scholarly journals Analysis of the NUPEC PSBT Tests with FLICA-OVAP

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Matteo Bucci ◽  
Philippe Fillion
Keyword(s):  
Nuclear Power ◽  
Experimental Tests ◽  
Physical Models ◽  
Rod Bundles ◽  
Two Phase ◽  
Experimental Database ◽  
Boiling Crisis ◽  
Power Increase ◽  
Relevant Role

This paper discusses the results of a computational activity devoted to the prediction of two-phase flows in subchannels and in rod bundles. The capabilities of the FLICA-OVAP code have been tested against an extensive experimental database made available by the Japanese Nuclear Power Energy Corporation (NUPEC) in the frame of the PWR subchannel and bundle tests (PSBT) international benchmark promoted by OECD and NRC. The experimental tests herein addressed involve void fraction distributions and boiling crisis phenomena in rod bundles with uniform and nonuniform heat flux conditions. Both steady-state and transient scenarios have been addressed, including power increase, flow reduction, temperature increase, and depressurization, representative of PWR thermal-hydraulics conditions. After a brief description of the main features of FLICA-OVAP, the relevant physical models available within the code are detailed. Results obtained in the different tests included in the PSBT void distribution and DNB benchmarks are therefore reported. The relevant role of selected physical models is discussed.

VVER-440 Steam Generator’s Two-Phase Flow Analysis

2016 ◽  
Vol 821 ◽  
pp. 57-62
Author(s):  
Lukas Joch ◽  
Roman Krautschneider
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Steam Generator ◽  
Nuclear Power ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Reactor Power ◽  
Physical Models ◽  
Two Phase ◽  
Ansys Fluent

The subject of this report is creation of three-dimensional thermal hydraulic model of horizontal steam generator for Dukovany nuclear power plant. A procedure is presented for simulation and analysis of secondary side of PGV-440 steam generator for nominal and increased reactor power. A two-fluid approach is applied for modeling physical processes inside the steam generator. Physical models were implemented in ANSYS Fluent CFD environment using User Defined Functions (UDFs). Results from this thermal hydraulic numerical model can be used for various other subsequent nuclear power plant operations and safety analysis.

Role of analytical transmission EM in the study of Zr Pressure-tube alloys

1992 ◽  
Vol 50 (1) ◽  
pp. 206-207
Author(s):  
G.G. Weatherly ◽  
A. Perovic ◽  
V. Perovic ◽  
G.R. Purdy
Keyword(s):  
Heat Treatment ◽  
Nuclear Power ◽  
Cold Work ◽  
Neutron Cross Section ◽  
Zirconium Alloys ◽  
Stress Relief ◽  
Two Phase ◽  
Β Phase ◽  
Pressure Tubes

Zirconium alloys are widely used in the Candu nuclear power generating system because of their unique combination of creep and corrosion resistance properties coupled with a low neutron cross section. The Zr-2.5 wt%Nb alloy has been extensively studied because it is the key component in pressure tubes. Pressure tubes are fabricated by extrusion in the two phase (α + β) field in the binary phase diagram, followed by cold work and stress relief heat treatments. As a result of this treatment, the alloy has a complex microstructure consisting of a duplex α + βzr or α + βNb structure (depending on the particular heat treatment), superimposed on which is a dislocation structure associated with the working operation. Typical microstructures are shown in Figs.l and 2. If the alloy is quenched from the β phase field (1000° C), a Widmanstätten α-βzr microstructure is produced (Fig.la). In the extruded state (Fig.lb), the βZr phase is now elongated and linked by a substructure which contains both <a> and <c> dislocations. Cold working followed a stress relief heat treatment at 400°C for 24 hrs introduces predominantly <a> dislocations, while the βZr phase (which is metastable) has decomposed to form discrete arrays of βNb (Fig-lc). Examples of the dislocation substructure are shown in Fig.2. Boundaries containing both <a> and <c> dislocations are observed. The misorientation at the boundaries is typically a few degrees. They are often stepped or faceted. In Fig.2 the steps correspond to a <c> dislocation which has dissociated to form two <c>/2 dislocations.

THE MECHANISM OF RAISING AND QUANTIFICATION OF SPECIFIC HEAT FLUX AT BOILING OF NANOFLUIDS IN FREE CONVECTION CONDITIONS

2017 ◽  
pp. 25-34
Author(s):  
V.N. Moraru
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Capacity ◽  
Specific Heat ◽  
Chemical Properties ◽  
Heating Surface ◽  
Physical Models ◽  
Superheated Liquid ◽  
Two Phase ◽  
Boiling Process

The results of our work and a number of foreign studies indicate that the sharp increase in the heat transfer parameters (specific heat flux q and heat transfer coefficient _) at the boiling of nanofluids as compared to the base liquid (water) is due not only and not so much to the increase of the thermal conductivity of the nanofluids, but an intensification of the boiling process caused by a change in the state of the heating surface, its topological and chemical properties (porosity, roughness, wettability). The latter leads to a change in the internal characteristics of the boiling process and the average temperature of the superheated liquid layer. This circumstance makes it possible, on the basis of physical models of the liquids boiling and taking into account the parameters of the surface state (temperature, pressure) and properties of the coolant (the density and heat capacity of the liquid, the specific heat of vaporization and the heat capacity of the vapor), and also the internal characteristics of the boiling of liquids, to calculate the value of specific heat flux q. In this paper, the difference in the mechanisms of heat transfer during the boiling of single-phase (water) and two-phase nanofluids has been studied and a quantitative estimate of the q values for the boiling of the nanofluid is carried out based on the internal characteristics of the boiling process. The satisfactory agreement of the calculated values with the experimental data is a confirmation that the key factor in the growth of the heat transfer intensity at the boiling of nanofluids is indeed a change in the nature and microrelief of the heating surface. Bibl. 20, Fig. 9, Tab. 2.

scholarly journals The Role of Extracellular Vesicles as Shuttles of RNA and Their Clinical Significance as Biomarkers in Hepatocellular Carcinoma

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 902
Author(s):  
Eva Costanzi ◽  
Carolina Simioni ◽  
Gabriele Varano ◽  
Cinzia Brenna ◽  
Ilaria Conti ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Extracellular Vesicles ◽  
Tumor Metastasis ◽  
Biological Processes ◽  
Rna Molecules ◽  
Expression Of Genes ◽  
Non Coding Rna ◽  
Donor Cells ◽  
Relevant Role

Extracellular vesicles (EVs) have attracted interest as mediators of intercellular communication following the discovery that EVs contain RNA molecules, including non-coding RNA (ncRNA). Growing evidence for the enrichment of peculiar RNA species in specific EV subtypes has been demonstrated. ncRNAs, transferred from donor cells to recipient cells, confer to EVs the feature to regulate the expression of genes involved in differentiation, proliferation, apoptosis, and other biological processes. These multiple actions require accuracy in the isolation of RNA content from EVs and the methodologies used play a relevant role. In liver, EVs play a crucial role in regulating cell–cell communications and several pathophysiological events in the heterogeneous liver class of cells via horizontal transfer of their cargo. This review aims to discuss the rising role of EVs and their ncRNAs content in regulating specific aspects of hepatocellular carcinoma development, including tumorigenesis, angiogenesis, and tumor metastasis. We analyze the progress in EV-ncRNAs’ potential clinical applications as important diagnostic and prognostic biomarkers for liver conditions.

scholarly journals Investigation of Pressure Oscillation and Cavitation Characteristics for Submerged Self-Resonating Waterjet

2021 ◽  
Vol 11 (15) ◽  
pp. 6972
Author(s):  
Lihua Cui ◽  
Fei Ma ◽  
Tengfei Cai
Keyword(s):  
Sudden Change ◽  
Three Dimensional ◽  
Pressure Oscillation ◽  
Experimental Tests ◽  
Low Pressure ◽  
The Self ◽  
Two Phase ◽  
Cavitation Phenomenon ◽  
Pressure Zone ◽  
Unsteady Characteristics

The cavitation phenomenon of the self-resonating waterjet for the modulation of erosion characteristics is investigated in this paper. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the unsteady characteristics of the self-resonating jet. The numerical model employs the mixture two-phase model, coupling the realizable turbulence model and Schnerr–Sauer cavitation model. Collected data from experimental tests were used to validate the model. Results of numerical simulations and experimental data frequency bands obtained by the Fast Fourier transform (FFT) method were in very good agreement. For better understanding the physical phenomena, the velocity, the pressure distributions, and the cavitation characteristics were investigated. The obtained results show that the sudden change of the flow velocity at the outlet of the nozzle leads to the forms of the low-pressure zone. When the pressure at the low-pressure zone is lower than the vapor pressure, the cavitation occurs. The flow field structure of the waterjet can be directly perceived through simulation, which can provide theoretical support for realizing the modulation of the erosion characteristics, optimizing nozzle structure.

scholarly journals The Relevance of the SH2 Domain for c-Src Functionality in Triple-Negative Breast Cancer Cells

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 462
Author(s):  
Víctor Mayoral-Varo ◽  
María Pilar Sánchez-Bailón ◽  
Annarica Calcabrini ◽  
Marta García-Hernández ◽  
Valerio Frezza ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Sh2 Domain ◽  
Model Systems ◽  
System A ◽  
Promising Therapeutic Target ◽  
Relevant Role ◽  
Inactivating Mutation

The role of Src family kinases (SFKs) in human tumors has been always associated with tyrosine kinase activity and much less attention has been given to the SH2 and SH3 adapter domains. Here, we studied the role of the c-Src-SH2 domain in triple-negative breast cancer (TNBC). To this end, SUM159PT and MDA-MB-231 human cell lines were employed as model systems. These cells conditionally expressed, under tetracycline control (Tet-On system), a c-Src variant with point-inactivating mutation of the SH2 adapter domain (R175L). The expression of this mutant reduced the self-renewal capability of the enriched population of breast cancer stem cells (BCSCs), demonstrating the importance of the SH2 adapter domain of c-Src in the mammary gland carcinogenesis. In addition, the analysis of anchorage-independent growth, proliferation, migration, and invasiveness, all processes associated with tumorigenesis, showed that the SH2 domain of c-Src plays a very relevant role in their regulation. Furthermore, the transfection of two different aptamers directed to SH2-c-Src in both SUM159PT and MDA-MB-231 cells induced inhibition of their proliferation, migration, and invasiveness, strengthening the hypothesis that this domain is highly involved in TNBC tumorigenesis. Therefore, the SH2 domain of c-Src could be a promising therapeutic target and combined treatments with inhibitors of c-Src kinase enzymatic activity may represent a new therapeutic strategy for patients with TNBC, whose prognosis is currently very negative.

scholarly journals Lights and Shadows in the Genetics of Syndromic and Non-Syndromic Hearing Loss in the Italian Population

Genes ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1237
Author(s):  
Anna Morgan ◽  
Stefania Lenarduzzi ◽  
Beatrice Spedicati ◽  
Elisabetta Cattaruzzi ◽  
Flora Maria Murru ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Disease Genes ◽  
Italian Population ◽  
Essential Information ◽  
Whole Exome ◽  
Relevant Role ◽  
Multiplex Ligation Probe Amplification ◽  
Syndromic Hearing Loss

Hearing loss (HL), both syndromic (SHL) and non-syndromic (NSHL), is the most common sensory disorder, affecting ~460 million people worldwide. More than 50% of the congenital/childhood cases are attributable to genetic causes, highlighting the importance of genetic testing in this class of disorders. Here we applied a multi-step strategy for the molecular diagnosis of HL in 125 patients, which included: (1) an accurate clinical evaluation, (2) the analysis of GJB2, GJB6, and MT-RNR1 genes, (3) the evaluation STRC-CATSPER2 and OTOA deletions via Multiplex Ligation Probe Amplification (MLPA), (4) Whole Exome Sequencing (WES) in patients negative to steps 2 and 3. Our approach led to the characterization of 50% of the NSHL cases, confirming both the relevant role of the GJB2 (20% of cases) and STRC deletions (6% of cases), and the high genetic heterogeneity of NSHL. Moreover, due to the genetic findings, 4% of apparent NSHL patients have been re-diagnosed as SHL. Finally, WES characterized 86% of SHL patients, supporting the role of already know disease-genes. Overall, our approach proved to be efficient in identifying the molecular cause of HL, providing essential information for the patients’ future management.

scholarly journals The role of renewables in the Japanese power sector: implications from the EMF35 JMIP

2021 ◽  
Vol 16 (2) ◽  
pp. 375-392 ◽  
Author(s):  
Hiroto Shiraki ◽  
Masahiro Sugiyama ◽  
Yuhji Matsuo ◽  
Ryoichi Komiyama ◽  
Shinichiro Fujimori ◽  
...  
Keyword(s):  
Emission Reduction ◽  
Nuclear Power ◽  
Renewable Energies ◽  
Model Intercomparison ◽  
Power Sector ◽  
Capital Costs ◽  
Free Hydrogen ◽  
Intercomparison Project ◽  
Policy Cost

AbstractThe Japanese power system has unique characteristics with regard to variable renewable energies (VREs), such as higher costs, lower potentials, and less flexibility with the grid connection compared to other major greenhouse-gas-emitting countries. We analyzed the role of renewable energies (REs) in the future Japanese power sector using the results from the model intercomparison project Energy Modeling Forum (EMF) 35 Japan Model Intercomparison Project (JMIP) using varying emission reduction targets and key technological conditions across scenarios. We considered the uncertainties for future capital costs of solar photovoltaics, wind turbines, and batteries in addition to the availability of nuclear and carbon dioxide capture and storage. The results show that REs supply more than 40% of electricity in most of the technology sensitivity scenarios (median 51.0%) when assuming an 80% emission reduction in 2050. The results (excluding scenarios that assume the continuous growth of nuclear power and/or the abundant availability of domestic biomass and carbon-free hydrogen) show that the median VRE shares reach 52.2% in 2050 in the 80% emission reduction scenario. On the contrary, the availability of newly constructed nuclear power, affordable biomass, and carbon-free hydrogen can reduce dependence on VREs to less than 20%. The policy costs were much more sensitive to the capital costs and resource potential of VREs than the battery cost uncertainties. Specifically, while the doubled capital costs of VRE resulted in a 13.0% (inter-model median) increase in the policy cost, the halved capital costs of VREs reduced 8.7% (inter-model median) of the total policy cost. These results imply that lowering the capital costs of VREs would be effective in achieving a long-term emission reduction target considering the current high Japanese VRE costs.

scholarly journals Novel Insights on the Role of Nitric Oxide in the Ovary: A Review of the Literature

2021 ◽  
Vol 18 (3) ◽  
pp. 980
Author(s):  
Maria Cristina Budani ◽  
Gian Mario Tiboni
Keyword(s):  
Nitric Oxide ◽  
In Vivo Studies ◽  
Published Data ◽  
Vitro Fertilization ◽  
Peripheral Neurons ◽  
Relevant Role ◽  
Oocyte Meiotic Maturation

Nitric oxide (NO) is formed during the oxidation of L-arginine to L-citrulline by the action of multiple isoenzymes of NO synthase (NOS): neuronal NOS (nNOS), endotelial NOS (eNOS), and inducible NOS (iNOS). NO plays a relevant role in the vascular endothelium, in central and peripheral neurons, and in immunity and inflammatory systems. In addition, several authors showed a consistent contribution of NO to different aspects of the reproductive physiology. The aim of the present review is to analyse the published data on the role of NO within the ovary. It has been demonstrated that the multiple isoenzymes of NOS are expressed and localized in the ovary of different species. More to the point, a consistent role was ascribed to NO in the processes of steroidogenesis, folliculogenesis, and oocyte meiotic maturation in in vitro and in vivo studies using animal models. Unfortunately, there are few nitric oxide data for humans; there are preliminary data on the implication of nitric oxide for oocyte/embryo quality and in-vitro fertilization/embryo transfer (IVF/ET) parameters. NO plays a remarkable role in the ovary, but more investigation is needed, in particular in the context of human ovarian physiology.

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