PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY
Series: Nuclear and Reactor Constants

since 1971

Русский (РФ)

ISSN 2414-1038 (online)

GENERALIZATION OF THE RESULTS OF EXPERIMENTAL AND NUMERICAL SIMULATION OF BOILING OF ALKALINE LIQUID METALS IN THE CORE OF FAST REACTORS (CARTOGRAM OF TWO-PHASE FLOW REGIMES, HEAT TRANSFER)

EDN: YHJJPS

Authors & Affiliations

Sorokin A.P.1, Kuzina Yu.A.1, Denisova N.A.1, Sorokin G.A.2
1 A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
2 Moscow Institute of Physics and Technology (National Research University), Moscow, Russia

Sorokin A.P.1 – Chief Researcher, Dr. Sci. (Tech.). Contacts: 1, pl. Bondarenko, Obninsk, Kaluga region, 249033. Tel.: +7 (905) 641-20-99; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..
Kuzina Yu.A.1 – Head of the Nuclear Power Department, Cand. Sci. (Tech.).
Denisova N.A.1 – Lead Engineer.
Sorokin G.A.2 – Associate Professor, Cand. Sci. (Tech.).

Abstract

The results of a series of experiments carried out at JSC “SSC RF – IPPE” on heat exchange and circulation stability during boiling of a sodium-potassium alloy on models of single fuel assemblies and in a system of parallel fuel assemblies are presented, taking into account the influence of various factors on the boiling process in the natural convection mode. The data obtained showed that the regime of stable nucleate boiling is observed only in a limited region of heat flows; its transition to the regime of unstable pulsating slug boiling is determined by various factors. The boundaries of the transition from bubble to slug, dispersed-ring and dispersed flow regiones of a two-phase flow of liquid metal in a fuel assembly are approximated by simple dependencies. The occurrence of an oscillatory process during boiling of the coolant in one of the parallel fuel assemblies leads to an antiphase oscillatory process in the other fuel assembly; subsequently, oscillations in different circuits are of an antiphase nature. Hydrodynamic interaction of circuits can lead to a significant increase in the amplitude of fluctuations in coolant flow in them, “resonance” of flow pulsations, possible “locking” or inversion of coolant flow in the circuits, an increase in the temperature of the coolant and fuel rod cladding (the effect of interchannel instability) and a heat transfer crisis. The experimentally discovered effect of the influence of fuel rod surface roughness on heat transfer and flow regimes during boiling of liquid metal in fuel rod assemblies is demonstrated. The results of experiments on heat transfer during sodium boiling in natural and forced convection regimes in a fuel assembly model with a “sodium cavity” located above the reactor core show that it is possible for long-term cooling of fuel elements in a fuel assembly with sodium for these conditions. The results of analysis and generalization of data on and cartogram of two-phase flow regimes and heat transfer during boiling of alkali liquid metals in fuel rod assemblies of fast reactors are presented. The possibility of modeling heat transfer and circulation stability during boiling of alkali liquid metals both in single fuel assemblies and in a system of parallel fuel assemblies in circuits with natural coolant circulation using a channel-by-channel model of thermo-hydraulic calculation of two-phase flows with phase separation is demonstrated. The results of comparison of data from computational and experimental studies are presented.

Keywords
fast neutron reactor, fuel assembly, experiment, numerical modeling, alkali liquid metals, hydrodynamics, heat transfer, boiling, circulation stability, interchannel instability, heat transfer, heat transfer crisis, regime map, two-phase flow regimes

Article Text (PDF, in Russian)

References

UDC 621.039.526.034+621.039.546.8:536.26

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2024, no. 1, 1:11