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- Moreau, V., et al.
(författare)
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Pool CFD modelling : lessons from the SESAME project
- 2019
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Ingår i: Nuclear Engineering and Design. - : ELSEVIER SCIENCE SA. - 0029-5493 .- 1872-759X. ; 355
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Tidskriftsartikel (refereegranskat)abstract
- The current paper describes the Computational Fluid-Dynamics (CFD) modelling of Heavy Liquid Metal (HLM) flows in a pool configuration and in particular how this is approached within the Horizon 2020 SESAME project. SESAME's work package structure, based on a systematic approach of redundancy and diversification, is explained along with its motivation. The main achievements obtained and the main lessons learned during the project are illustrated. The paper focuses on the strong coupling between the experimental activities and CFD simulations performed within the SESAME project. Two different HLM fluids are investigated: pure lead and Lead-Bismuth Eutectic. The objective is to make CFD a valid instrument used during the design of safe and innovative Gen-IV nuclear plants. Some effort has also been devoted to Proper Orthogonal Decomposition with Galerkin projection modelling (POD-Galerkin), a reduced order model suited for Uncertainty Quantification that operates by post-processing CFD results. Assessment of Uncertainty highly improves the reliability of CFD simulations. Dedicated experimental campaigns on heavily instrumented facilities have been conceived with the specific objective to build a series of datasets suited for the calibration and validation of the CFD modelling. In pool configuration, the attention is focused on the balance between conductive and convective heat transfer phenomena, on transient test-cases representative of incidental scenarios and on the possible occurrence of solidification phenomena. Four test sections have been selected to generate the datasets: (i) the CIRCE facility from ENEA, (ii) the TALL-3D pool test section from KTH, (iii) the TALL-3D Solidification Test Section (STS) from KTH and (iv) the SESAME Stand facility from CVR. While CIRCE and TALL-3D were existing facilities, the STS and SESAME Stand facility have been conceived, built and operated within the project, heavily relying on the use of CFD support. Care has been taken to ensure that almost all tasks were performed by at least two partners. Specific examples are given on how this strategy has allowed to uncover flaws and overcome pitfalls. Furthermore, an overview of the performed work and the achieved results is presented, as well as remaining or new uncovered issues. Finally, the paper is concluded with a description of one of the main goals of the SESAME project: the construction of the Gen-IV ALFRED CFD model and an investigation of its general circulation.
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| 4. |
- Permyakov, Eugene A, et al.
(författare)
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Ultraviolet illumination-induced reduction of alpha-lactalbumin disulfide bridges
- 2003
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Ingår i: Proteins: Structure, Function, and Bioinformatics. - : Wiley. - 0887-3585. ; 51:4, s. 498-503
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged exposure of Ca2+-loaded or Ca2+-depleted human -lactalbumin to ultraviolet light (270-290 nm, 1 mW/cm2, for 2 to 4 h) results in a 10-nm red shift of its tryptophan fluorescence spectrum. Gel chromatography of the UV-illuminated samples reveals two non-native protein forms: (1) a component with a red-shifted tryptophan fluorescence spectrum; and (2) a component with kynurenine-like fluorescent properties. The first component has from 0.6 to 0.9 free DTNB-reactive SH groups per protein molecule, which are absent in the native protein and is characterized by slightly lowered Ca2+-affinity (2 × 108 M-1 versus 8 × 108 M-1 for the native protein) and absence of observable thermal transition. The second component corresponds to the protein with photochemically modified tryptophan residues. It is assumed that the UV excitation of tryptophan residue(s) in -lactalbumin is followed by a transfer of electrons to the SS bonds, resulting in their reduction. Mass spectrometry data obtained for trypsin-fragmented UV-illuminated -lactalbumin with acrylodan-modified free thiol groups reveal the reduction of the 61-77 and 73-91 disulfide bridges. The effect observed has to be taken into account in any UV-region spectral studies of -lactalbumin. Proteins 2003;51:498-503.
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| 5. |
- Suikkanen, H., et al.
(författare)
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Thermal Hydraulic Experiments and Code Validation for LWR SMRs within the European McSAFER Project: Overview of Activities and Current Status
- 2023
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Ingår i: Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023. - : American Nuclear Society. ; , s. 2388-2401
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Konferensbidrag (refereegranskat)abstract
- The EU Horizon 2020 project McSAFER was launched in 2020 to advance the safety research of small modular reactors (SMR) via thermal-hydraulic experiments with related code validation and numerical coupled multi-physics and multi-scale simulations. This paper provides an overview of the thermal-hydraulic experiments and code validation within the project and presents the status of these activities highlighting some of the results already obtained. Experiments are performed at three European laboratories with test facilities dedicated for the investigation of SMR-relevant phenomena. Fundamental heat transfer experiments with boiling up to critical heat flux under forced convection for rod configurations and conditions representative of SMRs are performed with the COSMOS-H facility. Performance of the helical coil steam generator, core cross flow phenomena and the general behavior of an SMR operating with natural circulation are investigated with the MOTEL facility. Heat transfer phenomena are investigated in conditions relevant for SMRs also in forced to natural circulation transients with the HWAT facility. Selected thermal hydraulic system, subchannel and computational fluid dynamics (CFD) codes are validated with the experimental data.
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| 6. |
- Udalov, Yurii, et al.
(författare)
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Coordination Nature of Phase Separation in Oxide Melts
- 2013
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Ingår i: Glass Physics and Chemistry. - 1087-6596 .- 1608-313X. ; 39:4, s. 431-443
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Tidskriftsartikel (refereegranskat)abstract
- The behavior of uranium oxide-silica, zirconia-alumina, zirconia-iron oxide, uranium oxideiron oxide, zirconia-alumina-iron oxide, and uranium oxide-iron oxide-zirconia melts was experimentally investigated in the air. The existence of two-phase fluids in these systems was confirmed. It is proposed that the reason for the phase separation is the formation of complexes with the general formula x[M3+O8/2] [Me4+O8/2]. The influence of a complex concentration on the density and surface tension of melts in the ZrO2-Al2O3 system was demonstrated.
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