The article presents the results of modeling of the contamination of primary circuit of WWER-440 type reactor.The modeling has been performed using the OSCAR computer code (Nuclear research Centre in Cadarache, CEA,France), version V1.3 for decommissioning of nuclear power plants, taking into account the peculiarities of theWWER-440 reactor primary circuit, such as geometry, volumes, operational regime, materials. The results havebeen analyzed in the light of the scaling factor approach with the aim to demonstrate the modeling capabilitiesto identify the possibility of scaling factor application and to reproduce the activity correlation between difficultto measure and key nuclides. Calculated scaling factors for corrosion products are comparable with the ones ofother nuclear power plants. Calculation results of surface activity contamination confirmed the applicability of $^{60}$Co as a key radionuclide