%0 Conference Paper %F Oral %T Nuclear fuel behaviour at high temperature new insights from post-test examinations on the VERDON-1 sample %+ CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)) %A Gallais-During, A. %A Geiger, E. %A Le Gall, C. %A Lamontagne, J. %A Bernard, S. %A Gleizes, B. %A Pontillon, Yves %A Hanus, E. %A Ducros, G. %< avec comité de lecture %B Top Fuel %C Boise, United States %I Top Fuel 2016 - Light Water Reactor (LWR) Fuel Performance Meeting 2016 %8 2016-09-11 %D 2016 %K oxidizing %K reducing atmosphere. %K Severe accident %K fission products release %Z Physics [physics]/Nuclear Experiment [nucl-ex] %Z Physics [physics]/Nuclear Theory [nucl-th]Conference papers %X In order to reduce the uncertainties concerning Source Term assessment under Light Water Reactor(LWR) severe accident conditions, 4 VERDON tests were recently performed. They have been defined in theframework of the International Source Term Program and carried out at CEA Cadarache, in the LECA-STARfacility. Among these 4 VERDON tests, VERDON-1 test was devoted to high burn-up UO$_2$ fuel behavior and FPrelease under H$_2$ reducing conditions at very high temperature.This test was performed with the Release Circuit, which is devoted to the precise characterization of the FP release,in terms of FP release kinetics and fission products (FPs) released fraction. The main components of the circuits area furnace heating the fuel sample, a filter trapping the emitted aerosols and gamma spectrometry detectors for online and post-test measurements. VERDON-1 test was conducted up to about 2600°C without reaching global fuelrelocation, allowing thereby post-test micro-analyses.After a brief description of the fuel sample nature and the experimental set-up, we present the progress of theexperimental sequence and the associated gamma spectrometry measurements. We then focus on the major resultsof the VERDON-1 tests regarding the fuel global behavior. These results are obtained by two complementarytechniques. First, the fuel sight gamma station can be used either on-line to detect fuel relocation or just after thetest, as a longitudinal bench, to get preliminary information on the global shape of the fuel sample inside thefurnace. Secondly, these information are completed by post-test examinations performed on the fuel sample afterextraction from the furnace. Complete qualitative and quantitative characterizations, including EPMA and SEManalysis, were performed for the first time at the CEA Cadarache on a sample that has been submitted to such severeaccident conditions. These results show an advanced state of sample degradation, with locally previously moltenareas, meaning that fuel global relocation was imminent by the end of thermal-hydraulic sequence. The relocationtemperature is compared to that of previous VERCORS tests and discussed regarding the atmosphere of the test andpossible UO$_2$-ZrO$_2$ interaction. %G English %2 https://cea.hal.science/cea-02438702/document %2 https://cea.hal.science/cea-02438702/file/201600002513.pdf %L cea-02438702 %U https://cea.hal.science/cea-02438702 %~ CEA %~ DEN