Determination of rate change:

The determination of rate change of the logarithm of the neutron level, like in the source range, is completed through the differentiator. A differentiator measures reactor period or startup rate. Beginning rate in the intermediate range is more stable since the neutron level signal is subject to less sudden huge variations. For this purpose, intermediate-range startup rate is frequently used as an input to the reactor protection system.

The reactor protective interface gives signals for protective actions. Instances of protective actions involve control rod withdrawal interlocks and startup rate reactor trips.