to unoccupied $4p$ states and then the $4p$ electron is recombined with the core hole with emitting x-ray in the dipole process ($E1$). It became widely known after the observation of intensities on orbital-ordering superlattice spots at Mn K-edge in LaMnO$_3$.[@Murakami98.2] At the earlier stage, the spectra were interpreted as a direct observation of orbital ordering.[@Ishihara98] However, subsequent theoretical studies based on band structure calculations revealed that the spectra are a direct reflection of lattice distortion,[@elfimov99; @Benfatto99; @Takahashi99] since the $4p$ state in the intermediate state is influenced not by the orbital ordering of $3d$ electrons but by lattice distortion through the hybridization with the $2p$ state at neighboring oxygen sites.

Different from transition-metal compounds, M$_{4,5}$ edges are available for forbidden reflection Bragg spots in actinide compounds.[@Isaacs90; @Mannix99; @Longfield02] The RXS spectra are more directly reflecting multipole orderings of $5f$ states, since the $E$1 process involves a transition from the $3d$-core to $5f$ states. Each actinide atom usually carries local multipole moments, which can order at low temperatures due to intersite interactions such as exchange interactions. For such localized electron systems, RXS amplitudes are given by summing up contributions at each site. The crystal electric field (CEF) and the intersite 