Results of precision calculations of three-dimensional power density in VVER-1000 core with feedbacks using MCU code

Accounting of feedbacks on the density and temperature of the coolant, the fuel temperature, as well as on the equilibrium concentration of xenon is important for VVER reactors, since it has a significant influence on the neutron-physical characteristics of such systems. Therefore, there is a need to incorporate feedbacks into precision calculations of the power density of the VVER-1000 core. In the present work, we used a model of the core, divided into 30 layers by height. The calculations were carried out by means of Russian Monte Carlo code MCU (Monte-Carlo Universal). Individual values of densities and temperatures of the coolant, the fuel temperatures, as well as the equilibrium concentration of xenon were calculated in each layer of every fuel assembly. In addition, power density was calculated pin-by-pin in each layer. The obtained results were compared to the results obtained by means of the certified BIPR-7A code. It is shown that within a reasonable computational time using currently available hardware resources one can obtain the three-dimensional power density with an acceptable accuracy and taking into account the feedbacks on the density and temperature of the coolant, the fuel temperature, as well as the equilibrium concentration of xenon.