[en] For the case of a source disturbance in the plate type reactor there was solved the one-group diffusion equation accounting for a group of delayed neutrons and auto- and cross-power spectral densities were calculated depending on space. The present results show that for reactors of the size of BER-II (Berlin Experimental Reactor) the noise signals occurring give no useful information about the position of the source of disturbance in the frequency range relevant for disturbances generated by boiling (<40 Hz). The amplitude distribution of the noise signal is approximately identical with the steady-state flux profile. In case of very large coredimensions or also very high frequencies, however, the amplitude exponentially decreases with increasing distance from the source. (orig.)