This concluding chapter gives a brief summary of significant experiences with dynamics tests in nuclear reactors. An extensive bibliography is included so that the reader can find further information easily.

8.1. Pressurized Water Reactorsf

Several tests on pressurized-light-water reactors have been performed. Oscillator and PRBS tests were used at Saxton (20 MW) and PRBS tests were used at Yankee (600 MW) and Trino (825 MW). The experiences at Yankee and Trino are particularly significant because these tests were performed under conditions that are similar to conditions in new, larger PWRs. Rajagopal and Gallagher (5, 6) used normal system hardware to introduce 127-bit PRBS signals with bit durations of 0.5 and 6 sec. This work shows that the magnetic jack control rod drive mechanism (see Section 7.3) is capable of introducing large enough reactivity perturbations at a high enough rate to give frequency response results over the range of important frequencies for a PWR.

Rajagopal and Gallagher (5) also used their test results for system identifica­tion purposes. They approximated the feedback effects by two first-order lags. One was for the Doppler effect in the fuel and the other was for delayed

effects associated with the coolant and structure. They were able to evaluate the two gains and the two time constants in this simple model.