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Ryu, K.,Chae, J.-S.,Lee, E.,Parrot, M. Elsevier Science Ltd ; Pergamon 2014 Journal of Atmospheric and Solar-Terrestrial Physi Vol.121 No.1
While investigating possible precursory signatures of large earthquakes in the ionospheric data measured by the DEMETER and CHAMP satellites, we found ionospheric disturbances related to large earthquakes (M=7.2 and 7.4) that occurred on September 2004 near the south coast of Honshu, Japan. The satellite data were statistically compared with an empirical model and local averages of the large set of data in the study period. A fluctuation in the electron density above the epicenter was observed roughly 2weeks before the main earthquakes. Surveys of the space weather and geomagnetic activities suggest that these fluctuations were not caused by changes in space conditions or by a geomagnetic storm. The features were also distinct from well-known natural ionospheric anomalies. In addition, a peak-like profile in the ion temperature and lowered O<SUP>+</SUP> density around the region of the epicenter was observed a week before the main earthquakes along the satellite passes whose longitudes are close to the epicenter. The features are more apparent when they are compared with the data more distant from the epicenter, suggesting that the disturbances occur along the geomagnetic field lines. The concurrent measurements of the ion drift velocity suggest the fluctuations were triggered by the vertical plasma drift. The observed anomalies disappeared ~2 weeks after the quakes. According to the current theories on the seismo-ionospheric coupling, the horizontal electric field at the lower boundary of the ionosphere should have been strengthened by the seismic activity in order for the ionospheric plasma movements above the epicenter and its geomagnetic conjugate regions to trigger the observed ionospheric anomalies.
Isabelle Gu enot-Delahaie,Jerome Sercombe,Thomas Helfer,Patrick Goldbronn,Eric Federici,Thomas Le Jolu,Aurore Parrot,Christine Delafoy,Christian Bernaudat 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.2
The ALCYONE multidimensional fuel performance code codeveloped by the CEA, EDF, and AREVA NPwithin the PLEIADES software environment models the behavior of fuel rods during irradiation incommercial pressurized water reactors (PWRs), power ramps in experimental reactors, or accidentalconditions such as loss of coolant accidents or reactivity-initiated accidents (RIAs). As regards the lattercase of transient in particular, ALCYONE is intended to predictively simulate the response of a fuel rod bytaking account of mechanisms in a way that models the physics as closely as possible, encompassing allpossible stages of the transient as well as various fuel/cladding material types and irradiation conditionsof interest. On the way to complying with these objectives, ALCYONE development and validation shallinclude tests on PWR-UO2 fuel rods with advanced claddings such as M5® under “low pressureelowtemperature” or “high pressureehigh temperature” water coolant conditions. This article first presents ALCYONE V1.4 RIA-related features and modeling. It especially focuses onrecent developments dedicated on the one hand to nonsteady water heat and mass transport and on theother hand to the modeling of grain boundary cracking-induced fission gas release and swelling. Thisarticle then compares some simulations of RIA transients performed on UO2-M5® fuel rods in flowingsodium or stagnant water coolant conditions to the relevant experimental results gained from testsperformed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities. It showsin particular to what extent ALCYONEdstarting from base irradiation conditions it itself computesdiscurrently able to handle both the first stage of the transient, namely the pellet-cladding mechanicalinteraction phase, and the second stage of the transient, should a boiling crisis occur. Areas of improvement are finally discussed with a view to simulating and analyzing further tests to beperformed under prototypical PWR conditions within the CABRI International Program. M5® is a trademark or a registered trademark of AREVA NP in the USA or other countries.