V. I. Skalozubov
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0000-0003-2361-223X
O. A. Dorozh
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0000-0001-8495-2911
O. S. Suhomlinov
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0009-0005-1475-7607
I. M. Verbylo
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0009-0006-3369-3896
H. S. Derbenov
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0009-0005-1881-2853
V. V. Hrybanov
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0009-0005-7315-2667
Ye. Yu. Alieksieienko
Odesa National Polytechnic University, 1, Shevchenko Ave, Odesa, 65044, Ukraine
https://orcid.org/0009-0007-0078-2646
DOI: doi.org/10.31717/2311-8253.26.2.2
Abstract
The occurrence of interchannel thermal-hydrodynamic instability in the reactor core natural circulation circuits and passive safety systems determines the potential failure to perform safety functions necessary for successful accident management for emergency core cooling and residual heat removal. A method for determining the conditions of interchannel thermal-hydrodynamic instability in the core natural circulation circuits and passive safety systems is presented, based on the analysis of stability under fluctucting deviations from the equilibrium state of pressure and flow in the natural circulation circuits. Using the NuScale modular reactor as an example, the criteria and conditions of interchannel thermal-hydrodynamic instability during accidents with significant intercircuit leaks in the steam generators (steam generator pressure exceeding 5.5 MPa) are defined. It was found that the conditions of interchannel thermal-hydrodynamic instability depend on the thermodynamic state of the coolant and coolers, structural and technical parameters, heat and mass transfer conditions in steam generators and condensers of the passive residual heat removal system, as well as the magnitude of inter-circuit leaks. The safety level of NuScale modular reactors should be reassessed, taking into account the conditions of inter-circuit thermal-hydrodynamic instability of natural circulation systems and the reliability of operational personnel management of safety-dominant accidents with significant inter-circuit leaks in steam generators.
Keywords:modular reactors, thermal-hydrodynamic instability, passive safety systems, inter-circuit leaks, coolant.
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