Experimental demonstration of automated reactor startup with on‐line reactivity estimation

A generic method for performing automated startups of nuclear reactors described by space‐independent kinetics under conditions of closed‐loop digital control was developed, implemented, and tested on the 5‐MWt MIT Research Reactor. The technique entails first obtaining a reliable estimate of the reactor’s initial degree of subcriticality and then substituting that estimate into a model‐based control law so as to permit a power increase from subcritical on a demanded trajectory. The estimation of subcriticality is accomplished by application of the ‘Perturbed Reactivity Method’ which was developed in the course of this research. The shutdown reactor is perturbed by the insertion of reactivity at a known rate. Observation of the resulting period permits determination of the initial degree of subcriticality. A major advantage to this method is that repeated estimates are obtained of the same quantity. Hence, statistical methods can be applied to improve the quality of the calculation. In addition to describ...