[en] (Th,Pu)O_2 mixed oxide (MOX) fuel was fabricated with 1% PuO_2 for experimental irradiation in Advanced Heavy Water Reactor (AHWR) of India. A new analytical technique was explored for characterising MOX fuel for homogeneity using optical property evaluation of Polyallyl Diglycol Carbonate (PADC) which is commercially known as CR39, irradiated with alpha particles from the fuel samples. The fabrication of the fuel was carried out using two different routes viz; conventional powder metallurgical route (POP) and the coated agglomerate particle (CAP) based route. These pellets were earlier analysed for homogeneity using X-ray diffraction technique and found that CAP sample had lower level of Pu homogeneity as compared to POP sample. The pellets were prepared similar to ceramography samples and placed on CR39 film with aluminium mylar of thickness 11μm for a pre decided time period (30s in this case) for exposure. Since the specific activity of plutonium (0.06 Ci/g) is significantly higher than that of thorium (1.1 X 10"-"7 Ci/g), the effect on the film could be attributed to presence of plutonium. The film was decontaminated and chemically etched to enhance the radiation effect caused on it using 6N KOH at 72°C for 90 minutes. The etched and dried CR39 film was analysed for UV-Vis absorption properties using JASCO V 650 spectrophotometer. The samples (portions of the film) bombarded with alpha particles showed a decrease in the peak intensity and a shift of the peak maxima in the absorption spectra as compared to pristine CR 39 sample. There was a decrease in the band gap energy observed between samples irradiated with CAP and POP pellets which could be attributed to the different levels of Pu heterogeneity in the pellets. All the results could be attributed to irradiation induced changes in the bond structure within the polymer CR39. (author)