ADAPTATIONS OF RESULTS OF EXPERIMENTAL QUALIFICATION OF PASSIVE SAFETY SYSTEMS OF NUCLEAR POWER PLANTS

Abstract

Problems. An urgent issue of ensuring the safety of nuclear power plants is the adaptation of the results of experimental qualification of the fittings of passive safety systems in a single-phase environment to emergency conditions of two-phase flows. For most of the equipment of systems important for the safety of nuclear power plants, there is no principled possibility of qualification through direct tests in emergency conditions. The experience of operating nuclear power plants, as well as the results of simulations after design accidents, determined the possible inconsistency of the operating conditions of the fittings in emergency situations and in the modes of operational tests with a single-phase steam-gas environment.Thus, it is necessary to adapt the results of the experimental qualification of the fittings of the emergency steam and gas removal systems in a single-phase environment to the emergency conditions of two-phase flows. The aim of the study. The purpose of this article is sufficient justification of the adaptation of test results on a single-phase environment to the conditions of emergency processes with a two-phase environment. Methodology of implementation. To achieve the goals of the study, deterministic modeling of the conditions and criteria of operation/testing of valves of emergency steam and gas removal systems was used. Research results. T An analysis of the validity of the results of the experimental qualification was performed for the dynamic pressure pressure on the closing device in the test mode (single-phase flow mode) and the dynamic pressure pressure on the closing device in the emergency mode (two-phase flow mode). The adaptation of the results of the experimental qualification for closing the valves of the emergency steam and gas removal systems in a single-phase environment to the emergency conditions of two-phase flows was carried out under the conditions of subsonic and supersonic flow regimes. Conclusions. The conditions for adapting the results of the experimental qualification for closing the valves of the emergency vapor gas removal systems to the emergency conditions of subsonic and transonic flows of two-phase flow in the flow part of the valves have been determined. The dynamic pressure on the closing device of the valve in single-phase flows of operational tests and the dynamic pressure in two-phase flows of emergency modes are considered qualification criteria.