C. Rubbia’s hybrid plant concept: a preliminary technical and economic analysis

The long term development of nuclear energy depends, inter alia, on the ability to use the abundant fertile materials (238U and/or thorium) and on an accepted management of the long-lived radioactive wastes. In order to meet both these objectives, C. Rubbia has presented a new version of an old concept: the hybrid reactor where a subcritical reactor is fed with neutrons produced by spallation. In his concept, the reactor is a molten lead cooled fast reactor, which can use either the uranium or the thorium cycle, and burn the minor actinides and some fission products. The present work is a preliminary and partial technical and economic analysis of the reactor part of C. Rubbia’s proposal as they were set forth in a French Parliamentary audition in November 1996. The technical conclusions are that many of the design options proposed are not optimum and the uncertainties important, which is not particularly surprising at this stage of the concept. The economic ‘guesstimate’ yields a cost per kWh anywhere between one and two times that of a modern light water reactor, which is in contradiction with C. Rubbia’s claims (half the cost!), but in a range which warrants more conceptual work before drawing any conclusions. Alternative design concepts are suggested.