Short-Interval Series Pulsing—Experimental Studies and Numerical Experiments

The technique of short-interval series pulsing a thermal reactor has been studied experimentally using the University of Illinois TRIGA Reactor. Pulse repetition rates varying from 0.5 to 3.0 pulses/min were involved. These rates represent an order of magnitude decrease in time interval between pulses compared to previous TRIGA pulsing experience. It was found that the equilibrium pulse amplitudes are strongly affected by the pulse rod reactivity, the rod drop time, and the time interval between pulses; and in the experiments, each of these parameters was maintained at a fixed value during any given series. A unique method of analysis involving the reactor kinetics equations solved in temperature has been developed to study series pulsing. This analysis shows that a further improvement by a factor of 2 to 5 for present reactor and fuel designs can be expected with certain techniques that do not require major modifications to reactor geometry or fuel. These include changing the pulse rod reactivity values between pulses, changing the time interval between pulses, increasing the rod drop reactivity, and series pulsing from elevated powers.