bluuebunny/crossref_metadata_2025 huggingface dataset:
A Clean, Benign, Energy Efficient One-Pot Multicomponent Synthesis and
Bio-evaluation of Novel [1,2,4]Triazolo[1,5-a]quinolines
Authors: Parekh H.P. , Chauhan M.H. , Solanki N.L. , Shah V.H.
Published: July 2021

In present work, a series of novel [1,2,4]triazolo[1,5-a]quinoline derivatives (HP-101-110) have been
synthesized using multi-component reaction at room temperature in the presence of ammonium chloride
as mild, cost effective green catalyst along with water as eco-friendly green solvent. The synthesis of
1,2,4-triazolo[1,5-a]quinolines (HP-101-110) was achieved by two step process. In first step, diversified
Hantzsch pyridine reaction of an appropriate aromatic aldehyde, malononitrile, dimedone and benz
hydrazide using ethanol as a solvent gives N-(2-amino-3-cyano-7,7-dimethyl-5-oxo-4-phenyl-5,6,7,8-
tetrahydro-quinolin-1(4H)-yl)-4-hydroxybenzamide derivatives. In the second step, synthesis of the
final product 2-(4-hydroxyphenyl)-8,8-dimethyl-6-oxo-5-phenyl-6,7,8,9-tetrahydro[1,2,4]triazolo[1,5-
a]-quinoline-4-carbonitriles was achieved by the intramolecular cyclization of step 1 product.The structure
of all the synthesized compounds (HP101-110) has been elucidated by FT-IR, 1H & 13C NMR, mass
spectral data and elemental analyses.
Synthesis of Novel Oxazin Analogs of Thio-4-azaspiro[4.5]decan-3-one
for their Antimicrobial Activity
Authors: Singh Raj Bahadur , Srivastava Krishna , Tiwari Ram Prakash , Srivastava Jyoti
Published: July 2021

The present work reports the synthesis of 4-(1-(substituted phenyl)-1H-naphtho[1,2-e][1,3]oxazin-
2(3H)-yl)-1-thia-4-azaspiro-[4.5]-decan-3-one IV(a-h) by 4-(((substituted phenyl)(2-hydroxynaphthalen-
1-yl) ethyl)amino)-1-thia-4-azaspiro[4.5]decan-3-one with formaldehyde in acetonitrile,
containing a spiro ring obtained from the reaction of cyclohexylidene hydrazine and thioglycollic acid
in DMF (cyclohexanone reacts with hydrazine hydrate in pyridine). The structures of the synthesized
compounds have been established on the basis of elemental analysis, UV-vis absorption spectroscopy,
IR, 1H NMR and mass spectral studies. The in vitro antimicrobial screening of all novel compounds
was done against S. aureus, E. coli, P. aeruginosa and B. subtilis. The activity of compounds IVb, IVc,
IVe and IVf compounds showed moderate to good activity against the tested microbes.
Design, in silico Analysis, Synthesis and Evaluation of Novel Benzofused Nitrogen Containing
Heterocyclic N-Substituted Mercaptobenzimidazole Derivatives as Potential Antimicrobial Agent
Authors: Patil Tejaswini D. , Amrutkar Sunil V. , Jagdale Amol S.
Published: July 2021

Benzimidazole containing mercapto group at the 2nd position is attractive nucleus for the modification
with wider pharmacological activities. The aim of this study is to design benzofused nitrogen containing
heterocyclic derivatives of mercapto benzimidazole using molecular docking. Using an effective procedure,
N-substituted mercapto benzimidazole derivatives was synthesized. The antimicrobial activity of all
the synthesized compounds was tested against four different organisms viz. E. coli, Pseudomonas
aeruginosa, Staphylococcus aureus and Candida albicans. Molecular docking of mercapto
benzimidazole derivatives against DNA gyrase subunit B PDB: 5l3j and Staphylococcus aureus tyrosyltRNA
synthetase PDB:1jij was performed using docking protocol. The compound binds to the active
site of DNA gyrase subunit B (1KZN) in a docking study, indicating that it may have antimicrobial
activity. Compounds MB3 and MB5 have good antimicrobial capacity whereas compound MB4 has the
high activity against Candida albicans.
Quantum Computational, Spectroscopic, NHO and Molecular Docking Studies on
1-Methyl-nicotinamide (MNA): An Antithrombotic, Anti-inflammatory,
Gastroprotective and Vasoprotective Compound
Authors: Kumar Mukesh , Singh Satyavir , Siddiqui Nazia , Javed Saleem
Published: July 2021

In present work, 1-methylnicotinamide (1-MNA) has been investigated theoretically by density functional
theory approach and investigated its vibrational spectroscopy. To complete the structure optimization,
determination of vibrational frequencies and other valuable parameters, B3LYP method used with the
6-311++G(d,p) basis set. Atoms in molecules theory (AIM) had been used to evaluate ellipticity,
isosurface projection by electron localization function and binding energies. The IR and Raman spectra
have also been calculated computationally. NBO analysis employed to determine interactions of donor
and acceptor. Fukui functions and molecular electrostatic potential (MEP) showed reactive regions of
the molecule. UV-vis spectrum calculated using TD-DFT/PCM methods with different solvents.
Thermodynamic properties like free energy, enthalpy and entropy with various temperature were calculated.
By the use of the electrophilicity index, the probability of the bioactive nature of the molecule was
proved theoretically. Protein-ligand interactions calculated and established by molecular docking.
The biological investigations for druglikeness also employed for the (1-MNA).
Study of CuSCN Catalyzed Conjugate Addition Reactions of Grignard Reagents to Substituted Chalcones with Dilithium Tetrachloromanganate and their Biological Activities
Authors: Kale Mohan B. , Jagtap Shrikant B. , Devkate Santosh S.
Published: July 2021

The regioselective 1,4-addition reactions of copper thiocyanate catalyzed Grignard reagents to the substituted chalcones are reported. The homogeneous solution of dilithium tetrachloromanganate is used to transmetallate magnesium by using manganese. It adds regio-selectively to substituted chalcone derivatives and forms 1,4-addition products with higher yield under nitrogen atmosphere and at a lower temperature. It have been observed that manganese from dilithium tetrachloromanganate reagent replaces magnesium from Grignard reagent and adds regioselectively by 1,4-addition manner utilizing copper thiocyanate as a catalyst. The course of the reaction in the absence of dilithium tetrachloromanganate reagent was also studied and obtained a mixture of 1,2-addition and 1,4-addition products. In presence of dilithium tetrachloromanganate reagent, a good regio-selectivity and higher yield of desired 1,4-addition product were obtained. All the synthesized compounds were also evaluated for their antibacterial activity against Staphylococcus aureus (Gram-positive), Escherichia coli (Gramnegative) and antifungal activity against Aspergillus niger.
Determinants of the Price and Non-price Terms of Bank Loans: A Study of Malaysian SMEs
Authors: Wasiuzzaman Shaista
Published: July 2021

The aim of this study is to investigate the determinants of the price and non-price terms of banks loans to SMEs. Responses from a survey questionnaire answered by 74 SMEs that had applied for and were granted bank loans is analyzed using SEM-PLS. The results indicate that the condition and capacity of the SME is significant in influencing interest rates while the SME’s ability to provide collateral, its capital and the character significantly influence the non-price terms. Soft information is highly significant in influencing both the price and non-price terms.
Factors Influencing the Processed Pineapple Export Competitiveness of Thailand
Authors: Wattanakul Thanet , Nonthapot Sakkarin , Watchalaanun Tanawat
Published: July 2021

This study aims to explore the factors influence the competitiveness of Thailand’s processed pineapple exports as well as the impact size of these factors by focusing on canned pineapple (HS 200820) and pineapple juice (HS 200949). This study also determine the competitiveness and market share effects for both products in each market in each Thailand major partner countries. The average price of processed pineapple, GDP per capita and exchange rate were the explanatory variables. The panel data from 2013 to 2017 of 10 partners were used in a panel regression model with pooled OLS, fixed effect and random effect models. The empirical results show that the fixed effect model is the most suitable and that price significantly negatively affected the market share of both products. Moreover, there is a positive effect from GDP per capita on market share for pineapple and the exchange rate positively affected market share for canned pineapple. In addition, Thailand’s pineapple juice market share is less price sensitive than the canned pineapple market. The stable and competitive price are necessary conditions to enhance sustainable export competitiveness under current intense competition. The implementation of effective exchange rate management to prevent massive fluctuation is a crucial supporting mechanism to achieve this target. Moreover, the appropriate devaluation is other essential policy to enhance sustainable price competition under the tension competitive environment leads to accelerate the continue market shares in important markets.
Corporate Governance’s Role in the Risk-Return Paradox - New Evidence from Indian Firms
Authors: Dasgupta Ranjan
Published: July 2021

Prior empirical research emphasises ‘troubled’ firm context and ‘quality management’ perspective as reasons for a ‘paradoxical’ or negative risk-return association for firms. But, to the best of our knowledge, no studies examine the role of individual corporate governance mechanisms in influencing such a ‘paradox’. Therefore, the study investigates this issue by classifying 675 sample Indian firms over the period 2000-2017 into high performing and low performing firms in line with the strategic reference point theory and the behavioural theory. To fulfil study objectives, it uses four different firm-return measures and estimate firm-level risk with standard deviations of each return measures previous 5 years’ values on a rolling basis. In the univariate model, the study uses the notion of target (reference) return level under firm’s own and social aspiration levels in time-variant and market cycles contexts, and then compute Kendall’s correlations in between distance from such targets and their standard deviations. The study also carries out a multivariate regression model with necessary controls to further validate its univariate findings. The study results report significant influential role that board size and women directors’ presence play in both high and low performing firms’ ‘paradoxical’ risk-return association. On the contrary, board meetings, busy board and board tenure develops a risk-return ‘paradox’ for high performing firms only. These results hold true across my return measures, strategic reference points, market cycles and corporate governance regimes after controlling for firm- and industry-level heterogeneities under both univariate and multivariate analyses.
Bcl2 negatively regulates Protective Immune Responses During Mycobacterial Infection
Authors: Singh Aayushi , Anang Vandana , Verma Chaitenya , Saraswati Shakuntala Surender Kumar , Rana Ankush Kumar , Bandyopadhyay Upasana , Chadha Attinder , Natarajan Krishnamurthy
Published: July 2021

We previously reported that M. tb on its own as well as together with HIV inhibits macrophage apoptosis by upregulating the expression of Bcl2 and Inhibitor of Apoptosis (IAP). In addition, recent reports from our lab showed that stimulation of either macrophages or BMDCs results in the significant upregulation of Bcl2. In this report, we delineate the role of Bcl2 in mediating defense responses from dendritic cells (BMDCs) during mycobacterial infection. Inhibiting Bcl2 led to a significant decrease in intracellular bacterial burden in BMDCs. To further characterize the role of Bcl2 in modulating defense responses, we inhibited Bcl2 in BMDCs as well as human PBMCs to monitor their activation and functional status in response to mycobacterial infection and stimulation with M. tb antigen Rv3416. Inhibiting Bcl2 generated protective responses including increased expression of co-stimulatory molecules, oxidative burst, pro-inflammatory cytokine expression and autophagy. Finally, co-culturing human PBMCs and BMDCs with antigen-primed T cells increased their proliferation, activation and effector function. These results point towards a critical role for Bcl2 in regulating BMDCs defense responses to mycobacterial infection.
Neutron darkfield imaging of fiber composites
Authors: Hilger André , Kardjilov Nikolay , Lange Axel , Kupsch Andreas , Hentschel Manfred P. , Manke Ingo
Published: July 2021

While X-ray based darkfield imaging with grating interferometers is already widely used, darkfield imaging with neutrons has still a relatively small user community focused mostly on magnetic materials. Here, we demonstrate the application of neutron darkfield imaging byTalbot-Lau type grating interferometry to fiber reinforced plastics. Common carbon and glass fiber composites have been investigated including characteristic damage structures. The darkfield images show a strong signal response caused by fiber delamination, suitable fiber direction, particles, pores and cracks. The basic principles of neutron darkfield imaging applied to fiber composites are highlighted.
Malaria-free Certification in China: Achievements and Lessons Learned from the National Malaria Elimination Programme
Authors: Feng Jun , Zhang Li , Xia Zhi-Gui , Zhou Shui-Sen , Xiao Ning
Published: July 2021

Malaria was once one of the most severe public health problems in China. However, after 70 years of integrated interventions, substantial progress has been made, and remarkable milestones have been met in malaria elimination in China. On June 30th, 2021, China was officially certified as a malaria-free country by the World Health Organization. This paper highlights the achievements of, and lessons learned from the malaria elimination programme.
Early Postoperative Results of On-Pump Coronary Endarterectomy: Is Gender a Risk Factor?
Authors: Eris Cüneyt , Engin Mesut , Sunbul Sadık Ahmet , As Ahmet Kagan , Erdolu Burak
Published: July 2021

Background: Coronary endarterectomy (CE) combined with coronary artery bypass grafting (CABG) is an effective but still controversial surgical strategy for the treatment of diffuse coronary artery disease. In this study, we aimed to investigate the impact of gender differences on operative and early postoperative results of patients who underwent CABG with CE.
Methods: This retrospective study included 141 patients who had undergone CE combined with CABG from January 2015 to December 2020, as well as 141 patients without CE as the control group. First, patients with and without CE were compared. Next, patients undergoing CE were divided into 2 groups according to gender (group 1, male patients; group 2, female patients).
Results: Of the 141 patients who underwent CE combined with on-pump CABG, 95 (67.3%) were male, and median age was 66 years (range 58 to 71.2). Of the 141 patients who underwent isolated on-pump CABG, 99 (70.2%) were males, and median age was 63 years (range 41 to 80.4). The data for these 2 groups (with and without CE) were compared. Previous percutaneous coronary intervention (PCI), presence of diabetes mellitus, and perfusion time were significantly more common in the CE group. There were 95 patients in group 1, with a median age of 65 years (range 58 to 69), and 46 patients in group 2, with a median age of 66 (64 to 71.2). There were no difference between the groups in terms of age, body mass index, hyperlipidemia, chronic obstructive pulmonary disease, peripheral artery disease, or previous coronary intervention. The need for positive inotropic support and postoperative atrial fibrillation were found to be significantly more common in group 2 (P = .022 and .039, respectively). Defibrillation after releasing the aortic cross clamp was also significantly more common in group 2 (P = .025).
Conclusion: In our study, the need for defibrillation after aortic cross-clamp releasing in the perioperative period, the need for inotropic support and the incidence of atrial fibrillation in the post-operative period, increased significantly in the female gender. CE can be performed safely in both genders with acceptable mortality and morbidity rates.
ALGUNOS RESTOS ARQUEOLÓGICOS DEL PERIODO PRE-PARACAS EN EL VALLE DE PALPA, ICA
Authors: Mejía Xesspe Toribio
Published: July 2021

El departamento de Ica, como es bien sabido, es uno de los más ricos en yacimientos arqueológicos, porque allí se encuentran los testimonios de la industria humana que pertenecen a tres horizontes culturales de la región
UN CONTEXTO FUNERARIO DEL HORIZONTE MEDIO PROCEDENTE DE CERRO COLORADO, HUACHO
Authors: Van Dalen Luna Pieter , Tello Cuadros Roberto C. , Grados Rodríguez Hans G.
Published: July 2021

Se presenta las características de un contexto funerario del Horizonte Medio recuperado del complejo funerario de Cerro Colorado, en el extremo meridional del valle de Huaura. Entre los años 2014 y 2015 el proyecto de Investigación Arqueológica Chancay-Huaral-Atavillos, logró excavar más de 2000 contextos funerarios de este extenso complejo funerario, el más grande de toda la costa central peruana.
LA RELACIÓN A FINALES DEL PERÍODO HORIZONTE TEMPRANO E INTERMEDIO TEMPRANO EN CONVENTOMOQO, VALLE DEL CUSCO
Authors: Delgado González Carlos
Published: July 2021

Este trabajo trata sobre la interacción de los estilos cerámicos Chanapata Derivado y los estilos del Período Intermedio Temprano como Qotakalli y una cerámica “Local” durante este período e inicios del Horizonte Medio en el sitio arqueologico de Conventomoqo en el valle del Huatanay.Conventomoqo es un lugar interesante donde se tiene una columna estratigráfica desde el Período Horizonte Temprano hasta la época Inca, lugar que inicialmente fue identificado por Bauer en su prospección intensiva del valle del Cusco (2008) y por el Instituto Nacional de Cultura del Cusco. Las excavaciones arqueológicas nos han permitido obtener algunos derroteros para plantear que el estilo ceramico Chanapata Derivado siguio produciendose y utilizandose en Conventomoqo cuando el estilo Qotakalli se encontraba densamente difundido en el valle del Huatanay. Ademas los datos de la excavación y el análisis de la cerámica nos ha conducido a plantearnos una interrogante sobre un estilo de cerámica a la que denominamos “Local” para el valle del Cusco y sería contemporánea con Qotakalli.
Differentiation of the content of physical education lessons taking into account indicators of the state of the cardiorespiratory system of pupils in the secondary school
Authors: Aghyppo Oleksandr , Mameshyna Marharyta , Masliak Iryna
Published: July 2021

Purpose: to study the dynamics of the cardiorespiratory system indicators of 13-14-year-old pupils under the influence of the differentiated content of physical education lessons. Material and methods: 103 pupils of the comprehensive school No. 150 of Kharkov took part in the research. The methods were used in the research: theoretical analysis and synthesis of scientific-methodological literature; biomedical methods (tonometry, pulsometry, and spirometry); pedagogical experiment; methods of mathematical statistics. Results: the level of functioning of the cardiorespiratory system of 13-14-year-old pupils is below average. Taking into account the indicators of the functional state of the cardiovascular and respiratory systems of 13-14-year-old pupils, the content of physical education lessons is differentiated; the development and implementation of physical exercise complexes aimed at increasing the above indicators. Conclusions: as a result of the introduction of the developed physical exercise complexes in indicators characterizing the state of cardiovascular and respiratory systems of pupils of experimental groups, there were reliable positive changes in all the studied parameters (p<0,05-0,001). As a result, the state of the cardiorespiratory system of 13-14-year-old pupils increased from below average to average.
Keywords: physical health, cardiovascular system, respiratory system, physical education, 13-14-year-old pupils.
A Method for the evaluation of knowledge management systems
Authors: Grecco Claudio Henrique dos Santos , Augusto Silas Cordeiro , Souza Jaqueline Tavares Viana de , Carvalho Paulo Victor Rodrigues , Davila Adriana Loureiro
Published: July 2021

The explicit and tacit knowledge of workers constitute as valuable resources, as they enable organizations to perform their functions successfully. Such knowledge is derived from the qualification and experience of workers. On the other side, there are factors that favor the loss of this knowledge in organizations, as for example, the natural aging of workers and consequently the retirement and staff turnover. Because of these reasons, it becomes important for any organization to seek the preservation of its explicit and tacit knowledge. The Knowledge Management seeks to assist in the tasks of identification, organization, preservation and transmission of such knowledge. At the Nuclear Engineering Institute, three systems were developed and implemented to help in the Knowledge Management area: CarpeDIEN, a repository of research data based on the DSpace software; the “Nuclear Energy in Magazines”, a peer-reviewed academic journals management system based on the Open Journal Systems software; and WikiIEN, a wiki based on the MediaWiki software. Each of these systems presents a different proposal and workflow. The objective of this paper is to present the characteristics of each system, a method to compare them based on criteria presented in the literature and to point their weaknesses. The results showed that the method is a proactive tool to provide a basis for choosing the most appropriate system for a given need in an organization.
Experimental evaluation of natural convection in the IPR-R1 Triga research reactor at 264 kW and 105 kW
Authors: Mesquita Amir Zacarias
Published: July 2021

In order to study the safety aspects connected with the permanent increase of the maximum steady state power of the IPR-R1 Triga Reactor of the Nuclear Technology Development Center (CDTN), experimental measurements were done with the reactor operating at power levels of 265 kW and 105 kW, with the pool forced cooling system turned off. A number of parameters were measured in real-time such as fuel and water temperatures, radiation levels, reactivity, and influence of cooling system. Information on all aspects of reactor operation was displayed on the Data Acquisition System (DAS) shown the IPR-R1 online performance. The DAS was developed to monitor and record all operational parameters. Information displayed on the monitor was recorded on hard disk in a historical database. This paper summarizes the behavior of some operational parameters, and in particular, the evolution of the temperature in the fuel element centerline positioned in the core hottest location. The natural circulation test was performed to confirm the cooling capability of the natural convection in the IPR-R1 reactor. It was confirmed that the IPR-R1 has capability of long-term core cooling by natural circulation operating at 265 kW. The measured maximum fuel temperature of about 300 oC was lower than the operating limit of 550 oC. It has been proven that without cooling in the primary the gamma dose rate above reactor pool at high power levels was rather high.
Neutronic Evaluation of MSBR System Using MCNP Code
Authors: Silva Clarysson Alberto Mello da , Vieira Alana Lima , Magalhães Isabella Resende , Pereira Claubia
Published: July 2021

The concept of Molten Salt Reactor use Th to breed fissile 233U, where an initial source of fissile material needs to be provided. However, there is no available 233U and so; the fissile fuel supply is one of the unresolved problems. Thus, it is necessary to use existing fissile materials such as 235U or Pu to produce 233U. Current studies analyze the fuel transition from 235U/Th or Pu/Th to 233U/Th and, in this context, the present work evaluates the criticality and the neutron flux of MSBR (Molten Salt Breeder Reactor) considering the fuel: (i) mix of Th and enriched U; (ii) the combination of Th and reprocessed Pu; and (iii) matrix of reprocessed Pu/minor actinides (MAs) and Th. The goal is to verify which of these fuels can be used as initial fissile supply. The MSBR core was simulated by MCNPX 2.6.0 code and the criticality model presents similar behavior of previous studies. The results show that reprocessed fuels could have a potential to be used as initial fissile supply, but these fuels present a neutron flux profile less flattens than traditional 233U/Th. It is possible that a new distribution of fuel elements may improve this profile and future simulations will be performed to evaluate this behavior. The uranium, must has high enrichment value to be used as initial seed.  Other studies need be performed to evaluates the uranium enrichment and the U/Th ratio that produces similar core criticality to traditional fuel.
Modified methodology for determining the temperature profiles of inverted u-tubes steam generators used in pwr power plants
Authors: Curi Marcos Filardy , Zotin José Luiz Zanon , Chaves Luiz Carlos
Published: July 2021

The most common and reliable methodology for determining temperature profiles of Inverted U-tubes Steam Generators is using Computational Fluid Dynamics (CFD) programs. In this work, we developed a modified methodology, using the Wolfram Mathematica software, in order to determine, with good approximation, the temperature profiles of these kind of equipment. The first step was to determine expressions for the physical properties of the water in the operational conditions, like density, thermal conductivity, specific heat and dynamic viscosity. Geometrical parameters like tubes diameter and sub-channel flowing area, as well as the flow parameters like flow mass of primary and secondary fluid, were also considered for determining the numbers of Reynolds, Prandtl, Nusselt and, consequently, the variation of convective coefficients and the global heat transfer coefficient. With subroutines that use the method of the lines we were able to solve the partial differential equations applied to parallel and countercurrent heat exchangers with no phase change. The U-tubes SG were divided in two regions which the first one was calculated considering a parallel heat exchanger and the second one was calculated considering a countercurrent heat exchanger, depending on the flow direction of the primary and secondary circuit. During the phase change, a constant variation of the enthalpy was considered, making the primary fluid temperature decrease following a linear behavior. Using the developed methodology called “Enthalpy Ruler”, the encountered results were considered adequate, since the defined lengths are compatible with the constant variation of the enthalpy from the compressed liquid to saturated steam.
Small break loss of coolant accident of 200 cm² in cold leg of primary loop of Angra2 nuclear power reactor evaluation
Authors: BORGES EDUARDO MADEIRA , SABUNDJIAN GAIANÊ
Published: July 2021

The aim of this paper is evaluated the consequences to ANGRA 2 nuclear power reactor and to identify the flow regimes, the heat transfer modes, and the correlations used by RELAP5/MOD3.2.gama code in ANGRA 2 during the Small-Break Loss-of-Coolant Accident (SBLOCA) with a 200cm2 of rupture area in the cold leg of primary loop. The Chapter 15 of the Final Safety Analysis Report of ANGRA 2 (FSAR-A2) reports this specific kind of accident. The results from this work demonstrated the several flow regimes and heat transfer modes that can be present in the core of ANGRA 2 during the postulated accident. The results obtained for ANGRA 2 nuclear reactor core during the postulated accident were satisfactory when compared with the FSAR-A2. Additionally, the results showed the correct actuation of the ECCS guaranteeing the integrity of the reactor core.
One-step coupled calculations (Serpent-OpenFOAM) for a fuel rod of the IPR-R1 triga reactor
Authors: Vieira Tiago Augusto Santiago , Gonçalves Rebeca Cabral , Machado Izabella Cristina de Paiva , Vidal Guilherme Augusto Moura , Castro Higor Fabiano Pereira , Ribeiro Nataly Lamounier , Filho Marcos Pais Barroso , Santos Wilker Gustavo Ferreira , Campolina Daniel de Almeida Magalhães , Barros Graiciany de Paula , Silva Vitor Vasconcelos Araújo , Dos Santos André Augusto Campagnole
Published: July 2021

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.
Quality assurance program for Angra 1 licence renewal and long-term operation
Authors: MORGHI YOUSSEF , Mesquita Amir Zacarias , MAIA Ana Rosa BALIZA
Published: July 2021

In Brazil, according to Cnen standard, a nuclear power plant has authorization to operate for 40 years. Angra 1 commercial operation started in 1985 and it has license to operate until 2024. Eletronuclear aims to extend the operation of the Angra 1 plant from 40 to 60 years. To obtain the license renewal by more than 20 years (long-term operation), Eletronuclear will need to meet the requirements of 10 CFR Part 54, Cnen NT-CGRC-007/18 and NT-CGRC-008/18 (Cnen technical notes). To obtain a license renewal to a long-term operation it is necessary to demonstrate that the plants will operate according to safety requirements, through analysis, testing, aging management, system upgrades, as well as additional inspections. Plant operators and regulators must always ensure that plant safety is maintained and, when it is possible, strengthened during the long-term operation of the plant. One of the documents to obtain a license renewal to a long-term operation is the Quality Assurance Program (QAP). Angra 1 has a QAP according to 10CFR 50 App B and Cnen NN 1.16 for safety related items. However, according to 10 CFR50.34, Nureg-1800 Appendix A.2, Nureg-1801 Appendix A-1 of Nuclear Regulatory Commission (NRC) and NT-CGRC-007/18 and NT-CGRC-008/18 of Cnen, the QAP needs to include the items that are not safety related but are included in the Aging Management. This article will discuss the Angra 1 QAP for the license renewal to a long-term operation according the standards approved by Cnen.
Thermal hydraulic analysis of a PWR loaded with annular fuel rods
Authors: De Souza Wallen Ferreira , Veloso Maria Auxiliadora Fortini , Costa Antonella Lombardi , Pereira Clubia
Published: July 2021

In 2006, the final report of the MIT Center for Advanced Nuclear Energy Center the project entitled High Performance Fuel Design for Next Generation PWR’s presented the proposal of an internal and external cooled ring fuel with the objective of increasing the power density of a PWR reactor without compromising the safety margins of the installation. The thermal hydraulic conditions were calculated with the aid of the VIPRE subchannel code, which is a widely used tool in the analysis of nuclear reactor cores. STHIRP-1 is a subchannel code that has been developed at the Departamento de Engenharia Nuclear /UFMG. In order to evaluate the capacity of the STHIRP-1 program, mainly in relation to the thermal model, the new fuel concept was analyzed. The results were compared with those performed with the VIPRE code presented in the reference document.
DEVELOPED LIQUID FILMS FALLING AROUND TAYLOR BUBBLES INSIDE VERTICAL STAGNANT COLUMNS
Authors: De Azevedo Marcos Bertrand
Published: July 2021

The present work reports an experimental study of developed liquid films falling around single Taylor bubbles inside vertical tubes containing stagnant liquids. Experiments were carried out in acrylic tubes with 2.0 m length and inner diameters of 0.019, 0.024 and 0.034 m. Five water-glycerin mixtures were used, corresponding to film Reynolds number（Ref）ranging from 2 to 7650. A pulse-echo ultrasonic technique was applied to measure the rise velocity of the bubble and the equilibrium thickness of the liquid film. These parameters together with the calculated standard deviation of the equilibrium film thickness provided information about the development of waves on the gas-liquid interfaces, which could be related with the laminar-turbulent transition of liquid films falling around Taylor bubbles. The results indicated that the wave amplitudes increased sharply for Ref> 1000. This value of Ref is in agreement with literature concerning the laminar-turbulent transition for free falling films on vertical surfaces.
Thermal-hydraulics validation of CFD code for light water nuclear reactors against benchmark experimental results
Authors: Monteiro Deiglys Borges , Gonzalez Duvan Alejandro Castellanos , Maiorino José Rubens
Published: July 2021

The cooling of a nuclear reactor depends on a suitable fluid flow pattern among its fuel elements aiming the removal of heat produced in the fuel. In case of light water reactors, an excess of heat drives the fluid to change its phase from liquid to vapor, significantly reducing its capacity to remove heat and leading the reactor to a Loss of Coolant Accident. Numerical simulations using a CFD code is a suitable tool to address this kind of problem and explore the conditions that should be avoided during the reactor operation. The commercial CFD codes had proven to be reliable to simulate with a high accuracy and confidence the thermal-hydraulics of a sort of equipment and systems, avoiding spending efforts and financial resources in the development of new codes that, essentially, perform the same tasks. Despite of it, the CFD codes must be validated, such as against experimental results. To comply with this objective, a benchmark fuel element was purposed and experimentally essayed to provide experimental results for CFD codes calibration. The results of this essay are provided to the four types of subchannels for a 5x5 PWR fuel element, with results provided as density and void fraction. This work presentes the preliminary results obtained with CFD numerical simulations using the ANSYS-CFX® code for the central subchannel with active rods for stead state operation. The results demonstrated that the ANSYS-CFX® is adequate to simulate with high accuracy the flow in this subchannel.
Simulation of transients in ads reactors in three-dimensional geometry
Authors: Carneiro José Rafael Nicolao , De Lima Zelmo Rodrigues , Gonçalves Alessandro da Cruz
Published: July 2021

Accelerator-Driven System, ADS, belong to the new generation of advanced reactors being developed that promise to drastically reduce the life of radioactive waste by, for example, the transmutation process. Subcritical reactor designs of the ADS type have attracted worldwide attention and are the subject of research and development in several countries. The purpose of this work is to simulate transients associated with ADS. It adopted the neutron diffusion model that leads the spatial kinetics equations. These equations are solved by the known numerical method of finite differences. The simulations are performed considering transients related to the variations in the intensity of the proton flux provided by the particle accelerator acting in a sub-critical reactor in three-dimensional geometry for two energy groups and six groups of delayed neutron precursors.
Entering new markets: nuclear industry challenges
Authors: Freire Luciano Ondir , De Andrade Delvonei Alves
Published: July 2021

Nuclear ship propulsion and isolated islands energy supply are unexplored markets for nuclear vendors. Carbon taxes and fuel regulations may make fossil fuels more expensive. Such markets pay more for energy because of organization and transport costs and use of small machines, which are less efficient than grid generators. The goal of this work is to find the measures the nuclear industry needs to take to get into new potential markets. This work shows the different actors and their interests and points the natural or physical constraints they face. Considering interests and constraints, this work named the most probable market niches where nuclear power may beat other power sources. After considering natural constraints, this paper analyses human-generated constraints and presents a way on how to mitigate or solve them. This study shows that nuclear industry needs to take technical, administrative, and political measures before nuclear power arrives to a wider market. This work is based on literature review and qualitative analysis and cannot point precise thresholds where nuclear power should be competitive. Future work will consist of statistical analysis to find precise thresholds to help in the decision-making process.
Potential advantages of molten salt reactor for merchant ship propulsion
Authors: Freitas Neto Luiz Gonzaga de , Freire Luciano Ondir , Dos Santos Adimir , De Andrade Delvonei Alves
Published: July 2021

Operating costs of merchant ships, related to fuel costs, has led the naval industry to search alternatives to the current technologies of propulsion power. A possibility is to employ nuclear reactors like the Russian KLT-40S, which is a pressurized water reactor (PWR) and has experience on civilian surface vessels. However, space and weight are critical factors in a nuclear propulsion project, in addition to operational safety and costs. This work aims at comparing molten salt reactors (MSR) with PWR for merchant ship propulsion. The present study develops a qualitative analysis on weight, volume, overnight costs, fuel costs and nuclear safety. This work compares the architecture and operational conditions of these two types of reactors. The result is that MSR may produce lower amounts of high-activity nuclear tailings and, if it adopts the 233U-thorium cycle, it may have lower risks of proliferating nuclear weapons. Besides proliferation issues, this 4th generation reactor may have lower weight, occupy less space, and achieve the same levels of safety with less investment. Thus, molten salt regenerative reactors using the 233U-thorium cycle are potential candidates for use in ship propulsion.
Effect of compaction pressure on the thermal conductivity of UO2-BeO-Gd2O3 pellets
Authors: Camarano Denise das Mercês , Dos Santos Ana Maria Matildes , Mansur Fábio Abud
Published: July 2021

The (U,Gd)O2 fuels are used in pressurized water reactors (PWR) to control the neutron population in the reactor during the early life with the purpose of extended fuel cycles and higher target burnups. Nevertheless, the incorporation of Gd2O3 in the UO2 fuel decreases the thermal conductivity, leading to premature fuel degradation. This is the reason for the addition of beryllium oxide (BeO), which has a high thermal conductivity and is chemically compatible with UO2. Pellets were obtained from powder mixtures of the UO2, Gd2O3 and BeO, being the oxide contents of the beryllium equal to 2 and 3wt%, and the gadolinium fixed at 6wt%. The pellets were compacted at 400, 500, 600, and 700 MPa and sintering under hydrogen reducing atmosphere. The purpose of this study was to investigate the effect of BeO, Gd2O3 and compaction pressure on the thermal conductivity of the UO2 pellets. The thermal diffusivity and conductivity of the pellets were determined from 298 K to 773 K and the results obtained were compared to UO2 fuel pellets. The thermal diffusivity was determined by Laser Flash and Thermal Quadrupole methods and the thermal conductivity was calculated from the product of thermal diffusivity, the specific heat capacity and density. The sintered density of the pellets was determined by the xylol penetration and immersion method. The results showed an increase in the thermal conductivity of the pellets with additions of BeO and with the compaction pressure compared to the values obtained with UO2 pellets.
Knowledge base about risk and safety of nuclear facilities to support analysts and decision-makers
Authors: Souza Vieira Neto Antonio , Muñoz Oliva Amaury , Da Silva Pagetti de Oliveira Patrícia , Costa Hunold Marcos , Lago Jacques Sauer Maria Eugênia , Andrea Vinicius
Published: July 2021

Epistemic uncertainty (related to lack of knowledge), often found in the documentation of nuclear facility engineering projects, can affect the decision-making process of managers and analysts on safety and risk issues. This article conceptualizes the nature of the major uncertainties involved in engineering projects and describes a knowledge base developed to gather data and information related to the project of an Open-Pool Light-water Research Reactor (OPLRR) and whose purpose is to assist professionals who work in the areas of nuclear facilities. To reduce the epistemic uncertainties that may arise in the project, the OPLRR knowledge base is designed with a set of information that allows identifying and facilitating the forwarding of solutions to address inconsistencies, and /or pending issues that may exist in the project. In this sense, the information and the documents related to the project are organized in a graphical and hierarchical architecture, allowing the knowledge base users to quickly and easily obtain information regarding the systems, processes, equipment, and components of the project. Besides that, a set of documents containing descriptions, reliability data, and some other information about the systems and components are specially created to the knowledge base and it is crucial to reduce epistemic uncertainties, once it raises the issues and the inconsistencies of the project, as well as it clarifies the interrelations between the systems, the functioning of the equipment, their failures modes and the consequences of their failures, and some other data, which are not originally contained in the documents of the project.
Reliability and redundancy allocation analysis applied to a nuclear protection system
Authors: Busse Alexander Lucas , Moreira João Manoel Losada
Published: July 2021

Brazil is constructing with national technology two small nuclear reactors for propulsion and for radioisotope production with thermal power levels between 20 and 50 MW. These nuclear reactors fit more in the class of small modular reactors (SMR) than in the class of large nuclear power plants. In this article we apply the design approach of SMRs to propose an architecture of reactor protection systems for the small reactor under construction in the country. To do that the probabilistic analysis of the architecture of a nuclear reactor protection system is evaluated to determine the sensitivity of the components through an Reliability Block Diagram modeling. It was evaluated the modification of the architecture and the addition of redundancies when using components with lower life time than the components usually used for this purpose. The results showed that after one year of operation, the reference RPS system presents a failure probability of 0.17 %. The modified system, with components with lower life time, presents a point reliability value only 0.070 % lower than the reference one, but this difference grows exponentially over time, and in 10 years of operation it can reach values above 95%. Using equipment with lower life time characteristics implies a greater number of redundancies and, additionally, a greater number of maintenance procedures and spare parts. Therefore, this technical feasibility analysis should consider a RAM simulation as well.
Overview of the seismic probabilistic safety assessment applied to a nuclear installation located in a low seismicity zone
Authors: De Oliveira Ellison Amaro , De Oliveira Patricia da Silva Pagetti , Neto Miguel Mattar , Maturana Marcos Coelho
Published: July 2021

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.
Methane flux and gas hydrate accumulations in the Sea of Okhotsk and their ecological aspects
Authors: Sokolova N.L. , Telegin Yu. A. , Obzhirov A.I.
Published: July 2021

Methane is one of the important representatives of the organic substances in the atmosphere (for example, an increase of methane content in the atmosphere can affect enhancing the greenhouse effect). Gas hydrates are an essential part of links in the methane cycle and the accompanying fluxes of other gases. The research object in this paper is the Sea of Okhotsk, where gas hydrate fields and active submarine gas discharge areas were found. The study of methane fluxes is relevant both for the Sea of Okhotsk and the World Ocean. From 1984 to 2015, the background and anomalous methane fields were explored in the Sea of Okhotsk as a result of gas geochemical research carried out by scientists of the Gasgeochemistry Laboratory (POI FEB RAS). The flux of natural gas became stronger from the sources to the seafloor, from the seafloor to the water, and, finally, to the atmosphere due to renew of fault zones. Moreover, the amount of methane vents on the Sakhalin slope has increased from 2-3 vents to more than 400. The most representative hydroacoustic anomalies “flares” mapped direct methods study methane hydrates. The received outcomes indicate the urgency of the study of methane fluxes and the formation-dissociation mechanism of gas hydrates, and the influence of natural gas from hydrocarbon sources on the environment.