Interpretation of Pulsed-Source Experiments in the Peach Bottom HTGR

A general description of pulsed-source experiments is developed from the time-dependent reactor equations. The interpretation of experiments is discussed, taking into account differences in shape and spectrum between the fundamental prompt and delayed modes, and the influence of prompt and delayed harmonic modes. Pulsed-source data obtained during the zero-power commissioning program of the Peach Bottom reactor are interpreted in terms of reactivity. Using an inhour analysis, good accuracy is obtained by incorporating detailed calculations into the interpretation. It is shown that the space-dependent variation of the reactivity deduced from modified pulsed-source techniques may exceed a factor of 10 in systems like the Peach Bottom reactor.