A previous work on open loop dynamics of nuclear rocket engines (1) is expanded to include integral temperature error feedback control of reactivity and proportional pressure error feedback control of propellant flow with first order lags placed between the desired controller positions and the actual positions. The resulting series of ordinary, nonlinear, differential equations are approximated by a linear model in order to analyze the low-frequency dynamics. It is shown that the low and high frequencies may be decoupled and that the proposed method of control is stable for small variations away from any point of steady-state operation. Algebraic equations, in terms of design parameters, are derived for control settings which yield optimum response characteristics. It is further shown that the asymptotic response is improved by reduction of the mechanical inertia of the turbopump but is independent of the thermal inertia of the core. The analysis is corroborated by analog simulation of the nonlinear model for the case of low-power-high-power transition, using only feedback control for flow and reactivity variation.