A New Coupled CFD/Neutron Kinetics System for High Fidelity Simulations of LWR Core Phenomena: Proof of Concept

The Institute for Neutron Physics and Reactor Technology (INR) at the Karlsruhe Institute of Technology (KIT) is investigating the application of the meso- and microscale analysis for the prediction of local safety parameters for light water reactors (LWR). By applying codes like CFD (computational fluid dynamics) and SP3 (simplified transport) reactor dynamics it is possible to describe the underlying phenomena in a more accurate manner than by the nodal/coarse 1D thermal hydraulic coupled codes. By coupling the transport (SP3) based neutron kinetics (NK) code DYN3D with NEPTUNE-CFD, within a parallel MPI-environment, the NHESDYN platform is created. The newly developed system will allow high fidelity simulations of LWR fuel assemblies and cores. In NHESDYN, a heat conduction solver, SYRTHES, is coupled to NEPTUNE-CFD. The driver module of NHESDYN controls the sequence of execution of the solvers as well as the communication between the solvers based on MPI. In this paper, the main features of NHESDYN are discussed and the proof of the concept is done by solving a single pin problem. The prediction capability of NHESDYN is demonstrated by a code-to-code comparison with the DYNSUB code. Finally, the future developments and validation efforts are highlighted

Multifunctional smart coatings on novel ceramics and glassceramic substrates in the context of the circular economy

Nowadays is time of products generated by “smart coatings” that exhibit multiple functionalities. In particular, the construction industry is reached the point where it is possible to fabricate “smart and sustainable” buildings that fulfll the requirements of a growing marketplace of products and devices for “smart cities” generation. In addition, if the buildings are “green”, i.e. in accordance with the today‘s economic model “made to be made again” or so-called “circular economy” they are very attractive and viable alternative for future businesses and industrial exploring. In this concept, we report a development sustainable ceramic and glass-ceramic tile substrates made by cheap, easily accessible and recycled materials that are further functionalized by different “smart coatings” for specifc applications. Devices that generate and save energy, air and pollution cleaning, with anti-slip and phosphorescence properties are some examples of the overview that this publication described

Incorporación de residuos derivados de la fabricación cerámica y del vidrio reciclado en el proceso cerámico integral

The following research work shows the results of the introduction of waste generated by the ceramic industry, such as the calcined clay from fired porcelain of stoneware and raw biscuit, sludge and cleaning water, as well as waste from other sectors like the recycling glass. In this way, it can be obtained a stoneware porcelain slab, engobe-glaze and satin glaze that contains high percentage of recyclable raw material

Accelerating urban scale simulations leveraging local spatial 3D structure

[EN] This paper presents a hybrid methodology for accelerating Computational Fluid Dynamics (CFD) simulations intertwining inferences from deep neural networks (DNN). The strategy leverages the local spatial data of the velocity field to leverage three-dimensional convolutional kernels within DNN. The hybrid workflow is composed of two-step cycles where CFD solvers calculations are utilized to feed predictive models, whose inferences, in turn, accelerate the simulation of the fluid evolution compared with traditional CFD. This approach has proved to reduce 30% time-to-solution in an urban scale study case, which leads to generating massive datasets at a fraction of the cost.Researcher S. Iserte was supported by postdoctoral fellowship APOSTD/2020/026 from GVA-ESF. While researcher A. Macias was supported by predoctoral fellowship FDGENT from GVA. CTE-Power cluster of the Barcelona Supercomputing Center, and Tirant III cluster of the Servei d'Informatica of the University of Valencia were leveraged in this research. Authors want to thank the anonymous reviewers whose suggestions significantly improved the quality of this manuscript.Iserte, S.; Macías, A.; Martínez-Cuenca, R.; Chiva, S.; Paredes Palacios, R.; Quintana-Ortí, ES. (2022). Accelerating urban scale simulations leveraging local spatial 3D structure. Journal of Computational Science. 62:1-11. https://doi.org/10.1016/j.jocs.2022.1017411116

Trebouxia lynnae sp. nov. (former Trebouxia sp. TR9): biology and biogeography of an epitome lichen symbiotic microalga

Two microalgal species, Trebouxia jamesii and Trebouxia sp. TR9, were detected as the main photobionts coexisting in the thalli of the lichen Ramalina farinacea. Trebouxia sp. TR9 emerged as anew taxon in lichen symbioses and was successfully isolated and propagated in in vitro culture andthoroughly investigated. Several years of research have confirmed the taxon Trebouxia sp. TR9 tobe a model/reference organism for studying mycobiont–photobiont association patterns in lichensymbioses. Trebouxia sp. TR9 is the first symbiotic, lichen-forming microalga for which an exhaustivecharacterization of cellular ultrastructure, physiological traits, genetic and genomic diversity is available.The cellular ultrastructure was studied by light, electron and confocal microscopy; physiologicaltraits were studied as responses to different abiotic stresses. The genetic diversity was previouslyanalyzed at both the nuclear and organelle levels by using chloroplast, mitochondrial, and nucleargenome data, and a multiplicity of phylogenetic analyses were carried out to study its intraspecificdiversity at a biogeographical level and its specificity association patterns with the mycobiont.Here, Trebouxia sp. TR9 is formally described by applying an integrative taxonomic approach and ispresented to science as Trebouxia lynnae, in honor of Lynn Margulis, who was the primary modernproponent for the significance of symbiosis in evolution. The complete set of analyses that werecarried out for its characterization is provided

Modeling hydrodynamics and biochemical reactions in a Flat Plate Bioreactor

Modeling the complex interactions between biochemical reactions and hydrodynamics is the key to optimize biofiltration systems performance. In this work, biological kinetics expressions were implemented into Computational Fluid Dynamics (CFD) model as transport equations, including convective and diffusive terms. Previously, activity within the biofilm of a flat plate bioreactor (FPB) was experimentally investigated measuring dissolved oxygen (DO) profiles by means of microsensors and under common operating conditions. Moreover, a mathematical model to describe mass transport and metabolic activity in the FPB was developed and their parameters were fitted from experimental results. Then, a CFD model, combining hydrodynamics and biochemical reactions, was developed and solved to simulate local transient flow and dynamic behaviors of biofilm growth and substrate (glucose) biodregradation in the FPB. The CFD simulation results were evaluated by studying hydrodynamics characterization in the FPB and comparing simulated DO profiles with experimental DO profiles within the biofilm section. The hydraulic behaviour corresponds to a laminar flow and simulated DO profiles illustrate a satisfactory agreement with experimental data for different biofilm densities. Glucose and oxygen biodegradation and biomass growth along the bioreactor were described using the CFD model.Peer ReviewedPostprint (published version

Rheological properties of biofilms: steady and transient shear flow modeling

Premi al millor poster en la 7th Internacional Conference on Biotechniques for Air Pollution Control and BioenergyPeer ReviewedAward-winningPostprint (published version

On the One-Dimensional Modeling of Vertical Upward Bubbly Flow

[EN] The one-dimensional two-fluid model approach has been traditionally used in thermal-hydraulics codes for the analysis of transients and accidents in water¿cooled nuclear power plants. This paper investigates the performance of RELAP5/MOD3 predicting vertical upward bubbly flow at low velocity conditions. For bubbly flow and vertical pipes, this code applies the drift- velocity approach, showing important discrepancies with the experiments compared. Then, we use a classical formulation of the drag coefficient approach to evaluate the performance of both approaches. This is based on the critical Weber criteria and includes several assumptions for the calculation of the interfacial area and bubble size that are evaluated in this work. A more accurate drag coefficient approach is proposed and implemented in RELAP5/MOD3. Instead of using the Weber criteria, the bubble size distribution is directly considered. This allows the calculation of the interfacial area directly from the definition of Sauter mean diameter of a distribution. The results show that only the proposed approach was able to predict all the flow characteristics, in particular the bubble size and interfacial area concentration. Finally, the computational results are analyzed and validated with cross-section area average measurements of void fraction, dispersed phase velocity, bubble size, and interfacial area concentration.The authors sincerely thank the Plan Nacional de I+D+i for funding the Projects MODEXFLAT ENE2013-48565-C2-1- P, ENE2013-48565-C2-2-P, and NUC-MULTPHYS ENE2012- 34585.Peña-Monferrer, C.; Gómez-Zarzuela, C.; Chiva, S.; Miró Herrero, R.; Verdú Martín, GJ.; Muñoz-Cobo, JL. (2018). On the One-Dimensional Modeling of Vertical Upward Bubbly Flow. Science and Technology of Nuclear Installations. 2018:1-10. https://doi.org/10.1155/2018/2153019S110201

Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows

[EN] For more than fifty years, hundreds of research works have focused on the study of annular flow because of its huge importance in many industrial processes, for instance, chemical, petroleum, etc., being of particular interest in nuclear industry. Specifically, interfacial waves play a vital role in the mass, momentum and energy transference processes between gas and liquid phases. This paper describes the new experimental measurements of vertical upward co-current two-phase gas-liquid flow carried out in a tube with an inner diameter of 44 mm. The liquid film thickness and the major characteristics of the interfacial waves have been measured using a non-intrusive instrument, a conductance probe. The physical phenomenon in which this device is based is the change in the electrical conductivity between air and water, i.e., the electrical signal collected in the sensor receiver depends on the thickness of the liquid film layer. The experimental measurements range from 2000 to 3500 l/min for the gas volumetric flow rate, and from 4 to 10 l/min for the liquid volumetric flow rate. Correlation of the experimental measurements of liquid film thickness and the major properties of the interfacial waves have been analyzed using non-dimensional numbers. An important part of the document focuses on the comparison of the experimental data and the fitting correlations against several of the most widely used expressions. Throughout this paper, in addition to present all the available correlations, the existing scattering found when comparing against other expressions have been also confirmed, underlining the existence of gaps of knowledge even today. Emphasize that the proposed correlations are the ones that better fit the data of all experimental series carried out under the present study for the analyzed variables, with almost all the experimental points covered by the +/- 10% error bands of the new correlations.The authors are indebted to the plan of I+D support of the EXMOTRANSIN project ENE2016-79489-C2-1-P.Cuadros-Orón, JL.; Rivera-Durán, Y.; Berna, C.; Escrivá, A.; Muñoz-Cobo, JL.; Monrós-Andreu, G.; Chiva, S. (2019). Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows. Nuclear Engineering and Design. 346:112-130. https://doi.org/10.1016/j.nucengdes.2019.03.008S11213034

High adherence to the nordic diet is associated with lower levels of total and platelet-derived circulating microvesicles in a norwegian population

Circulating microvesicles (cMV) are small phospholipid-rich blebs shed from the membrane of activated vascular cells that contribute to vascular disease progression. We aimed to investigate whether the quality of the Nordic diet is associated with the degree of blood and vascular cell activation measured by MV shedding in elderly patients after an acute myocardial infarction (AMI). One-hundred and seventy-four patients aged 70-82 years were included in this cross-sectional study. Fasting blood samples were taken within 2 to 8 weeks after an AMI. Annexin V (AV) cMV derived from blood and vascular cells were measured through flow cytometry. A patient's usual diet was recorded with the SmartDiet® questionnaire. Patients with higher adherence to the Nordic diet (highest diet score) had lower levels of total AV and platelet-derived (CD61/AV and CD31/AV) cMV. Dietary habits influence cellular activation. A high adherence to the Nordic diet (assessed by the SmartDiet® score) in elderly post-AMI patients was associated with lower levels of platelet activation, which was reflected by a lesser release of MV carrying platelet-derived epitopes, potentially contributing to an explanation of the cardioprotective effects of the Nordic diet