Logarithmic Power Control in KIWI-A Reactors

Power control systems for rocket propulsion reactors are unusual in that power must be increased several orders of magnitude in less than a minute. This paper describes the logarithmic power system developed at Los Alamos and used during the operation of Kiwi-A¿ and Kiwi-A3. Transfer functions are given for the system. Analog computer and experimentally measured data are presented showing the system response to step changes of logarithmic power demand, representative start-up programs, reactivity disturbances, and a rod-generated power excursion followed by a scram. The logarithmic power system had a bandwidth of one cps and a dynamic range of approximately six decades.