Excess currents of the different nature in 6H-SiC pn structures of the different origin and parameters were investigated. The effect of the suppression of the forward and reverse excess currents were observed after 0.9 MeV electron (dose 5x10(16) ÷ 1.6x10(17)) and 8 MeV proton (dose 5x 10(15) cm(-2)) irradiation for structures with shunts which is probably due to the presence of relatively small inhomogeneities. The shunts in another group of pn structures probably are more high capability and they are more stable against degradation during irradiation.