Interaction between nuclear graphite and molten fluoride salts: a synchrotron radiation study of the substitution of graphitic hydrogen by fluoride ion.

Xinmei Yang, Shanglei Feng, Xingtai Zhou, Hongjie Xu, T K Sham

Index: J. Phys. Chem. A 116(3) , 985-9, (2012)

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Abstract

The interaction between nuclear graphite and molten fluoride salts (46.5 mol % LiF/11.5 mol % NaF/42 mol % KF) is investigated by synchrotron X-ray diffraction and C K-edge X-ray absorption near-edge structure (XANES). It is found that there are a large number of H atoms in IG-110 nuclear graphite, which is attributed to the residual C-H bond after the graphitization process of petroleum coke and pitch binder. The elastic recoil detection analysis indicates that H atoms are uniformly distributed in IG-110 nuclear graphite, in excellent agreement with the XANES results. The XANES results indicate that the immersion in molten fluoride salts at 500 °C led to H atoms in nuclear graphite partly substituted by the fluorine from fluoride salts to form C-F bond. The implications of these findings are discussed.