Mechanisms for the Formation of Natural Temperature Dependencies in a Water-Water Reactor During Forced Circulation of the Coolant

6/30/2025 2025 - #02 Thermal physics and thermal hydraulics

Kresov D.G.

https://doi.org/10.26583/npe.2025.2.01

In PWR reactors, natural static dependencies of inlet and outlet temperatures of the reactor on the power under self-control conditions can exceed or decrease the reactor feedback gain relative to unity. The latter significantly determines the character of transient processes, manifesting itself in the amplitudes and duration of power overregulation, in pressure runouts, etc. The evolutionary development of the RP in the direction of increasing the energy reserve of the active zones led to the emergence of their new properties, including those affecting natural feedback. The work considers a number of significant factors: radial and axial unevenness of energy emission fields, as well as their influence on the T-effect depending on the type of reproduction coefficient as a function of the field. The studies are based on the known approach to the disclosure of the physical gain mechanism on the example of a special case of the representation of the zone by two channels with different heat constraints. In the work, this approach develops in a more general formulation. The limitations of the linear models used to describe the physical mechanism are discussed. On the basis of simplified models, the feedback gain factors are derived and a number of generalizations are presented for each of the factors. The difficulty of predicting their joint manifestation at the design stage was noted due to the existing design uncertainties. In this regard, it was concluded that it is advisable to use experimental data obtained at existing RP in order to clarify the initial methodological assumptions for the future.

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natural temperature dependencies feedbacks chain amplification factor unevenness of energy emission fields

Link for citing the article: Kresov D.G. Mechanisms for the Formation of Natural Temperature Dependencies in a Water-Water Reactor During Forced Circulation of the Coolant. Izvestiya vuzov. Yadernaya Energetika. 2025, no. 2, pp. 6-17; DOI: https://doi.org/10.26583/npe.2025.2.01 (in Russian).