Title: Interaction of advanced oxide fuels with sodium in operating conditions for Sodium-cooled Fast Reactors
Citation: Proceeding Fast Reactors'13 (FR13) conference
Publisher: IAEA
Publication Year: 2013
JRC N°: JRC79777
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC79777
Type: Articles in periodicals and books
Abstract: Various types of nuclear reactors can be envisaged for the production of energy. The current worldwide fleet is mainly composed of Pressurized Water-cooled Reactors (PWR) but other options are envisaged for the next generation of reactors (i.e. liquid metal cooled reactors, molten salt reactors, gas cooled rectors, etc.). In that regard we are interested in the safety aspects of Sodium-cooled Fast Reactors (SFR) and more specifically in the potential interaction of the sodium coolant with the fuel. Though various types of fuels, e.g. nitrides, carbides, metals, are potential candidates, (U,Pu)O2 mixed oxide fuels are currently considered as reference for SFRs for which substantial experience has already been accumulated in terms of fabrication, reactor operation, reprocessing and risk assessment. However, (U,Pu)O2 mixed oxides have also various drawbacks: for instance, in case of a clad breach, though extremely rare during normal operating conditions, sodium will enter the fuel pin and react with the fuel. Studies carried out in the past in equilibrium conditions have revealed the formation of an urano-plutonate of sodium of general formula Na3MO4 with M = U1-xPux [1]. The compound thus formed is of lower density and has a lower thermal conductivity than the fuel leading to local swelling and development of hot spots that could damage further the cladding up to a pin failure. Our program of research includes the structural investigation of the following ternary systems: Na-U-O, Na-Np-O, Na-Pu-O. Our first results on the Na-Np-O system have been recently published [2]. In each ternary phase diagram investigated, numerous compounds have been identified and characterized by X-ray diffraction. In the Na-U-O system for instance, not less than ten sodium-uranate compounds are known to form (e.g. NaUO3, Na2U2O7, Na4UO5 Na3UO4, etc). At the conference we will present our most recent experimental data obtained on the above mentioned ternary systems and discussed the results. [1] M.A. Mignanelli, P. E. Potter, J. Nucl. Mat. 130 (1985) 289-297 [2] A.L. Smith, P.E. Raison, R.J.M. Konings, J. Nucl. Mat. 413 (2011) 114-12
JRC Directorate:Nuclear Safety and Security

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