A novel concept of immobilization of light water nuclear reactor fuel reprocessing waste effluent through interaction with sodium zirconium phosphate (NZP) has been established. It was found that a large number of hazardous cations could be loaded in the NZP-based matrix without significant change of three-dimensional framework structure. Starting from the raw powder diffraction data of polycrystalline solid phases, crystal structure of substituted NZP phases has been investigated using the General Structure Analysis System (GSAS) package. Cation(s) substituted NZP phases crystallize in rhombohedral symmetry (space group R-3c and Z = 6). Powder diffraction data have been subjected to Rietveld refinement to reach satisfactory structural convergence of R-factors. Unit cell parameters, inter atomic distances, bond angles, reflecting planes (h, k, l), structure factors, polyhedral (ZrO6 and PO4) distortion, and particle size have been reported. PO4 stretching and bending vibrations in the Infra red (IR) region have been assigned. SEM and EDAX analysis provide analytical evidence of fixation of cations in the matrix.