Assessment of radioactive contamination in primary circuit of WWER-440 type reactors by computer code OSCAR for the decommissioning case

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 the WWER-440 reactor primary circuit, such as geometry, volumes, operational regime, materials. The results have been analyzed in the light of the scaling factor approach with the aim to demonstrate the modeling capabilities to identify the possibility of scaling factor application and to reproduce the activity correlation between difficult to measure and key nuclides. Calculated scaling factors for corrosion products are comparable with the ones of other nuclear power plants. Calculation results of surface activity contamination confirmed the applicability of 60Co as a key radionuclide. •Contamination modeling by OSCAR code (CEA France) of reactor primary circuit.•Nuclide surface activities analyzed by scaling factor approach for decommissioning.•The good correlation of key and difficult to measure nuclides predicted and analyzed.•The modeling can be used for identification of places for surface activity sampling.