tPresence of U232in U233bred in thorium blanket of fast reactor is a major concern in fuel reprocessing.The former’s daughter products being hard gamma emitter and the isotope itself having substantial halflife, its presence beyond 10 ppm makes fuel recycle complicated and expensive. In this study possibilityof decreasing U232production in a typical FBR blanket by means of spectrum modification is examined.SS, depleted B4C, SiC, Mo and W regions were introduced between core and radial blanket and evolutionof isotopes were studied to arrive at an optimal configuration that satisfies requirements of breedingU233and lowering U232concentration. SS, B4C, SiC, Mo and W are known to be high temperature materialwith appropriate stability in harsh fast reactor environment. Study has shown that introducing two SSreflector rows can achieve the required low value of U232concentration without greatly compromisingthe U233production.