Validation of the KORSAR/GP Code Based on the Results of Tests of Maneuvering Conditions of a VVER Reactor with an Extended Control Range

The report presents part of large-scale work on validation of the KORSAR/GP code for the calculation of the parameters of a VVER reactor in power maneuvering regimes. The relevance of the work is due to the novel requirements for NPP power units related to maintaining a flexible schedule of electric load and the feasibility of its operational change, which is required by both Russian and foreign users of VVER technology. Over the past two years, a significant amount of experimental results obtained in testing the daily schedule of maintaining electric load by a high-power VVER reactor unit was accumulated. Ten daily cycles were tested in succession at the beginning and end of the fuel cycle. An important distinguishing feature was the application of an extended range of the secondary-circuit pressure control, which made it possible to use the coolant temperature variation as one of the main methods to affect reactivity. The first stage of the validation work, which was carried out for pretest calculations, enabled checking the qualitative coincidence of the main parameters of a reactor unit with experimental data. This study is devoted to the validation of reactor unit power and the temperature of coolant in the circulation circuits and determination of the quantitative assessment of error. Results of validation are provided for various schedules of power variation of a reactor unit and, in addition, justified conclusions are made regarding the accuracy of the computational model used in the KORSAR/GP code.