Security and non-proliferation assessment of breed-and-burn systems - 5270

One argument heard from advocates of spent fuel recycle is that the once-through cycle does not use uranium efficiently. However, the conventional closed fuel cycle requires reprocessing of spent fuel and fresh fuel re-fabrication: activities that present opportunities for diversion or theft of plutonium or other weapon-usable isotopes. Recently a number of once through breed-and-burn system concepts, such as TerraPower, have received attention. These systems can operate on low-enriched uranium and have the potential to improve uranium utilization compared to the current reactor fleet by increasing the in-situ production and fission of plutonium. By improving uranium utilization without the need to reprocess, such systems could be attractive alternatives to closed fuel cycles, and may gain the support of security experts concerned about the risks of closed fuel cycles. However, as TerraPower has found, development of a long-lived core that doesn't require fuel rearrangement has turned out to be a technically very difficult task. Instead, fuel shuffling is needed. The price that may need to be paid to increase once-through uranium utilization is more manipulation of fuel than is typical for light-water reactors. While some may see this as a nonproliferation disadvantage, it may be an acceptable tradeoff for avoiding reprocessing and recycle. Significant safety issues are inevitable in breed-and-burn systems because their successful performance generally requires exceeding existing safety limits with regard to fuel burnup, irradiation damage to cladding and structural materials, power peaking and reactivity coefficients. This paper analyzes the comparative security risks of once-through breed-and-burn reactors and closed fuel cycle systems