10 research outputs found
Slow-time phase-coded Tx multiplexing and online calibration for FMCW automotive radar systems
No full textAuthor Mayeul JeanninDissertation Johannes Kepler Universität Linz 202
Sintering of MOX fuels : Influence of fabrication conditions and oxygen partial pressure
No full textLes phénomènes de diffusion se produisant lors du frittage des oxydes mixtes d’uranium et de plutonium (MOX) dépendent du potentiel d’oxygène de l’atmosphère du four. L’atmosphère et la température engendrent des écarts à la stœchiométrie oxygène, appelée rapport O/M, dans l’oxyde mixte U1-yPuyO2±x. Ces travaux de thèse ont porté sur une meilleure connaissance de l’évolution du rapport O/M et de la microstructure des céramiques en fonction de la composition du mélange UO2/PuO2/(UPu)O2 et du potentiel d’oxygène au cours du frittage. Leurs effets sur la densification et les microstructures ont été étudiés, ce qui a permis de proposer la mise œuvre d’une poudre de solution solide (UPu)O2 obtenue par coprécipitation oxalique.Un suivi innovant de la PO2 a été conçu par un asservissement et des mesures entrée / sortie des fours par des pompes oxygène et sondes zircone. Ainsi, le rapport O/M a pu être suivi quantitativement tout au long d’un cycle de frittage. Il permet une bien meilleure compréhension des échanges d’oxygène en température entre l’échantillon et l’atmosphère. Un écart important entre les prévisions des calculs thermodynamiques et les données expérimentales est observé, même après plusieurs heures à 1700°C, écart particulièrement sensible à la formation de la solution solide (UPu)O2 ainsi qu’aux échanges locaux solide/gaz. Un schéma réactionnel de variation du rapport O/M au cours du temps, en faisant volontairement varier la PO2 du gaz a permis d’orienter les cycles de frittage pour obtenir la microstructure et le rapport final O/M souhaités.Ces nouvelles connaissances serviront de données d’entrée pour la modélisation de l’étape de frittage et ainsi de nouveaux cycles de frittage en rupture en four batch ou en four continu sont envisagés. Ils permettent d’obtenir de nouveaux produits et/ou des gains procédés. Ces avantages peuvent être couplés par l’apport bénéfique de la présence de solution solide (UPu)O2 en tant que nouvelle matière première.Diffusion phenomena occurring during the sintering of mixed uranium and plutonium oxides (MOX) depend on the oxygen potential of the furnace atmosphere. The atmosphere and the temperature generate deviations from the oxygen stoichiometry, called O/M ratio, in the mixed oxide U1-yPuyO2±x. The PhD work focused on a better understanding of the evolution of the O/M ratio and the ceramic microstructure as a function of the composition of the UO2 / PuO2 / (UPu)O2 mixture and of the oxygen potential during sintering. Their effects on densification and microstructures have been studied and have led to proposing the implementation of a (UPu)O2 solid solution powder obtained by oxalic coprecipitation.An innovative monitoring of PO2 has been designed by stabilizing and controlling O2 input/output measurements of the ovens by oxygen pumps and zirconia probes. It allows a much better understanding of the oxygen exchanges in temperatures between the sample and the atmosphere. A significant difference between the thermodynamic calculations and experimental data is observed, even after several hours at 1700°C. The kinetic effects are particularly sensitives to the formation of the (UPu)O2 solid solution as well as to local solid/gas exchanges. A reaction scheme for varying the O/M ratio over time, by voluntarily varying the PO2 of the input gas makes it possible to design sintering cycles in order to obtain the desired microstructure and final O/M ratio.This new knowledge will be used as input data for the modelling of the sintering step. New sintering cycles in batch oven or in continuous oven could then be considered. They make possible to obtain new products and / or process gains. These advantages can be coupled with the beneficial contribution of the presence of a solid solution as a new raw material
Progress in evaluating a possible electromagnetic interaction energy in a gravitational field
No full text13 pages. Text of a talk given at the 14th Conf. on Classical and Quantum Relativistic Dynamics of Particles and Fields (IARD 2024: Helsinki, June 3-6, 2024). N.B.: the published version has 7 references less: some quotations of previous work by the author replaced by "see Ref. [N] and references therein".International audienceThe Lorentz-Poincaré interpretation of special relativity (SR) keeps the classical concepts of separated space and time, at the price of postulating an indetectable preferred inertial frame or "ether". But SR does not contain gravity. The presence of gravity could make the ether detectable. This is one idea behind the "scalar ether theory of gravitation" (SET), which coincides with SR if the gravity field vanishes, and passes a number of tests. However, the coupling of SET with the Maxwell electromagnetic (EM) field needs to use the theory's dynamical equation for the energy tensor in a non-trivial way. It cannot be assumed that the energy tensors of the charged matter and the EM field add to give the total energy tensor,source of the gravitational field. Thus, an additional, "interaction" energy tensor T_inter has to be postulated. Asking that T_inter is Lorentz-invariant in the situation of SR, fixes its form. It depends only on a scalar field p. T_inter is an exotic kind of matter and is distributed in the whole space, hence it could contribute to dark matter. For a weak gravitational field, p obeys a first-order partial differential equation (PDE) involving the EM field and the Newtonian potential. However, the EM field varies on the scale of the wavelength, which is extremely small. To get the field p in a galaxy, some averaging has to be done. After several attempts based on the homogenization theory, a simpler way has been found recently: If the macro-averages of p and the EM field vary smoothly, it can be shown that the PDE for p remains valid in the same form with spacetime-averaged fields. The current stage of calculations will also been shown
Conceptual design of ASTRID fuel sub-assemblies
No full textInternational audienceThe French 600 MWe Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID) project has reached the end of its Conceptual Design phase. The core design studies are being conducted by the CEA with support from AREVA and EDF. Innovative design choices for the core have been made to comply with the GEN IV reactor objectives, marking a break with the former Phénix and SuperPhénix Sodium Fast Reactors. The main objective to improve safety compared with current GEN II or III reactors led to a core design that demonstrates intrinsically safe behaviour. A negative sodium void worth is achieved thanks to a new fuel sub-assembly design including (U,Pu)O and UO axially heterogeneous fuel pins, a large cladding/small spacer wire bundle, a sodium plenum above the fuel pins, and upper neutron shielding with both enriched and natural boron carbide (BC) which also maintain a low secondary sodium activity level. As these Na-bonded BC pins can lead to the retention of unacceptable amounts of sodium, the whole upper neutron shielding has been made removable on-line through the sub-assembly head just before the washing operations. Finite elements calculations have been performed to increase the stiffness of the stamped spacer pads in order to analyse its effect on the core mechanical behaviour during hypothetical radial core flowering and compaction events. More generally, all design choices for ASTRID have been made with the permanent objective of minimising the sub-assembly height to decrease the overall costs of the boiler reactor and the fuel cycle. This paper describes the fuel sub-assembly design for the ASTRID CFV v4 core at the end of the Conceptual Design phase (AVP2). Focus is placed on innovations and specificities in the design compared with former French SFRs
Les réacteurs HTR et leur combustible - Le programme ANTARES
No full textLe projet d’AREVA NP de réacteur modulaire HTR destiné à produire de l’électricité et/ou de la chaleur industrielle à haute température (programme ANTARES) est développé en utilisant au mieux les caractéristiques de sûreté intrinsèques spécifi ques à ce type de réacteur dans le respect des principes de sûreté universellement reconnus. Cette approche est rendue possible grâce aux performances xceptionnelles des particules ombustibles dont l’expérience passée a démontré le bon comportement (rejets radiologiques très faibles) non seulement en fonctionnement normal mais aussi dans les situations accidentelles. La démarche engagée par AREVA NP et le CEA consiste à développer des fabrications de haute qualité et des contrôles renforcés et automatisés de la qualité effective, à confi rmer expérimentalement les performances du combustible ainsi obtenu, à développer un code de calcul modélisant le comportement de ce combustible en fonctionnement normal et accidentel sur la base d’une compréhension approfondie des phénomènes en jeu, à qualifi er ce code et à optimiser si nécessaire la conception du combustible pour atteindre les performances visées pour ANTARES. Enfi n, afi n de se conformer aux objectifs de développement durable, des solutions seront développées pour maîtriser la gestion des déchets combustibles spécifi ques de cette fi lière et minimiser leur fl ux autant que faire se peut
The results of the irradiation experiment MARIOS on americium transmutation
No full textThe MARIOS irradiation experiment is the latest in a series of experiments on americium transmutation, and has been carried out in the framework of EURATOM’s 7th Framework Programme (FP7) project FAIRFUELS, which started the 1st January 2009 and is still ongoing. The Post Irradiation Examination (PIE) of MARIOS samples will be performed under the PELGRIMM project. The transmutation of Minor Actinides (MA) is a fundamental step in order to be able to close the nuclear fuel cycle. One of the attractive possibilities to burn MA, is represented by the Minor Actinides Bearing Blanket (MABB) concept. In this option, MA are diluted in a UO2 matrix and irradiated for a long time (from 2000 to 4100 days) in radial blankets at the periphery of the outer core of a Sodium Fast Reactor (SFR). Past experimental activities in the field of transmutation and testing of innovative nuclear fuel containing Am has proved that the release or trapping of helium as well as the studies on the swelling of such kind of fuel is a key issue for its safety design. Therefore, the main objective of the MARIOS experiment is the study of the in-pile behaviour of UO2 (with natural uranium) containing Am as minor actinide in order to gain knowledge on the role of the microstructure and of the temperature on the gas release and on fuel swelling for the MABB concept.
The MARIOS irradiation experiment started on the 19th of March 2011 and finished on the 2nd of May 2012 after 11 reactor cycles (304 full power days) in the HFR (High Flux Reactor) in Petten (The Netherlands).
The MARIOS irradiation experiment will determine the performance of the MABB fuel, the behaviour of such targets during the irradiation did not show any anomalies. It is possible to conclude that from an operational point of view, these kinds of fuel which have been developed mainly having in mind the possibility to burn MA in a blanket at the periphery of a Sodium Fast Reactor, did not show significant issues. This paper summarises the main experimental data obtained after the 11-cycle irradiation of the MARIOS experiment in the HFR.JRC.F.4 - Nuclear Reactor Integrity Assessment and Knowledge Managemen
High-Temperature Reactor Fuel Technology in the European Projects HTR-F1 and RAPHAEL
No full textIn April 2005, a new 4-year Integrated Project on Very High Temperature Reactors (RAPHAEL: ReActor for Process Heat And ELectricity) was started as part of
EURATOM’s 6th Framework Programme. The Sub-Project on Fuel Technology (SP-FT) is one of eight sub-projects in RAPHAEL, with 8 partners from industry, R&D
organizations and a nuclear-safety expertise organization: CEA, FZ Jülich, JRC, Nexia Solutions, AREVA-NP, NRG, Belgonucléaire and IRSN. While the earlier HTR-F and
HTR-F1 projects aimed at re-mastering fuel fabrication technology, testing existing state-of-the-art HTR fuels at high burn-up and high temperature and understanding fuel behavior), the R&D conducted in RAPHAEL SP-FT focuses on understanding fuel behavior and determining the limits of state-of-the-art fuel as well as on potential further Fabrication processes will be developed for an
alternative kernel composition (UCO), with a potential for
decreasing the CO pressure built-up in the particle, and for an
alternative coating layer (ZrC), which remains more stable at
higher temperature than SiC, thus providing increased
Post-irradiation examinations and heat-up tests
performed on irradiated fuel will allow investigation of the
behavior of state-of-the-art fuel in a VHTR’s normal and
accidental conditions.
Based on the fuel particle models established in FP5,
the fuel modeling capabilities will be improved:
An irradiation will be performed in the HFR Petten for
measuring the changes in coating material properties as a
function of fluence and temperature, with samples
coming from the new fabrication process. This will
allow introduction of particle behavior models for
coatings which are not only more accurate than those
presently based on old data, but also more relevant to
present materials.
Fission-product release modeling and statistical methods
will be developed to integrate the individual behavior of
thousands of particles within fuel elements.
Code benchmarking, started in FP5, will be continued
with the acquisition of new experimental data.
This paper presents progress in RAPHAEL SP-FT as
well as the remaining activities of the earlier HTR-F1 project.JRC.F.3 - High Flux and Future Reactor
Data and code from: Loggerhead turtle oceanic-neritic habitat shift reveals key foraging areas in the Western Indian Ocean
No full textData and code from: Loggerhead turtle oceanic-neritic habitat shift reveals key foraging areas in the Western Indian Ocean
Authors: Jonathan R. Monsinjon, Antoine Laforge, Philippe Gaspar, Anne Barat, Olivier Bousquet, Stéphane Ciccione, Claire Jean, Katia Ballorain, Mayeul Dalleau, Rui Coelho, Sylvain Bonhommeau, Jérôme Bourjea
Correspondence: [email protected]
1. R code (run with R version 4.1.0) used to interpolate raw locations at regular 12-h time step:
# Author
Antoine Laforge
# Files
20210614_InterpoFunctions_AL.R
Main_foieGras_AL.R
# Notes
20210614_InterpoFunctions_AL.R contains the functions used in the main script Main_foieGras_AL.R
The scripts use functions of the package 'foieGras', which is now available under the name 'aniMotum': https://github.com/ianjonsen/aniMotum
Interpolated tracks were then corrected for daily surface currents (from the GLORYS12 ocean reanalysis accessed from Mercator Ocean International) and a series of oceanographic data were extracted at each location using Python code (run with Python version 3.10) from 'cooloc': https://gitlab.mercator-ocean.fr/pgiffard/coloc/-/tree/master/cooloc
2. R code (run with R version 4.2.2) used to infer behavioral states and compare turtle-habitat groups and oceanographic variables (same version provided in .Rmd and .html):
# Author
Jonathan R. Monsinjon
# Files
R-Ontogenetic shift and key foraging areas.Rmd
R-Ontogenetic shift and key foraging areas.html
# Notes
This script was used for turtle behavioral analysis, comparison of Hidden Markov Models, identification of oceanic and neritic regions, comparison of oceanographic data and time proportion allocated to each behavior, production of figures, and various exploratory tasks.
3. Data:
# File
trackingdata_movement.csv
# Notes
This file, exported via R-Ontogenetic shift and key foraging areas.Rmd, contains turtle interpolated positions centered at 12-pm with current-corrected positions, oceanic and neritic regions, estimated behavioral states, and a series of oceanographic variables GLORYS12 and LMTL-SEAPODYM.
Details on the columns are given below (label/description).
turtle/turtle's name
lon/longitude of interpolated locations (in decimal degrees; EPSG:4326)
lat/latitude of interpolated locations (in decimal degrees; EPSG:4326)
id/Argos Platform Transmitters Terminal (PTT) identification number
date/date in yyyy-mm-dd HH:MM:SS format (GMT0)
x.se/standard error of the longitude of interpolated locations (in km)
y.se/standard error of the latitude of interpolated locations (in km)
us/zonal component of estimated turtle swimming velocity (in m/s)
vs/meridional component of estimated turtle swimming velocity (in m/s)
u.se/standard error of the zonal component of turtle displacement velocity (in m/s)
v.se/standard error of the meridional component of turtle displacement velocity (in m/s)
s/stochastic volatility of interpolated locations
s.se/standard error of the stochastic volatility parameter
x/projected longitude of interpolated locations (in km; EPSG:3857)
y/projected latitude of interpolated locations (in km; EPSG:3857)
dtobs/number of hours between interpolated locations and the closest observed (Argos) location
uc/zonal component of surface current velocity (in m/s)
vc/meridional component of surface current velocity (in m/s)
thetao/sea surface temperature (in °C)
zos/sea surface height above geoid (in m)
mlotst/mixed layer thickness (in m)
ut/zonal component of turtle displacement velocity (in m/s)
vt/meridional component of turtle displacement velocity (in m/s)
lat_corr_uc/latitude of current-corrected interpolated locations (in decimal degrees; EPSG:4326)
lon_corr_uc/longitude of current-corrected interpolated locations (in decimal degrees; EPSG:4326)
mnkc/total biomass of micronekton available in the epipelagic zone accounting for the diel migration of mesopelagic micronekton (in g m-2)
mnkc_epi/biomass of epipelagic micronekton (in g m-2)
zooc/biomass of zooplankton (in g m-2)
npp/net primary production (in mg m-2 day-1)
bathy/elevation from GEBCO Gridded Bathymetry Data (in m)
speed/turtle swimming speed calculated from us and vs (in m/s)
reliable/Boolean variable: set to FALSE if x.se>8.333333, y.se>8.333333, dtobs>24, speed>0.746634
segment/segments' ID (integer) if keepsegment is TRUE
keepsegment/Boolean variable: set to TRUE if at least three consecutive daily locations available after unreliable data were filtered out
heading/turtle main direction: Unknown, South, or North
PPOW/Pelagic Province Of the World where interpolated locations were found
MEOW/Marine Ecoregion Of the World where interpolated locations were found
phase/Oceanic or Neritic if interpolated locations are within a PPOW or a MEOW respectively
segment2/level 2 segments' ID (integer) if keepsegment2 is TRUE
keepsegment2/Boolean variable: set to TRUE if keepsegment is TRUE and at least three consecutive daily locations available after locations were assigned to an Oceanic or Neritic phase
tracer/row number
step/daily step length calculated from lon_corr_uc and lat_corr_uc (in km)
angle/daily turning angle calculated from lon_corr_uc and lat_corr_uc (in radians)
state/behavioral state inferred from hidden Markov models via the Viterbi algorithm (1 is traveling, 2 is searching, 3 is foraging)
state1_probs/probability of state 1
state2_probs/probability of state 2
state3_probs/probability of state 3</p
RAPHAEL: The European Union's (Very) High Temperature Reactor Technology Project
No full textIn April 2005, as part of its 6th Framework Programme, the European Union has started a new 4-year Integrated Project on Very High Temperature Reactors (RAPHAEL: Reactor for Process Heat and Electricity). The European Commission together with the more than 30 participating companies, R&D organizations and universities from different European countries finance the project together. The project was approved because of its ambitious technical objectives and its value for education and communication. Such a reactor was found to have a large potential in terms of safety (inherent safety features), environmental impact (robust fuel with no significant radioactive release), sustainability (high efficiency, potential suitability for various fuel cycles), and economics (simplifications arising from safety features).
After the successful performance of related projects in the EU’s 5th Framework Programme which included amongst others the recovery of some of the past German experience and the re-establishment of important areas of R&D in Europe, RAPHAEL focuses now on remaining key technology needs for an industrial VHTR deployment, both specific to very high temperature and generic to all types of modular HTR with emphasis on combined process heat and electricity generation. Advanced technologies are explored in order to achieve the challenging performances required for a VHTR (900-1000°C, up to 200 GWd/tHM).
RAPHAEL is structured in a similar way as the corresponding GIF VHTR projects:
• Material selection and qualification for very high temperature components, graphite internals and vessel;
• Component development, in particular the intermediate heat exchanger;
• Fuel tests up to very high temperature and burn-up including modeling, safety tests to qualify the fuel in accidental conditions, fabrication of advanced fuel with potentially higher performance, and behavior of irradiated fuel in representative disposal conditions;
• Code qualification for reactor physics and safety analysis through comparison with experimental data;
• Adaptation of the safety approach to the VHTR specifics;
• System integration to evaluate the feasibility and performance of the entire reactor;
• Education and communication to foster understanding of the growing needs for nuclear power in general and for the technology of the VHTR in particular.
RAPHAEL together with additional national contributions to this technology relies on strong links with related EU projects which are underway or proposed, e.g. on high temperature materials, waste management (graphite and fuel), hydrogen production, GFR technology and others. The well-established European High Temperature Reactor Technology Network HTR-TN serves as the platform for the coordination of the various projects.
Significant parts of RAPHAEL may be shared with the signatories of the GIF VHTR projects.JRC.F.3 - High Flux and Future Reactor
The Legacy of Iconoclasm: religious war and the relic landscape of Tours, Blois and Vendôme, 1550-1750
No full textThis study explores the process of physically rebuilding, renewing and reinventing the relic landscape in the regions around Tours, Blois and Vendôme following the widespread iconoclastic damage of the French religious wars. The author takes a long-term perspective exploring developments over two hundred years, from the mid-sixteenth through to the mid-eighteenth centuries. The book explores what the physical renewal of the landscape can tell us about evolving beliefs and practices concerning relics during the Catholic Reformation and what reconstruction activities reveal about the meaning and experience of relic veneration. It pays particular attention to how the relic landscape evolved through relic translations and how communities that oversaw relic shrines remembered the iconoclastic acts of the religious wars through liturgical and ritual commemorations, memorials, artistic renderings, oral traditions and written accounts.Publisher PD
