Method of reactor control

Purpose: To maintain reactor stability rapidly and surely in BWR type reactors. Method: By utilizing the fact that the reactor power is most unstable where the coolants are recycled spontaneously in BWR type reactors, it is judged if the power is stable or not by the reactor core flow rate and the power level of the neutron detectors. Control rods are inserted only in the unstable regions depending on the above judgement and the power in the unstable regions is decreased and stabilized. That is to say, the reactor core flow rate (W), local power (P1) and the average reactor core power (P2) are detected and the control rods are inserted to the reactor core in the regions satisfying the following conditions; W <= a(P2)2 + b(P2) + c; (P1)/(P2) > d; and (P1) > e; where a,b,c,d,e represent previously determined constants. (Ikeda, J.)