PURPOSE: A power control method of a nuclear power plant is provided to prevent a trip by reducing the power of the nuclear power plant when a fuel tube is replaced. CONSTITUTION: A trip set value is controlled by reducing the power of a nuclear power plant when a fuel tube is replaced. The power of a neutron high power system detector is maintained below the trip set value. A rise history of the neutron high power system detector is analyzed according to a discharge burn-up of the fuel tube.
