Axial power distribution monitor and display using outputs from ex-core detectors and thermocouples

This patent describes a method of monitoring the power distribution along a given axis of a core of a nuclear reactor which comprises the steps of: monitoring peripheral flux emanating from the core periphery with at least two detectors at positions exterior of the core, each detecting flux from a core quadrant and each of which detectors is located substantially along an axis substantially parallel to the given axis with the core periphery comprising no more than about two fuel assembly widths from an edge of the core; monitoring the temperature of reactor coolant flowing into the core, the temperature of the reactor coolant exiting the core in the core periphery from which a substantial portion of the detected peripheral flux emanates, and the coolant pressure of the reactor coolant system; determining the peripheral power distribution in the core periphery