Abstract This paper presents the results from molten core–concrete interaction (MCCI) reactor benchmark test cases, performed in the frame of European Severe Accident Research Network of Excellence (SARNET2). VVER-1000 nuclear power plant at Kozloduy site was chosen as a reference for the benchmark test-cases. The initial conditions for MCCI calculations were taken from a Station Blackout (SBO) scenario calculated with severe accident computer code ASTEC version 1.3R2 by INRNE. Six participants from different countries (INRNE, Bulgaria; TUS, Bulgaria; GRS, Germany; KIT, Germany; IRSN, France; NUBIKI, Hungary) were involved in this project. Two different computer codes were used to perform two independent calculations: ASTEC and WECHSL, each one representing the main phenomena arising during the interaction between the corium and the reactor pit concrete in dry conditions and in case of corium reflooding. The purpose of the analysis is to compare results obtained by the different computer codes in the reactor test cases as well as to compare modeling and the best-estimate assumptions in the models used in the available MCCI codes. The other purpose is to synthesize conclusions on the major uncertainties in the models used in these codes.