Power controlling apparatus for boiling water atomic reactor

Claim 1

A power control apparatus for a boiling water atomic reactor which is provided for a nuclear power plant having a boiling-water reactor with a core, a pressure vessel; an electric generator; a turbine driven by steam produced in the pressure vessel to cause the electric generator to be driven; a condenser to which the steam which has driven said turbine is conducted; a load rejection detector connected to said electric generator; and a bypass valve responsive to said load rejection detector to bypass the steam from said pressure vessel to the condenser when a load rejection occurs, in which at a time of load rejection the boiling water reactor is operated at a lower power level, said power control appartus comprising: pump means for recirculating a coolant in said pressure vessel; control rod inserting means for inserting control rods into the core; reactor status monitoring means for detecting a power output level and a coolant flow rate in the core; and control means responsive to said load rejection detector to generate a signal based on a power output level P 0 and core flow rate W 0 in the core at the time of load rejection, said signal being used for controlling whether or not the control rod should be inserted into the core, in which when said signal is greater than a predetermined value said control means permits selected control rods to be inserted into the core through said control rod inserting means and at the same time said control means permits the recirculating pump means to be operated in a minimum coolant flow rate and when said signal is less than said predetermined value said control means permits the recirculating pump means to be operated in said minimum coolant flow rate without inserting any control rods.