Santos, L. C. Takahashi et al.

Natural radioactivity comes from natural radionuclides present in rocks and soil and from cosmic rays. In addition to gamma-emitting radionuclides, radon stands out, which is a carcinogenic gas. In nature, radon occurs as radioisotopes: 222Rn (half-life time, t1/2,of 3.83 d), 219Rn (t1/2 = 3.92 s) and 220Rn (or thoron, t1/2 = 54.5 s). The World Health Organization (OMS) recommends that it be measured in homes, with the recommended limit being 100 Bq/m3 and the maximum limit being 300 Bq/m3. This work evaluates the origin of natural radiation in a residence in Belo Horizonte, Minas Gerais, Brazil, in which was observed radon concentrations above the limits established by the OMS. The detectors used were: nuclear trace detectors type CR-39, electrets (E-PERM), AlphaGUARD (AG) and the detector RS-230. The result of the 222Rn concentration measured in the electrets in the rooms of the residence varied from 14,8 Bq/m3 to 932 Bq/m3. At this highest point, the result of the average concentration of AlphaGUARD was from 4.78 kB/m3, with a maximum value of 8.5 kBq/m3. The concentration of 220Rn varied Bq/m3  Bq/m3. As this is a basement-type room, the bedroom next door was investigated, in which it is highlighted that the radon concentration of the detector CR-39 was from 445 Bq/m3, AG of 198.2 Bq/m3 with a maximum value of 350 Bq/m3, and electret of 29.6 Bq/m3. Gamma scanning with the RS-230 indicates higher counts on uncoated walls. Measurements of radon in the water showed background concentrations. It is concluded that poor ventilation of the location must be the biggest contributor to the high concentration of 222Rn, which originates mainly from the soil. The thoron concentration was higher in construction materials due to the measurement method. The instrumentation used allows a complete and comparative study between detectors in order to find the origin of natural radionuclides and subsequently suggest appropriate mitigation measures. In future studies, radon concentration in the soil and radon progeny will be measured.

Rennan Franco, Thadeu Conti, Savio Ferreira

The performance of neutronic calculations is a fundamental process for the analysis and design of nuclear reactors. However, due to the intrinsic complexity of these calculations, their solution is nearly impossible, whether through analytical or numerical methods. This work, through the application of a four-layer multilayer perceptron artificial neural network to the neutron transport equation, demonstrates the benefits of using neural computing for electronic calculations.

A. V. Petryakova, L. A. Chipiga, G. A. Andreev et al.

The usage of modern positron emission tomography scanners, in particular with digital detectors, allows obtaining images with better quality, increases the detection of small pathological lesions, reduces scanning time and the activity administered to the patient which leads to a decrease of patient dose as well. However, the values of the quantitative image parameters shift upward, which can lead to significant differences with the quantitative assessment obtained on the previous generation device. In order to compare quantitative assessments obtained on different generations of PET/CT, it is necessary to harmonise quantitative image parameters and perform regular quality control. The aim of current work is the comparison of different methods for harmonization of quantitative image parameters on the example of harmonisation of two PET/CT: Biograph mCT 128 and Biograph Vision 600. NEMA IEC Body phantom filled with 18F solution was scanned in Listmode in two bed positions with overlap in the sphere area during five minutes per bed position. Recovery coefficient used for harmonisation was measured for each sphere of the phantom. Harmonisation between Vision and mCT was performed using two methods: choosing of harmonised reconstruction parameters and EQ.PET technology. The acceptable divergence range between the recovery coefficients for Vision and for mCT is ±10% (20% range). The recovery coefficients measured for reconstruction: 4 iterations and 5 subsets, ToF+PSF, Gaussian 7 mm, matrix 220x220 completely fit within the 20% range. The recovery coefficients measured using EQ = 6 mm (optimal value) fit within the 20% range except the spheres with a diameter of 10 and 13 mm. Both harmonisation methods allow to approximate the quantitative assessment/ However, EQ.PET has limitations for the small lesions. Choosing harmonised reconstruction parameters is the mostwidely used harmonisation method; the EQ.PET allows to harmonise quantitative assessment without the use of multiple reconstruction protocols and losses in visualization ability

Natasha Briggs, Andrea Mantuano Coelho da Silva, Arissa Pickler Oliveira et al.

The IDQBRN/CTEx has a Cs-137 research irradiator whose prupose is to promove the development of research in the area of irradiation of materials, assisting in the acquisition of data and scientific publications in the area. Because it is used for research, it is necessary to verify the distribution of dose point in the irradiator chambers. The purpose of this work is to carry out a five-point dosimetry of each irradiator chamber, using the Fricke chemical dosimeter. This dosimeter is used worldwide in several areas of medical and industrial physics, presenting relevant characteristics such as low cost, uncertainties of less than 3% in industrial applications, in addition to being an absolute and primary dosimeter. Dosimetry was performed in the IDQBRN/CTEx irradiator drawers where the materials to be irradiated are placed in the research irradiator chamber.

P.Ye. Krivitskiy, N.V. Larionova, Yu.V. Baklanova et al.

P.Ye. Krivitskiy, N.V. Larionova, V.N. Monayenko et al.

Fernando Rockembach Mazuim, Daiane Cristini Barbosa Souza, Alexandre D’Agostini Zottis

Interventional radiology (IR) uses minimally invasive image-guided procedures that may require a long duration and deliver high radiation doses to the patient. The most current studies on management and dose reduction in IR have shown to be of fundamental importance in radiation protection practices. The objective of this study was to survey what has been published in the national and international literature on the doses received by patients undergoing IR procedures. It consisted of an integrative review study carried out in Scielo, Pubmed, and INIS databases in the time frame of 2016-2021, using as descriptors: interventional radiology, radiation injuries, radiological protection, dosimetry; and their equivalents in English: interventional radiology, radiation injuries, radiological protection, and dosimetry. The initial sample consisted of 68 full articles related to the theme, published during the study period. Of these, 11 articles were selected and made up the final sample. The results indicate that the use of software in dose management and monitoring has proven to be an important tool in radiological protection. The implementation of dose reduction strategies and increased awareness about the use and effects of radiation result in significantly lower doses to both professionals and patients. No national study on dose management has been identified, highlighting the need to promote the subject in the country. The main recommendations identified were the introduction of technologies and the training of the workers involved.

Deiglys Borges Monteiro, João Manoel Losada Moreira, José Rubens Maiorino

The decommissioning is a complex, costly and hazard process which should be performed in the end of the operational life of a nuclear power plant aiming to reduce the risks offered due to its operation to the environment and public at large. Several kinds of activities are required, with the decontamination and dismantling comprising some of the most important. Several tasks of these activities should be performed in places submitted to high radiation activity, increasing the exposure risks to the labors and costs since more labors and additional time are required aiming to reduce the risks. Despite of it, several of the equipment often used during the plant’s operation have some automation degree, which allow to control it remotely. This technology could be used during the decommissioning, as it is done nowadays in several projects around the world. In the present work, the influence of the adoption of this technology to perform decontamination and dismantling activities would be evaluated regarding the cost reduction. A hypothetical plant would be considered as case of study, to which some idealized assumptions was made. The results demonstrates that to this limit case the cost of the project could be reduced by more than 50%, indicating the potential which the adoption of this technology could have in the project.

Cristian Antonio Wieczorek Villas Boas, Luís Alberto Pereira Dias, Margareth Mie Nakamura Matsuda et al.

The prostate cancer is the second most prevalent disease among men in Brazil, moreover PSMA therapy could change this scenario and its perspectives. IPEN-CNEN is the Brazilian industrial radiopharmacy center that produces radiopharmaceuticals for therapy. The production of 177Lu-PSMA-617 was evaluated in batches until 37 GBq and showed that the combination of ascorbate buffer, adequate radioactive concentration and freezing promoted the stability of the radiopharmaceutical for 48 hours, enabling transport of 177Lu-PSMA-617 to distant regions of the country.

Claudio Rodrigues Corrêa, Taíssi Pepe de Medeiros, Gustavo André Guimarães

Considering the presence of the nuclear issue in the main international forum and agenda as well as the increase in the visibility of the Brazilian Navy's Strategic Projects in the nuclear area, it is necessary to discuss the long-term aspects of this sector of capital importance for Brazil, which is likely to shape the country's development path in the next decades. This paper aims to propose a reflection on future environments concerning nuclear energy in which organs and sectors of Brazilian society (including Brazilian Navy) will act primarily in areas that have direct or indirect implications for maritime power and its interconnections with national development and international relations. This proposal includes discussing the prospective methods that will allow the reflection on the benefits of nuclear technology for Brazil and the international community, the technological challenges that are still facing for its effective implementation, and the possible revisions or redefinitions of formats for non-proliferation agreements. Issues to be addressed include the expansion of the uses of nuclear power and benefits can it provide to the future international community and to the maritime power; the changes that may occur in non-proliferation agreements. In environments of uncertainty and complexities, such as the nuclear area, the use of this methodology stimulates the interaction among the different involved parts, with its cultural, economic and social vision, taking part in defining the possible scenarios. Planners and leaders can gain exceptional ability to anticipate the actions that can drive the real world and produce potent insights.

Marcia Nalesso Costa Harder, Tatiane Andrade, Fernanda M. Reis et al.

A kind of the consumption forms of drinks presentation that has grown and appreciated for the most people is the nectar. The papaya nectar had recognized as a differentiated form of this fruit, where the industry also gains in time of conservation, since the papaya is an extremely perishable fruit. The aim of this study was to evaluate gamma radiation as a way of conserving papaya nectar. Papaya nectar was developed and subjected to gamma radiation at the dose of 1kGy in a dose tax of 0.356 kGy.hour-1 and compared this treatment with the control (0kGy). According to the results obtained, can be concluded that the dose used was adequate for the conservation of this product for the period evaluated reaching the aim.

Ana Paula Nunes de Sá, Elizabeth Harumi Nabeshima, Anna Lucia Casañas Haasis Villavicencio

A ação da radiação ionizante em alimentos ocorre devido a interações de energia que modificam estruturas e atualmente é vista como uma alternativa tecnológica no aprimoramento da massa de alimentos frente às indústrias alimentícias. A farinha temperada, ou "farofa", prato típico brasileiro, apresenta seu maior desafio relacionado à estabilidade oxidativa, devido ao seu alto teor de lipídios. O objetivo deste trabalho foi avaliar os efeitos da radiação ionizante nas propriedades reológicas de bacon, farinha de mandioca temperada ou bacon "farofa" (BF) e bacon desengordurado "farofa" (DBF). As presas foram removidas no mercado local de São Paulo-SP / Brasil,portanto, a farinha foi desengordurada com hexano e irradiada no Centro de Tecnologia de Radiação (CTR) do IPEN-CNEN em uma máquina de feixe de elétrons nas doses de 0 (controle) e 5 kGy (fins sanitários), e analisada quanto às suas propriedades de ligação usando RVA-Rapid Visco Ana-lyzer (perfil de viscosidade) e textura de massa (texturômetro). Os resultados demonstraram que a aplicação da irradiação com feixe de elétrons a 5KGy afetou as propriedades reológicas das farofas em relação à moderada, todos os parâmetros do perfil de viscosidade no RVA e na textura da pasta. Resultando em produtos mais fáceis de serem mastigação durante o consumo.

Anna Cwanek, Jerzy W. Mietelski, Edyta Łokas et al.

Clarysson Alberto Mello da Silva, Carlos Eduardo Velasquez Cabrera, Michel Cleberson Bernardo de Almeida et al.

The spent fuel from a PWR still contains some amount of fissile materials depending on their initial enrichment and the burnup. Thus, spent fuel from PWRs containing about 1.5% of fissile material could be used as fuel for CANDU reactors after some fission products are removed from it. Thus, an important proposal is the DUPIC cycle, where spent fuels from a PWR are packaged into a CANDU fuel bundle using mechanical reprocessing but without the need of chemical reprocessing. When it is refueled with reprocessed fuel, the reactivity of the system increases, and this behavior may affect the safety parameters of the reactor. Therefore, this work studies the neutronic parameters of two reprocessing fuel techniques: AIROX and OREOX, which are evaluated for two different cores configuration. The first one considers heavy water as a moderator and coolant. The second one considers heavy water and light water as moderator and coolant respectively. These studies evaluate the core behavior based on the different number of reprocessed fuels channels and compare them with the reference core. To perform the simulation the MCNPX was used to calculate the effective multiplication factor, fuel temperature coefficient of reactivity, void reactivity coefficient, and neutron flux, which were evaluated at steady state condition for the different cases. The results show that the presence of parasitic absorbers in the reprocessed fuels hardens the neutron spectrum. This behavior provokes an increase in the core reactivity, in the fuel temperature coefficient and in the void reactivity coefficient. Among these parameters, the use of light water reduces the core reactivity but do not improve the fuel temperature coefficient and the void reactivity coefficient.

M. V. Kaduka, L. N. Basalaeva, T. A. Bekyasheva et al.

An article contents the review of the data on the content of polonium and lead content: 210Po, 210Pb in natural entities, obtained from literary sources. The review is given of the existing methods for 210Po and 210Pb content investigation in different entities as well as the analysis of the expedience of the applying of the given polonium and lead content investigation in the foodstuffs technique for the use in a method under development of the radiochemical laboratory of the Institute. More perfect and simple for realization than existing method is given for 210Po and 210Pb content investigation in the foodstuffs from a sample with not more than 1.0 kg weight with minimal detectable activity not more than 0.01 Bq. The results are given of the investigation of 210Po and 210Pb content in the certain types of the foodstuffs sampled in the kitchen gardens located in Leningrad region and bought in the trade network of Saint-Petersburg. Estimation of potential average annual population internal exposure dose (Eint) is carried out due to 210Po and 210Pb content in the investigated foodstuffs which are consumed by the local population. For the estimation of the internal exposure doses we used the data on the food rations of adult population of the settlement of the city type according to the data of Rosstat and Internet-resources. It is demonstrated that population internal exposure dose even from several natural radionuclides taking into account consumption of a limited set of foodstuffs could exceed the exposure dose from artificial radionuclide in tens times even for the territories radioactively contaminated after the Chernobyl NPP accident.

Jin-Hwa Yang, H. Bae, Y. Bang et al.

Y. Sakamoto, Takumi Saito

The Journal of Nuclear Science and Technology covers a variety of topics in the nuclear waste management including the radioactive wastes from decommissioning of the Fukushima Daiichi Nuclear Power Plant (FDNPP). This summary introduces activities presented in recent years. As for the FDNPP, the waste management of the fuel debris and low-level wastes including spent ion exchange media were studied [1–3]. The various types of materials (stainless steel, zircaloy, sintered ceramic, cast-fused zirconia, metal + ceramic, melted inactive simulants, prototypic fuel debris, and irradiated fuel debris simulant) were studied for developing cutting and collecting techniques for the fuel debris. Laser cutting technique for the various simulants of the debris showed good performance, however, confirmatory experiments are still necessary with prototypic fuel debris, in particular with respect to the generation of airborne dusts and fumes [1]. The calculation methodology of radioactivity inventories in wastes at the FDNPP was developed by considering the distribution of radionuclide material balance and constructing calculation flowcharts of the transportation of radionuclide into waste for the reasonable and sustainable waste management for the decommissioning of FDNPP [2]. Furthermore, for safe storage or geological disposal of the spent ion exchange media with high concentration radioactive cesium, zeolitic structures were reported to be effective for containment of Cs [3]. For low-level wastes generating from uranium usage facilities, the treatment of solid and liquid uranium wastes was studied [4–6]. The uranium catalyst, which was used in several industrial fields, became problematic radioactive waste for the treatment and final disposal. Therefore, the dissolution and immobilization method of the spent uranium catalyst was studied and showed over 80% volume reduction and low leachability [4]. On the other hand, the basic treatment method based on the conversion of uranium catalyst of USb3O10 to U3O8 was studied [5]. As for liquid uranium wastes, uranium removal mechanism and performance using graphene oxides functionalized with diethylenetriaminepentaacetic phenylenediamine were shown to be highly efficient for the removal of uranium (VI) from aqueous solution [6]. Several studies for the waste management of the High-Level Waste (HLW) were presented, ranging from a verification technique, a disposal concept, and transportation of nuclear spent fuel transport casks [7–11]. As for the treatment of High-Level Liquid Waste (HLLW), an understanding of varied thermal decomposition behaviors of various nitrates in HLLW is necessary to elucidate a series of phenomena occurring within the cold cap. Gadolinium nitrate, which is one of main compositions of nitrates in HLLW, was chosen as an example, and its thermal decomposition was investigated to gain kinetic parameters to model its consecutive decomposition reactions [7]. The reprocessing technique of high burn-up UO2 and MOX fuels from light-water reactors (LWR) was studied with regard to the safety assessment of geological disposal of HLW [8]. Considering for effects of extended cooling period, it was reported that the waste loading in waste glasses from UO2 and MOX spent fuel could be increased with the current verification technology. In addition, 70% to 90% of Am separation was suggested to be effective in terms of thermal feasibility of buffer material in a geological repository [8]. An unique geological disposal system of wastes was proposed. The method of self-burial of radioactive waste into geological formations using direct heating rock by radiation was proposed [9]. In this concept, radioactive wastes are filled in spherical or cylindrical capsules and disposed into deep geological formation by melting the surrounding rock with irradiation energy of 60Co. Calculations made for granite and salt showed that an average surface 60Co activity of about 1017 Bq/m2 was to be required to achieve a descent velocity of 1 km per year [9]. The effect of gamma irradiation on association of Cu(II) with humic substances (HSs) was studied to understand radiation effects on complexation reactions of radionuclides with organic ligands in nature, which might be important for their migration through host rocks in the geological disposal of wastes [10]. Dose rate in the range 0–100 kGy had marginal impacts on the apparent complex formation constants of HSs with divalent copper ion. Furthermore, the degree of humification was studied for aqueous solution samples of humic acid and fulvic acid which were irradiated with gamma-rays in the dose range of 0–500 kGy at two dose rates, 0.1 and 1 kGy/h. Though the concentration of carboxylic groups decreased drastically with high radiation exposure, no significant change in apparent formation constants was found [10]. JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 2019, VOL. 56, NO. 11, 933–934 https://doi.org/10.1080/00223131.2019.1661308

VALERIA CUCCIA, SANDRO ROGÉRIO NOVAES SELES, ANA CLAUDIA QUEIROZ LADEIRA

Radionuclides may contaminate lubricant oils in nuclear power plants. In Brazil, this kind of waste has been stored in the generator’s facilities, awaiting treatment alternatives. This work intends to investigate a process to treat it for final deposition, using bentonite as sorbent material. This process will result in decontaminated oil, free from radiological control, and radioactive loaded sorbent, with considerable volume reduction of the radioactive waste. The study focuses in cobalt removal from a simulated oil waste (non-active). The production of the simulated waste is described. Bentonite was used for equilibrium time determination, kinetic and adsorption studies. Cobalt adsorption equilibrium was rapidly attained after 30 minutes. The data was used for modelling the system’s kinetic, applying the pseudo first and pseudo second order equation models. Experimental data fitted to pseudo second order model, supporting the assumption that the adsorption is due to chemisorption. Batch sorption tests were conducted and the results fitted to Langmuir and Freundlich sorption models. Both isotherm models chosen for this work did not fit to the experimental data. Thus, these are preliminary results and the studies must be repeated to evaluate data variability and better statistical inference. Other isotherm models must be evaluated to choose the best fitted one and describe the sorption of cobalt on bentonite in oil matrix. Even though, bentonite has considerable potential as sorbent for the removal of cobalt from lubricant oil. Finally, the results might be extended to other kinds of radioactive oils and radioactive organic wastes.