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Investigation of tailored SiC/SiC composites for Sodium-cooled Fast Reactors

Abstract : Increasing the sustainability and the safety of nuclear reactors require the development of new types of reactors (GEN-IV systems) which can work as breeder (producing more fuel that it consumes) and can offer the possibility of burning minor actinides to reduce the waste, such as the Sodium- (SFR) or the Gas-cooled (GFR) Fast Reactors. Therefore, there is a need to assess materials which can withstand these very harsh core conditions. In this aim, SiC/SiC composites are promising candidates thanks to their high decomposition temperature (> 2000°C), low swelling and creep under irradiation and good neutron transparency. A recent CEA patent has highlighted that SiC/SiC-based hexagonal tubes would increase the resistance to melting and, as a consequence, the safety of the SFR core. In this way, techniques have been developed to manufacture a SiC/SiC hexagonal tube with given dimensions, which has a relatively low level of porosities and a pseudo-ductile mechanical behavior (tolerance to deformation). Besides, the chemical compatibility between SiC and SiC/SiC composites towards liquid sodium and its impurities (in particular oxygen) was investigated. For this purpose, two sets of experiments were conducted in the CORRON$^2$ facility (CEA). On the one hand, immersions up to 2000h in an oxygen-purified ([O]<10ppm) liquid sodium heated up to the nominal temperature of a SFR (550°C) were carried out. On the other hand, oxygen was inserted in the liquid sodium to reach important oxygen quantities ($[O]$ = $1000\ ppm$), well above the reference considered for incidental and transient states, to investigate the influence of this element on the SiC/SiC composites. Indeed, the SiC/SiC composites and their pyrocarbon interphase (employed to have a good linkage between the fiber and the matrix) can encounter active or passive oxidation at high temperatures. Mass assessments, SEM, XPS, X-ray tomography and tensile tests were conducted to characterize the sample properties before and after immersion. As a result, it was observed that there is no significant degradation of the material after exposure to either the oxygen–poor or –rich environments. Moreover, in some cases, an increase of the mechanical properties of SiC/SiC composites was observed.
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https://hal-cea.archives-ouvertes.fr/cea-02509774
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Submitted on : Tuesday, March 17, 2020 - 10:52:02 AM
Last modification on : Thursday, July 2, 2020 - 5:46:05 PM

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  • HAL Id : cea-02509774, version 1

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J. Braun, C. Sauder, F. Balbaud-Celerier, F. Rouillard, C. Guéneau, et al.. Investigation of tailored SiC/SiC composites for Sodium-cooled Fast Reactors. ICAPP 2016 - International Congress on Advances in Nuclear Power Plants, Apr 2016, San Francisco, United States. ⟨cea-02509774⟩

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