M.S. Yurov1, V.I. Borysenko2
1 National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, 37, Beresteiskyi ave, Kyiv, 03056, Ukraine
2 Institute for Safety Problems of Nuclear Power Plants, NAS of Ukraine, 12, Lysohirska st., Kyiv, 03028, Ukraine
DOI: doi.org/10.31717/2311-8253.24.3.4
Abstract
The article presents information on the importance of determining the radiation characteristics of irradiated nuclear fuel and spent nuclear fuel at NPP power units. The radiation characteristics of nuclear fuel – activity and residual energy release – determine both the possible course of accident scenarios and the possible radiation consequences of accidents at nuclear facilities. The article presents the results of analytical modeling in the SCALE program code of changes in the activity of various isotopes of irradiated nuclear fuel of RBMK-1000 for the constant power mode and for the RBMK-1000 operation mode at actual power on the eve of the accident on April 26, 1986. The RBMK-1000 fuel assembly with an enrichment of 2.0%, which was used at RBMK-1000, was selected for modeling. The modeling results were compared with data from scientific publications on changes in the activity of RBMK-1000 nuclear fuel during its operation. The operating mode of the RBMK-1000 fuel assemblies demonstrates the significant influence on the activity of nuclear fuel. The simulation results show that the specific activity, and accordingly the total activity of nuclear fuel in the RBMK-1000 core, for the operating modes that were simulated differ significantly (namely by ~3 times) at the time of the reactor “stop”. Therefore, the actual radiation consequences in the event of nuclear fuel damage significantly depend on the operating mode, especially in the last period before the planned or unplanned shutdown of the nuclear reactor. The results of the study are important for comparing the consequences of a possible accident at a nuclear reactor with the actual and design burnup history of nuclear fuel even in the case of the same value of the achieved burnup level.
Keywords: spent nuclear fuel, specific activity of nuclear fuel, residual energy release, fuel assembly, RBMK-1000, SCALE program code.
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