Conceptual design of a mixed moderator spectral shift reactor for flexible plutonium utilization

It is feasible to adjust the Plutonium consumption to suit the Plutonium supply and demand balance by changing the neutron spectrum of a reactor. The Mixed Moderator PWR changes the neutron spectrum by changing the moderator of a PWR from light water to heavy water or a combination of both and also by slightly changing of ratio of the moderator to heavy metal atoms. Therefore, using basically the same PWR hardware, the required Plutonium inventory and Plutonium consumption can be changed by a factor of three and twice, respectively. In addition, the introduction of the MPWR with a high conversion ratio can be used as an active Plutonium storage reactor during the period before Fast Breeder Reactors are introduced and, therefore, Plutonium recycling program can be based on the so called ''no Plutonium stockpile'' principle. (author)