We analyzed the energy transfer efficiency from the polystyrene (PS) host to a fluorescentmolecule, 2-(4-tert butylphenyl)-5-(4-phenylphenyl)-1,3,4-oxadiazole (b-PBD), in PS-b-PBDbinary and PS-borosilicate–b-PBD ternary scintillation materials. The Förster radius was estimatedon the basis of the absorption and emission spectra of b-PBD and PS, respectively. In addition,the energy transfer efficiency was analyzed using a phenomenological model and the emissionintensity from the PS host. Consistent results were obtained by these two approaches. The analysisof the energy transfer process, in combination with the analysis of concentration quenching, leadsto an estimation of the optimum b-PBD concentration. The estimated concentration was in goodagreement with the actual optimum concentration confirmed by measuring radioluminescencespectra. These results indicate that the analysis of the energy transfer process described in thispaper is an effective way to estimate the optimum fluor concentration even for ternary scintillationmaterials with nanoscale structures.