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Because of their radiation resistance, ceramic materials are widely used as insulators in science and engineering and in nuclear-physical facilities.Previously, in studies of the radiation properties of SK-1 commercial steatite ceramic structural defects under highdose γ-irradiation (>10 7 Gy) were regarded as surface defects formed at the interface between a crystal (magnesium meta-silicate MgSiO 3 ) and glassy phases as a result of breaking of ≡Si-O-Mg bonds, under the polarizing action of magnesium cations, and the formation of ≡Si 3+ -O-Mg bonds [1][2][3][4].The present work studies the diffuse reflection spectra and the difference spectra (ΔR = R γ -R n-γ ) of irradiated SK-1 steatite ceramic.The conventional optical method based on studying optical absorption spectra is unsuited for most ceramic dielectrics. Even thin ceramic samples strongly absorb and scatter light. For this reason, diffuse reflection spectra, which in general are inversely proportional to the degree of absorption in the medium, can be used to evaluate the absorption. The diffuse reflection spectra of a ceramic were measured at wavelengths 200-700 nm on the apparatus whose block diagram is shown in Fig. 1.The apparatus is assembled around a SF-4A spectrophotometer and a PDO-1 diffuse reflection attachment. Depending on the wavelength range, FEU-39 and FEU-51 photomultipliers were used to detect the reflected light. The signal from the photomultiplier was fed into an M-95 microammeter. The passage scheme for the monochromatic light is as follows: the light 1 from the output slit of the monochromator strikes the PDO-1 rotary mirror 6, making a 45°angle with the optical axis of the monochromator, and then strikes at angle 90°the sample 2 or standard 3, which are placed on a PDO-1 rotary disk 4 and alternately positioned in the light beam. A PDO-1 conical mirror 5 collects the reflected light onto the photocathode of the photomultiplier. Unirradiated samples of SK-1 steatite ceramic (with the same reflection coefficient R as that of the experimental sample) were used as standards. The degree of reflection of the light was evaluated from the reflection coefficientwhere I irr and I unirr are the intensities of the light reflected from the irradiated and unirradiated samples, respectively.For measuring the diffuse reflection spectra, the wavelength resolution of the SF-4A spectrophotometer was 0.1-0.5 nm and the error in determining the diffuse reflection coefficient was 3-5%. The results were averaged over three samples. The samples were 1 mm thick, 10 × 10 mm plates as well as 15 mm in diameter and 2 mm thick disks. Their surface was ground with diamond power in order to attain the same surface diffusivity. The thickness was chosen so as to pre-

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