A functional optimization technique based on the abstract minimum norm problem in Hilbert spaces is applied to obtain a suboptimal control policy for the problem of adjusting the flux distribution, in finite time.Restricting the control action to be expanded in terms of a finite set of arbitrary known functions of time, the infinite dimensional control problem is reduced to a finite dimensional one. The control action is subject to linear constraints. The method is described for a general, linearized, distributed reactor model. An example is presented.