The evolution of nuclear power is inseparably linked with the development of breakthrough solutions in the field of economic development of new territories. A pressing issue in this connection nowadays is generation of power for remote and hard-to-reach areas with decentralized power supply. To resolve this issue, JSC NIKIET is developing a version of the SHELF-M modular water-cooled water-moderated reactor facility as a source of power for offshore installations, including the Arctic coast areas, as well as localities with practically no power and transport infrastructure. One of the stages in justifying the safety of the reactor facility operation is to investigate the behavior of the reactor facility in dynamic transient modes at various power levels. To this end, a spatial dynamic model has been developed for the reactor facility with fuel and coolant temperature feedbacks. The dynamic model development process is a complex task that includes both preparation of constants for subsequent calculations and generation of the reactor neutronic and thermophysical models. The paper describes the development stages of the SHELF-M reactor facility spatial dynamic model and the results of coupled neutronic and thermophysical calculations for transients using the developed dynamic model of the reactor. Shim rod movement in the cold and hot states of the SHELF-M reactor facility is considered as transients.

OpenMC is a state-of-the-art Monte Carlo neutron transport simulation code that uses the Python programming language as an API. OpenMC supports eight burnout simulation algorithms. This study presents the results of choosing an integration method for modeling the burnup of fuel assemblies with burnable poisons for WWER-1000 reactors. Burnout simulation results from OpenMC were compared with those reported in the OECD benchmark. 8 different numerical integrators can be used to model burnout in OpenMC code: PI, CE/CM, LE/QI, CE/LI, CF4, EPC-RK4, SI-CE/LI, SI-LE/QI. The test results showed that the SI-CE/LI, SI-LE/QI integrators require significantly more time to calculate one burnup step than the others with the same accuracy, so they were excluded from further consideration. The PI integrator showed low integration accuracy at the same burnup steps with other integrators. However, PI has a high performance compared to other integrators, and as the integration step decreases, it converges to one solution, which can be chosen as a reference for assessing the quality of other integrators. Based on the results obtained using the fine step PI integrator, it was decided to use the CE/LI integrator for further work. The results obtained with CE/LI were compared with those obtained with the VVER-1000 LEU and MOX benchmark for codes: MCU, TVS-M, WIMS8A, HELIOS, MULTICELL and showed good agreement. Thus, we can conclude the applicability of the CE/LI integrator as part of OpenMC for modeling the burnup of fuel assemblies containing burnable poisons. During the work, the resources of the high-performance computer center of the National Research Nuclear University MEPhI were used.

The paper considers some possible input data of NPP power unit model for solving the problem of model state matching with prototype state. In the course of work on matching the state of NPP model with the prototype, a numerical experiment using full-scale modeling complex PROSTOR was conducted. Its essence was to obtain steady states of the model with capacity from 94% to 104% with a step of 0,05%. For modeling we used data of Kalinin NPP unit 3 loading 4 on 248 effective days. When analyzing the results of the numerical experiment, two effects were found. One of them, expressed in the bend of the derivative of the obtained graph, is connected with reaching the upper limit of the possibility to regulate the pressure in the main steam collector. The regulating valves on the turbine generator are the executing mechanism of pressure regulator in main steam collector. At the break of the graph they open at 100%, which causes further inability to regulate pressure. The pressure in the main steam collector starts to increase. This effect corresponds to the real processes occurring at the NPP. In this case, as one of the model tuning parameters, it is proposed to use the adaptive coefficient to the concentration of boric acid in the reactor, for the control of which, it is proposed to use a mathematical boric regulator. It was also shown that it is impossible to accurately control the pressure in the reactor due to the peculiarities of operation of the volume compensator electric heaters automatics. In this regard, it was proposed to use an additional mathematical volume compensator electric heaters regulator to match the state of the model with the prototype. These regulators have been successfully tested as part of the PROSTOR software package to match the states of the model and the prototype.