A possibility of highly efficient uranium utilization with a pebble bed fast reactor

In order to achieve highly ecient natural uranium utilization with a once-through fuel cycle, an idea of a pebble bed type fast reactor is investigated. The e€ective multiplication factor of 1.049 is obtained in the case of zero radial buckling for an optimum fuel velocity. The discharged fuel burnup becomes 439 GWd/tHM for mean power density of 50 W/cc, which is equivalent to the utilization of 457% of natural uranium.