O. V. Mykhailov, A. O. Doroshenko, M. I. Pavliuchenko, S. A. Attarian
Institute for Safety Problems of Nuclear Power Plants, NAS of Ukraine, 36a, Kirova st., Chornobyl, 07270, Ukraine
DOI: doi.org/10.31717/2311-8253.23.2.3
Abstract
Data regarding the concrete temperature distribution around localization area boundaries of nuclear hazardous clusters of fuel-containing materials (NHC FCM) inside the ChNPP Shelter object (SO) were obtained during many-year scientific research. After the commissioning of a New Safe Confinement — SO complex (hereinafter NSC-SO), an expert research system (ERS) was created. ERS was put into operation instead of the information-measuring system “Finish”, which was decommissioned. A new database has been accumulated during the ERS period, but a comprehensive analysis of the measurement results was not conducted. The data obtained by ERS during 2017–2023 was investigated in detail. The general trends of temperature changes around localization area boundaries of NHC FCM are analyzed for 16 monitoring points. The results of the analysis are compared with the data obtained before the commissioning of the NSC-SO. The identified temperature trends are described using regression equations. Analysis of data measurements obtained by the ERS made it possible to determine the peculiarities of the formation of temperature dynamics in different directions of heat scattering from the localization area boundaries of NHC FCM in the conditions of the NSC-SO operation. The results of the work confirmed that the intensity of heat from NHC FCM is gradually decreasing, but in the NSC-SO, temperature gradients that provide FCM cooling with high uranium content in room 305/2 are still stored. There is reason to believe that the tendency to gradually increase the temperature of the concrete of underreactor slab around localization area boundaries of NHC FCM, which was observed during 2017–2021, has changed. There is no further increase in temperature. For almost all monitoring points, it can be expected that in 2023 the average annual temperature will return to the values set in 2021.
Keywords: Chornobyl NPP, New Safe Confinement, Shelter object, fuel-containing materials, concrete temperature, regression analysis, correlation coefficient
References
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