Reactor Physics Assessment of Potential Feasibility of Using Advanced, Nonconventional Fuels in a Pressure Tube Heavy Water Reactor to Destroy Americium and Curium

Abstract

Lattice physics and core physics studies have been carried out to investigate the reactor physics feasibility of destroying americium (Am) and curium (Cm) using special target fuel bundles in blanket fuel channels in a heterogeneous seed-blanket pressure tube heavy water reactor (PT-HWR) core fueled primarily with natural uranium. Results indicate that it should be feasible to achieve net-zero production of Am in a single PT-HWR core using 10 to 16 dedicated blanket channels containing Am-based target bundles while only one dedicated blanket channel would be required for achieving net-zero production of Cm. While the use of target blanket fuel bundles with fuel elements made of Am or Cm mixed with thorium (Th) in oxide form ((Am,Th)O₂, (Cm,Th)O₂) is expected to be suitable for transmutation purposes, the use of fuel elements made of pure americium oxide, especially those in the form of AmO_1.55, may not be suitable for transmutation purposes because of potential issues with fuel melting under high-power operations or postulated accident scenarios. The potential to achieve net-zero production of Am and Cm in a single thermal-spectrum reactor, such as a PT-HWR, could help eliminate the need to build and qualify a deep geological repository (DGR) capable of storing minor actinides for a long time (>1 million years). At the very least, the size and/or number of DGRs required for storing radioactive waste could be reduced significantly. Thus, destroying Am and Cm in PT-HWRs could be regarded as a viable solution to the perceived problem of nuclear waste and may help improve public acceptance of the use of nuclear energy. In addition, it may be possible to apply a similar approach for destroying MAs in other Generation III+ (Gen-III+)/Generation IV (Gen-IV)/small modular reactor (SMR) technologies.

Keywords:

• Pressure tube heavy water reactor
• transmutation
• americium
• curium, thorium

Acknowledgments

The authors thank the following Canadian Nuclear Laboratories (CNL) staff for their assistance: G. W. R. Edwards, P. Pfeiffer, S. Pfeiffer, F. P. Adams, S. Golesorkhi, J. Pencer, T. Wilson, A. Siddiqui, and S. Shim. This study was funded by AECL, under the auspices of the Federal Nuclear Science and Technology Program. This work was supported by CNL.