Such flow failures also disturb the primary system and the flows in the secondary and tertiary circuits would be calculated from hydraulic balances and pump characteristics in the same way as previously discussed. How­ever, the disturbances are exhibited in the primary system as thermal changes due to a decrease in heat removal capability. Thus the core first experiences a rise in inlet temperature. As thermal disturbances, these effects will be discussed in Section 2.4.

2.2 Reactivity Perturbations

Reactivity perturbations have very much the same effect in any of the three reference systems except that the feedback coefficients may differ in value and sign. In all cases the reactivity disturbance is first noted as a rise in power and fuel temperatures and later by a rise in coolant temperatures. The Doppler coefficient is therefore most important in curtailing the transient.