Epitaxial 4H-SiC 1.2 kV PiN diodes have been evaluated using IN measurement techniques after exposure to 1, 2, 3.8 and 10 Mrad irradiation from the Co-60 gamma source. After accumulated gamma dose of 10 Mrad the diodes were exposed to UV irradiation. The forward and reverse diode characteristics were measured successively in the temperature range from RT to 350degreesC. The leakage current increases with gamma irradiation dose up to about 4 Mrads by a factor of 20 compared to the pre-irradiation values. After an accumulated dose of 10 Mrads the leakage current decreases by about one order of magnitude but is still about 2-3 times larger than before irradiation. The decrease in reverse current is accompanied by the appearance of the high noise. The apparent thermal activation energies increase with the gamma irradiation dose and show a relatively large spread in values especially at lower temperatures (150degreesC to 250degreesC). The UV irradiation has a positive effect on the IN characteristics. The reverse current is lowered by one order of magnitude compared to the pre-irradiation level. The large noise in the leakage current is absent after UV exposure. The low energy level of 0.2 eV appears clearly in the temperature range between 150degreesC and 250degreesC after the UV irradiation. The thermal activation energy of 0.91 eV has been determined for the deep energy level in the temperature range from 250degreesC to 350degreesC. The values of the thermal activation energies are very consistent between diodes and show less spread as a function of the applied voltage. The Poole-Frenkel dependence with local field enhancement can be fitted to the 0.91 eV level.