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Herranz G.,Levenfeld B.,Varez A. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
In this present investigation, Metal Injection Moulding (MIM) of M2 High Speed Steel (HSS) parts using a wax-High Density Polyethylene (HDPE) binder is shown. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding was performed between 450 and . The specimens were sintered at temperatures between 1210 and in high vacuum atmosphere, obtaining the 98% of the theoretical density. In the samples with higher residual carbon content, the sintering window was extended up to 20 degrees and the optimum temperature was lower.
OECD/NEA Sandia Fuel Project phase I: Benchmark of the ignition testing
Adorni, M.,Herranz, L.E.,Hollands, T.,Ahn, K.I.,Bals, C.,D'Auria, F.,Horvath, G.L.,Jaeckel, B.S.,Kim, H.C.,Lee, J.J.,Ogino, M.,Techy, Z.,Velazquez-Lozad, A.,Zigh, A.,Rehacek, R. North-Holland Pub. Co 2016 Nuclear engineering and design Vol.307 No.-
The OECD/NEA Sandia Fuel Project provided unique thermal-hydraulic experimental data associated with Spent Fuel Pool (SFP) complete drain down. The study conducted at Sandia National Laboratories (SNL) was successfully completed (July 2009 to February 2013). The accident conditions of interest for the SFP were simulated in a full scale prototypic fashion (electrically heated, prototypic assemblies in a prototypic SFP rack) so that the experimental results closely represent actual fuel assembly responses. A major impetus for this work was to facilitate severe accident code validation and to reduce modeling uncertainties within the codes. Phase I focused on axial heating and burn propagation in a single PWR 17x17 assembly (i.e. ''hot neighbors'' configuration). Phase II addressed axial and radial heating and zirconium fire propagation including effects of fuel rod ballooning in a 1x4 assembly configuration (i.e. single, hot center assembly and four, ''cooler neighbors''). This paper summarizes the comparative analysis regarding the final destructive ignition test of the phase I of the project. The objective of the benchmark is to evaluate and compare the predictive capabilities of computer codes concerning the ignition testing of PWR fuel assemblies. Nine institutions from eight different countries were involved in the benchmark calculations. The time to ignition and the maximum temperature are adequately captured by the calculations. It is believed that the benchmark constitutes an enlargement of the validation range for the codes to the conditions tested, thus enhancing the code applicability to other fuel assembly designs and configurations. The comparison of lumped parameter and CFD computer codes represents a further valuable achievement.
Amgarou, Khalil,Herranz, Margarita Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11
This paper reports on the state-of-the-art of the main non-destructive assay (NDA) techniques usually used for in-situ radiological characterization of nuclear facilities subject to a decommissioning programme. For the sake of clarity and coherence, they have been classified as environmental radiation monitoring, surface contamination measurements, gamma spectrometry, passive neutron counting and radiation cameras. Particular mention is also made here to the various challenges that each of these techniques must currently overcome, together with the formulation of some proposals for a potential evolution in the future.
Propagation of Nuclear Data Uncertainties in Transmutation Calculations Using ACAB Code
O. Cabellos,N. Garcia-Herranz,Carlos J. Diez de la Obra,R. Alvarez-Cascos,J. Sanz,F. Ogando,P. Sauvan 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The assessment of the accuracy of parameters related to the reactor core performance (e.g. keff) and fuel cycle (e.g. isotopic evolution/transmutation) due to the uncertainties in the basic nuclear data (ND) is a critical issue. Different error propagation techniques (adjoint/forward sensitivity analysis procedures and/or Monte Carlo technique) can be used to address by computational simulation the systematic propagation of uncertainties on the final parameters. To perform this uncertainty assessment, the ENDF covariance files (variance/correlation in energy and cross-reactions-isotopes correlations) are required.In this paper, we assess the impact of ND uncertainties on the isotopic prediction for a conceptual design of a modular European Facility for Industrial Transmutation (EFIT) for a discharge burnup of 150 GWd/tHM. The complete set of uncertainty data for cross sections (EAF2007/UN, SCALE6.0/COVA-44G), radioactive decay and fission yield data (JEFF-3.1.1) are processed and used in ACAB code.
Use of similarity indexes to identify spatial correlations of sodium void reactivity coefficients
Jimenez-Carrascosa, Antonio,Garcia-Herranz, Nuria Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11
The safety level of Sodium Fast Reactors is directly related with the sodium void reactivity. A low-void effect design has been proposed within the Horizon2020 ESFR-SMART project thanks to the introduction of a sodium plenum above the active core. In order to assess the impact of this core conception on transient analysis, a map with the spatial distribution of sodium void worth can be computed and fed into a point-kinetics-based transient code. Due to the spatial correlations between neighboring zones, the global effect of voiding two different axial or radial regions is not necessarily the sum of both individual contributions. Neglecting those correlations in the void worth map and consequently in the transient analysis may lead to an unrealistic prediction of the transient sequences. In this work, a method based on sensitivity analysis and similarity assessment is proposed for predicting those correlations. The method proved to be able to establish correlations between axial slices of a sub-assembly and was checked against realistic sodium void propagation patterns.
Matula G.,Dobrzanski L.A.,Kloc A.,Herranz G.,Varez A.,Levenfeld B.,Torralba J.M. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Based on the comparison of structures and properties of the HS6-5-2 high speed steels made with the powder injection moulding method, pressureless forming, compacting and sintering, and commercial steels made with the ASEA-STORA method, fine carbides spread evenly in the steel matrix were found in the structure of all tested high-speed steels in the sintered state. The steels made with the pressureless forming method are characteristic of the lowest sintering temperature and the highest density, resulting from the high carbon concentration coming from the binding agent degradation.
Sintering of Mechanically Alloyed YSZ Nanocrystalline Powders
De la Torre,M. A. Lopez,Dura O. J.,Hernandez M.,Garcia-Cordobes M.,Herranz G.,Sanchez-Bautista C.,Rodriguez G. P. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
We report on the mechanical and structural properties of nanocrystalline 8% and 10% mol yttria stabilized zirconia (YSZ) obtained using mechanical alloying (MA). The as-milled powders show a body-centered cubic structure with grain sizes in the nanometer scale. After uniaxial pressing and sintering the compacts exhibit good mechanical properties. We discuss the correlation of these enhanced properties with the microstructural changes induced by heat treatment.