Enrichment Zoning and Control Rod Programming for Reactivity and Power Shape Control

An efficient optimization method has been developed that determines simultaneously beginning-of-cycle (BOC) enrichment distribution and the control rod programming in reactors that lose reactivity during burnup such that (a) reactor criticality and a desired power distribution are satisfied throughout the cycle and (b) all the control rods are withdrawn at end-of-cycle (EOC). The method uses (a) an iterative scheme of uncontrolled burnup calculations [and linear programming (LP) for more than two enrichment zones] to determine a good approximation of the EOC reactor composition that satisfies reactor criticality and the desired power distribution and (b) LP in a reversed burnup process starting from the EOC conditions to determine the control rod programming and the BOC enrichment distribution.