Identities, quantities, and costs associated with producing a set of selected enrichments and blending them to provide fuel for existing reactors are investicated using on optimization model constructed with appropriate constraints. Selected enrichments are required for either nuclear reactor fuel standardization of potintial uranium enrichment alternatives such as the gas centrifuge. Using a mixed-integer linear program, the model minimizes present worth costs for a 39-product-enrichment reference case. For four ingredients, the marginal blending cost is only 0.18 percent of the total direct production cost. Natural uranium is not an optimal blending ingredient. Optimal values reappear in most sets of ingredient enrichments. / Master of Science