D.Nicheva, T. Petkova (Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria) G. Avdeev (Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria) P. Petkov (University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria)

DN-6 facility (IBR-2 pulsed reactor, Dubna, Russia)