The Monte Carlo codes MCNP and MCU for RBMK criticality calculations Original Research Article

The modern Monte Carlo codes MCNP and MCU have been established as important tools to determine the neutronic behavior of reactor cores. For a comparison of their capabilities, detailed representations of seven critical experiments performed at the Russian Research Center ‘Kurchatov Institute’ were developed, identical in geometry and material composition for each code. Despite the different philosophy of code development, especially in the process of generating cross-section tables, the calculated isotopic reaction rates and the flux distributions are in excellent agreement. Effective multiplication factor and void reactivity effect agree well with experiment. Additional uniform lattice calculations confirm the equivalent potential of MCNP and MCU, but exhibit significant differences to results achieved with transport codes like WIMS-D4.