Analysis of the application of natural circulation of cooling media in shipboard reactor installations

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In projects of floating facilities with a nuclear power plant, great importance is attached to the formation of a set of properties of the internal self-protection of the reactor, i. e. the development of properties that ensure its safety based on natural feedbacks, processes and characteristics. To do this, the RU project is based on physical patterns and technical solutions that prevent or minimize possible consequences from emergency situations. In particular, the natural circulation of the coolant in case of loss of power supply by the circulation pumps of the first round allows cooling the core after its transfer to a subcritical state. However, in order for a natural circulation to occur sufficient to ensure nuclear and radiation safety, certain conditions must be met in a particular case. The paper notes that the most important property of reactor installations of nuclear vessels is their ability to ensure natural circulation of the coolant in emergency situations, as well as when operating at capacity. This makes it possible to reduce the dependence of reactor plant safety on the technical condition of power supplies. Currently, natural circulation of auxiliary cooling media in passive safety systems is also widely used in reactor installations. These include emergency reactor cooling systems using an emergency cooling system, including using intermediate heat exchangers; reducing emergency pressure in the protective shell in case of an accident with a large coolant leak; cooling the reactor vessel in an out-of-design accident with the formation of corium. The paper proposes a method for preliminary analysis of the reactor plant’s ability to ensure natural circulation of the coolant, which allows us to compare various design solutions that contribute to an increase in coolant consumption during natural circulation. It is shown that for the operation of the reactor plant in stand-down mode and at energy power levels with natural circulation of the coolant, it is advisable to switch to boiling reactors. Passive safety systems using natural circulation have received special development on new nuclear vessels of projects 20870, 22220, 10510. Further development of safety systems using natural circulation to move cooling media is predicted.