Dynamic period equation: derivation, relation to Inhour equation, and precursor estimation [nuclear reactors]

The dynamic period equation is the basis of several successful techniques for the closed-loop digital control of nuclear reactors. These include both the reactivity constraint approach and the MIT-SNL period-generated control laws. Information on that equation is documented here including the derivation of its standard formulation, its relation to the Inhour equation, and the method used to estimate precursor concentrations so that closed-loop control can be achieved in real time. The dynamic period equation is the parent relation to the Inhour equation and as such can be used to explain the dependence of the instantaneous reactor period on both reactivity and its rate of change. It is argued that the dynamic period equation should be taught in its full form as part of nuclear engineering curricula