Abstract: A control strategy for a pressurized water nuclear reactor that employs separate, independent control rod banks for respectively controlling Tavg and axial offset within corresponding deadbands. The strategy does not permit the control banks controlling reactor core power and the control banks controlling axial offset to move together, but normally gives preference to the control banks controlling the Tavg except when a demand signal is received simultaneously by both independent control rod banks to move in a same direction, in which case, the control bank compensating for the axial offset is given preference.

Abstract: A control strategy for a pressurized water nuclear reactor that employs separate, independent control rod banks for respectively controlling Tavg and axial offset within corresponding deadbands. The strategy does not permit the control banks controlling reactor core power and the control banks controlling axial offset to move together, but normally gives preference to the control banks controlling the Tavg except when a demand signal is received simultaneously by both independent control rod banks to move in a same direction, in which case, the control bank compensating for the axial offset is given preference.

Abstract: This invention provides a method of operating a nuclear reactor having a negative reactivity moderator temperature coefficient with the object of maintaining a uniform and symmetric Xenon distribution above and below substantially the center of the core over a substantial axial length of the core during normal reactor operation including load follow. In one embodiment variations in the Xenon distribution are controlled by maintaining a substantially symmetric axial power distribution. The axial offset, which is employed as an indication of the axial power distribution, is maintained substantially equal to a target value, which is modified periodically to account for core burnup.

Abstract: The neutron absorbing medium in a reactor is changed in dependence upon the loading of the reactor, or any other operating mode where the power distribution axially is to be maintained within acceptable limits, by varying the chemical shim in the coolant of the reactor. The error for effecting the change is derived by comparing the average temperature of the coolant and a reference temperature which is a programmed function of the power delivered by the turbine energized by the reactor. The reference temperature is derived by converting the turbine impulse chamber pressure into a temperature parameter. A compensated temperature error is derived from an electrical compensating network typically a PID controller. At the input of this network an electrical analog of the temperature error is impressed and its output, a compensated temperature error, is derived. The correcting command is derived from the output of a non-linear gain network.