Qualification of the Discharge Capacity of Safety Valves and Steam Dump Devices of Nuclear Power Plants

O. S. Balashevskyi

State Institution “The Institute of Environmental Geochemistry of National Academy of Sciences of Ukraine”, 34a, Academician Palladin Ave, Kyiv, 03142

https://orcid.org/0000-0003-3742-6112

Yu. S. Katsarskyi

Interagency Center for Fundamental Scientific Research in Energy and Ecology Sector of the National Academy of Sciences of Ukraine, Odesa Polytechnic and Ministry of Ecology and Natural Resources of Ukraine, 1, Shevchenko Ave, Odesa, 65044

https://orcid.org/0009-0001-9932-2880

Ye. M. Mazur

https://orcid.org/0009-0005-0936-4411

V. V. Hrybanov

https://orcid.org/0009-0005-7315-2667

H. S. Derbenov

https://orcid.org/0009-0005-1881-2853

DOI: doi.org/10.31717/2311-8253.26.2.3

Abstract

One of the relevant lessons of the Fukushima accident is that when analyzing safety and developing appropriate emergency measures, it is necessary to take into account even unlikely emergency events that can lead to negative consequences, as well as the possibility of multiple failures of emergency control systems. Safety valves of the reactor and steam generators of nuclear power plants with VVER‑1000 are designed to protect against destruction of the reactor vessels and steam generators, which undergo annual experimental reliability qualification during operational tests. However, these tests may not cover all possible emergency modes. Therefore, considering the lessons of the Fukushima accident, the development of reliability qualification methods for reactor and steam generator relief valves is of high relevance. Thus, a method for qualifying the discharge capacity of reactor and steam generator safety valves, as well as steam dump devices of safety systems under conditions of pulse thermodynamic instability has been developed. The use of this approach allowed us to establish the boundary conditions of pulse thermodynamic instability have been found with respect to the steam/steam-water flow area in the confusing section of the safety valve/ steam dump device. The discrepancy in the values of the boundary conditions of pulse thermodynamic instability for individual systems is determined by the difference in design and technical parameters and the operational test conditions. Based on the results obtained, it has been established that the prevention of pulse thermodynamic instability conditions is ensured for the considered safety valves/ steam dump devices for conditions of completely “open” flow area of the confusing section of the flow zone. The validity of extrapolation of the results of operational tests on the steam environment of the considered safety valves/steam dump devices for emergency conditions at nuclear power plants with VVER‑1000 has been found.

Keywords: qualification, safety valve, steam dump device, nuclear power facility, VVER‑1000.

References

1. Klyuchnikov A. A. (ed.) (2010). Nauchno-tehnicheskie osnovyi meropriyatiy povyisheniya bezopasnosti AES s VVER [Scientific and technical basics of measures to improve the safety of NPPs with WWER]. Chornobyl: Institute for Safety Problems of NPP of the National Academy of Sciences of Ukraine, 200 р. (in Rus.)

2. Katsarskyi I. (2024). Kvalifikatsiia vyprobuvan zapobizhnykh klapaniv reaktora [Reactor safety valve test qualification]. Lambert Academic Publishing, 145 p. (in Ukr.)

3. Mazur Y. (2024). Passive safety systems at nuclear power plants. Lambert Academic Publishing, 230 p.

Full Text (PDF)

Published

2026-06-11

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