[en] This analysis discusses the historical experience of operating Light Water Reactors with respect to achieved uranium utilization rates. The assumptions and method of approach are discussed. The data is presented in several ways. Historical specific energies have been determined for all operating cycles for each nuclear reactor having completed at least one cycle prior to April 1979. In addition, the data has been aggregated to illustrate the following: (1) performance histories of BWRs and PWRs, (2) reactors with a MWe rating above and below 800 MWe, (3) reactors which have operated for five cycles or more, and (4) chronological experience of annual discharges