Use of thorium in Boiling Water Reactors

Abstract

The potential for use of 232Th as a fertile material in Boiling Water Reactors is reviewed. The use of ThO 2 for local power flattening in heterogeneous Boiling Water Reactors and its application to future fuel for the Dresden Nuclear Power Station is discussed. This method of flattening provides a number of advantages over simple enrichment variation. Supporting experimental measurements are reviewed. The nuclear aspects of 235U - 232Th, Pu- 232Th and 235U- mixed 232Th 238U fuels are discussed for large BWR application. It is concluded that 235U- 232Th fuels are of interest because of the potential for achievement of long exposures. Mixed 238U- 232Th fertile isotopes provide interesting and possibly useful trends in resonance capture and conversion. From the nuclear standpoint plutonium is feasible as an initial or make-up fuel for a thorium cycle. The pros and cons of use of 232Th as compared to 238U are discussed. It is concluded that sufficient economic and technical information is not presently available to make a conclusive long-term choice between these fertile isotopes and, therefore, design provisions for flexibility of future optimal utilization of either fertile material are desirable for thermal reactors which are built in the next few years.