Local structure of molten lanthanum trichloride - alkali chloride ternary systems was analyzed in terms of Raman spectroscopy and pulsed neutron diffraction in order to accelerate the realization of pyrochemical reprocessing of nuclear spent fuels. In particular, not only vibrational modes of ionic species existing in molten LaCl3-ACl-NaCl (A = Li, K, Rb, and Cs) systems but also short. range structure in molten LaCl3-CsCl-NaCl system on behalf of the systems described before were reported in some detail, the salt combinations of which could be of prototype in the reprocessing of UO2 and/or PuO2.