Measured proof of breeding of the light water breeder reactor

Proof of self-sustaining breeding in the light water breeder reactor (LWBR) would mean that this proven pressurized water reactor (PWR) could provide our nation with an energy option from plentiful thorium about 50 times larger than that provided by current commercial reactions. Assay measurements to date of expended fuel elements from the LWBR indicate successful breeding. Bettis Atomic Power Laboratory designed and built a LWBR under technical direction of the US Department of Energy's Office of Naval Reactors. The core produced 60 MW(e) in the nation's first large-scale nuclear power plant, Shippingport, which was operated by Duquesne Light Company to provide electric power to the Pittsburgh area. The LWBR core operated from 1977 to 1982 for about 29,000 equivalent full-power hours. To date, more than 350 rods from eight fuel modules have been assayed. The EOL fissile content of these modules was deduced from assay results and compared with calculated loadings. LWBR breeding performance was estimated based on the results from assay of the first eight modules. The ratio of the EOL core fissile content to the initial value is called the fissile inventory ratio (FIR). An FIR >1.0 indicates breeding. Allowing for an estimated fuel reprocessing loss of 0.5%, FIR >1.005 would provide a self-sustaining fuel cycle. The authors presently estimate that FIR lies between 1.012 and 1.015, compared to a predicted value of 1.0135