Development of a boron concentration prediction model using multi-cell simulation of the automatic load follow operation

Load follow operations have been performed by manually changing the boron concentration in the reactor core and moving Control Element Assemblies (CEAs) for controlling the power and the power distribution. The manual operation of load follow requires experience and predictions related to core behavior following power changes because CEA movements distort the power distribution and a boron concentration control is also inaccurate and difficult due to the long time delay in boration/dilution operations. A boron concentration prediction model, accurately predict boron concentration in the reactor coolant system, including the chemical and volume control system (CVCS) following boration or dilution, was developed in order to enhance the boron concentration control during load follow operation. The model was developed using a multi-cell concept and integrated with the KOPEC Integrated Systems Performance Analysis Code (KISPAC), which is a system code used for design purposes. Boron concentration behavior was analyzed to verify the model for both direct and indirect injection using SKN 3&4 data. The load follow operation was simulated and the results were compared with the measured data obtained during the startup period. The developed model accurately predicted boron concentration behavior for all subsystems in the reactor control system and CVCS.