SIMULATION OF THE BOILING PROCESS OF LIQUID METALS IN MODEL ASSEMBLIES OF FAST REACTORS IN ACCIDENT REGIMES

EDN: COFZRV

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), Dolgoprudny, Russia

Sorokin A.P.1 – Chief Researcher, Nuclear Power Department, Dr. Sci. (Tech.). Contact: 1, Bondarenko sq., 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 – Leading Engineer, Nuclear Power Department.
Sorokin G.A.2 – Associate Professor, Cand. Sci. (Tech.).

Abstract

The results of the experimental studies carried out at the AR-1 stand and calculated using the modified SABENA-3D computational code for studies of the boiling of liquid metals in model fuel assemblies in the natural convection mode showed that steady bubble boiling in model fuel assemblies is observed only in a limited region of heat fluxes. Its transition to an unstable pulsed shell boiling mode is determined by various factors. The occurrence of an oscillatory process during boiling of the coolant in one of the parallel fuel assemblies leads to an out-of-phase oscillatory process in the other fuel assemblies Subsequently, oscillations in various circuits are of an antiphase nature. The hydrodynamic interaction of the circuits over time leads to a significant increase in the amplitude of fluctuations in the flow rate of the coolant in them (“resonance” of flow pulsations) and the possible “blocking” or inversion of flow rate of the coolant in the circuits, an increase in the temperature of the coolant and the shell of the fuel elements (interchannel instability effect) and, in ultimately, the occurrence of a heat transfer crisis. The cartogram of the flow regimes of a two-phase liquid metal flow differs significantly from the cartogram for water. Heat transfer during boiling of liquid alkali metals in fuel element assemblies and pipes in the range of heat flux density above 100 kW/m2 is 1.5 times higher than during boiling in a large volume. The heat transfer coefficients of fuel element simulators during boiling of liquid metal in models of fuel assemblies in single circuits and during their parallel operation are consistent with each other. The modified SABENA-3D calculation code can simulate the processes of heat transfer and hydrodynamic stability of the coolant circulation during boiling of liquid metal both in single fuel assemblies and in a parallel fuel assembly system in circuits with natural convection.

Keywords
liquid metals, fast reactors, accident situations, experiment, design codes, thermal hydraulics, boiling, core, fuel assembly, cartogram of two-phase flow modes, heat transfer, velocity, pressure, temperature

Article Text (PDF, in Russian)

References

UDC 621.039.526.034+621.039.546.8:536.2626

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2022, issue 2, 1:16