Consideration is given to the use of booster rods in a D2O moderated H2O -cooled boiling water power reactor to provide reactivity control to override 135Xe buildup. A booster rod, generally containing highly 235U enriched uranium, is equivalent to a highly effluent fuel assembly. It is shown that the fuel distribution within the most effective booster rod is such that the fuel importance function is flat. Several models of booster rods are evaluated.