Automated thermal limit monitor

This patent describes a method of blocking in real time power increases on a reactor core as a function of minimum critical power ratio having discrete monitored rod bundle groups. It includes providing initial local power range monitor readings to obtain reactor local power data in all core discrete monitored rod bundle groups via a plurality of vertical strings of local power range monitors, each string including power monitors disposed at differing elevations: providing control rod position data from a group of control rods having positions of penetration with respect to the rod bundle group for the control of nuclear reaction in the rod bundle group: providing initial flow rate through the reactor core: providing core average power data in the the reactor core: utilizing the core average power data and the initial flow rate to determine operating limit minimum critical power ratio; utilizing a reactor thermal limit output model to determine a worst initial regional minimum critical power ratio for the rod bundle group, downloading the worst initial regional critical power ratio from the computer model to memory