Method of monitoring axial power distribution using axial offset signals

Purpose: To always enable exact and rapid monitoring for the axial power distribution in a method of monitoring the axial power for the core of PWR type reactor from outside of the core. Constitution: Power range neutron detectors for detecting the power in the axial upper half and power range neutron detectors for detecting the power in the lower axial half of the reactor core are disposed to the outside of the core and axial offset signals are taken out from each of the detectors. The reactor core is divided axially into three portions of: Zb < Z < Z1, Z1 < Z < Z2 and Z2 < Z < Zt, where Zb represents the axial position of the reactor core bottom, Z1 represents the axial position of the power peak in the lower half of the reactor core, Z2 represents the axial position of the power peak in the upper half of the reactor core and Zt represents the axial position of the reactor core top. Then, the axial power is monitored for each of the three portions by introducing the axial direction power distribution by using the axial offset signals. (Horiuchi, T.)