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ABSTRACT

This article provides a review of the possibility of using different types of reactors to power ships. The analyses were carried out for three different large vessels: a container ship, a liquid gas carrier and a bulk carrier. A novelty of this work is the analysis of the proposal to adapt marine power plants to ecological requirements in shipping by replacing the conventional propulsion system based on internal combustion engines with nuclear propulsion. The subjects of comparison are primarily the dimensions of the most important devices of the nuclear power plant and the preliminary fitness analysis. It was assumed for this purpose that the nuclear power plant fits in the engine room compartment and uses the space left after the removal of the combustion engines. At the same time, this propulsion provides at all times sufficient energy for port, technological and shipping operations at an economically justifiable speed. For deep-sea vessels, which are supposed to reach null emissions of CO, CO2, NOx, SOx and H2O, this is one of the most reasonable solutions. Finally the paper proves that all the above-mentioned marine functions could be effectively applied in power plants equipped with 4th generation nuclear reactors.

Due to the current trends aiming to reduce carbon dioxide emissions by increasing the use of renewable energy sources, changes are required in the operation of coal-fired steam units. The unstable nature of renewable energy sources, depending on weather conditions, means that the amount of energy produced varies and is not always in line with peak demand. To ensure the security and stability of energy supplies in the energy system, renewable sources should cooperate with units independent of environmental conditions. With conventional steam systems, the main issue of such energy storage applied to steam turbine units presented in the paper, which, in the event of a need for a sudden reduction of the system load, prevents overloading of the boiler and turbines, improving the safety of the system. This article presents a thermodynamic model of this energy storage. A zero-dimensional (0D) model was implemented, including the operating parameters of the unit. This model directly relates to the thermodynamic parameters defined at specific points of the thermodynamic cycle. Based on the 0D model, it was shown that the process of loading the energy storage with steam leads to a load reduction of up to 4%. On the other hand, when discharging the stored energy, the net power of the steam block may increase by 0.4%. For more detailed analysis, a three-dimensional (3D) non-equilibrium with including cross effects approach was applied. This approach is based on flow models, with phase transitions that determine temperature fields, densities, phase transition in relevant space, and is used for more accurate analysis. Here we investigate the relationship between the 0D and 3D approaches in the context of steam storage. The combination of these two approaches is the fundamental novelty of the article.

The article presents results of efficiency calculations for two 560 MW nuclear cycles with high-temperature gas-cooled reactor (HTGR). An assumption was made that systems of this type can be used in so-called marine nuclear power plants. The first analysed system is the nuclear steam power plant. For the steam cycle, the efficiency calculations were performed with the code DIAGAR, which is dedicated for analysing this type of systems. The other system is the power plant with gas turbine, in which the combustion chamber has been replaced with the HTGR. For this system, a number of calculations were also performed to assess its efficiency. Moreover, the article names factors in favour of floating nuclear power plants with HTGRs, which, due to passive safety systems, are exposed to much smaller risk of breakdown than other types of reactors which were in common use in the past. Along with safety aspects, it is also economic and social aspect which make the use of this type of systems advisable.