The present invention belongs to the technical field of
nuclear reactor design, and particularly relates to an in-core detection-based passive start-up method. A
neutron detector is provided inside a reactor core fuel
assembly. In an initial state of reactor start-up, a
coolant is at
room temperature, all control rods are inserted into a reactor core and a
boron concentration is a shutdown
boron concentration, the
neutron detector obtains an effective count rate
signal of not less than 0.5cps. During subsequent start-up, as the temperature of the
coolant increases, the control rods are withdrawn from the reactor core or the
boron concentration decreases, the
neutron detector count rate exhibits a continuous increase,
no detection blind zone is present, and real-time monitoring of inadvertent reactivity
insertion is achieved, thereby enabling a reactor to reach a critical state safely and effectively. Additionally, by taking into account variations of the neutron detector count rate during the start-up, reactivity
insertion processes of rod withdrawal and boron
dilution are guided. The present invention uses the neutron detector arranged in the reactor core fuel
assembly to realize blind-zone-free monitoring during the entire start-up process, thereby ensuring safe and efficient passive stat-up of the reactor.