Análise termo-hidráulica do elemento combustível de maior potência do reator SMART usando os códigos STHIRP e OpenFOAM

Abstract

Projections for global electricity demand in the medium and long term show a sharp incre- ase in Brazil. There are several regions in the country that are disconnected from the National Interconnected System (SIN), which require their own electricity generation systems to meet local demand. In this sense, Small Modular Reactors (SMRs) are an attractive option for meeting the demand in these regions. These reactors can be fabricated and subsequently transported to regions of interest in order to supply isolated regions. Among the modular reactors, the SMART modular reactor has a design based on the PWR, the most widely used reactor in the world today. This fact makes it an attractive solution for Brazil, since the country already has industrial experience in the production of fuel elements and in the operation of this type of reactor. The SMART has a nominal power of 330 M WT h, being capable of meeting the electricity demand of a city with approximately 100,000 inhabitants. This work performs a thermal-hydraulic analysis of the highest power element of the SMART reactor in steady state at the beginning of the burning cycle. For this purpose, two programs were used: STHIRP and OpenFOAM, in order to obtain the main thermal parameters in the hottest region of the reactor. The results for the element were obtained through the construction of two independent thermal models, one for each program. During the present work, the two programs were used in a complementary manner, so that the results in common between the two programs were compared and the particular results of both presented in a complementary manner. The main results obtained by the programs include the distributions of temperature, pressure and coolant flow velocity, as well as the temperature profile in the rods. In the present work, the total variations of pressure and temperature of the hottest element calculated by the two programs are compared with each other and, particularly in the case of temperature, are compared with the result predicted by theory. The overall results obtained by the two programs showed good agreement with each other and with the values predicted theoretically, when an energy balance was applied to the simulated system. To demonstrate the capability of the thermal models developed in the present work for predictions, particularly using the STHIRP program, the DNBR profile of the reactor was calculated for 100% and 115% of the nominal reactor power.