  Amorphous, glass, and glass-ceramic materials practically always include a
significant number (more than eight) of crystalline phases, with the contents
of the latter ranging from a few wt.% to several hundredths or tenths of wt.%.
The study of such materials using the method of X-ray phase analysis faces
difficulties, when determining the phase structure. In this work, we will
develop a method for the analysis of the diffraction patterns of such
materials, when diffraction patterns include X-ray lines, whose intensities are
at the noise level. The identification of lines is based on the search for
correlations between the experimental and test lines and the verification of
the coincidence making use of statistical methods (computer statistics). The
method is tested on the specimens of a-quartz, which are often used as standard
ones, and applied to analyze lava-like fuel-containing materials from the
destroyed Chornobyl NPP Unit 4. It is shown that the developed technique allows
X-ray lines to be identified, if the contents of separate phases is not less
than 0.1 wt.%. The method also significantly enhances a capability to determine
the phase contents quantitatively on the basis of lines with low intensities.
