Methodology for determining the conditions for the occurrence of steam explosions during accidents with complete power outages and inter-circuit leaks at nuclear power plants with VVER
DOI:
https://doi.org/10.15276/opu.2.72.2025.07Keywords:
accident, compete power outages, intercircuit leak, steam explosion, nuclear power plantAbstract
A deterministic method has been developed to determine the conditions and consequences of steam explosions during complete power outages accidents with inter circuit leaks at nuclear power plants with WWER/PWR reactors. The required conditions for steam explosions are determined based on the principle of thermodynamic instability of systems – a simultaneous increase in pressure and mass in the steam volumes of the reactor and/or steam generator corresponds to the conditions for steam explosions. The determining parameters of the conditions for steam explosions are the rates of increase in pressure and steam volume. The consequences of steam explosions are determined by the energy capacity of steam explosions, which depends on the rate of increase in pressure and steam volume. Based on the developed method, the most critical situations regarding the conditions and consequences of steam explosions of complete power outages accidents with intercircuit leaks have been found for nuclear power plants with WWER/PWR reactors. The required conditions for successful qualification for opening the safety valves of the reactor and steam generator, as well as the steam dump devices of the steam generator under steam explosion conditions, have been found. The need to modernize the emergency feed system of the steam generator volumes has been recognized for the effective management of out with intercircuit leaks of nuclear power plants with WWER/PWR reactors and the prevention of the conditions and consequences of steam explosions. The developed methods to determine the conditions for steam explosions at nuclear power plants can be included in the deterministic codes for modelling accidents with a “tight” reactor circuit/intercircuit leaks in the volume of steam generators, as well as in the operational documentation (manuals/instructions for accident management) for the improvement/ modernization of accident management strategies at nuclear power plants with WWER/PWR reactors.
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