Abstract
Mixed uranium plutonium oxide (MOx) pellets are a potential candidate wasteform for plutonium disposition in a GDF. However, to manufacture MOx pellets suitable for disposal, homogenised powder feeds must be densified by a sintering process. This is an energy intensive and time-consuming process. Flash Sintering (FS) is an innovative technique in which an electric field is applied to the sample during the sintering process. It offers a more efficient and robust way to densify ceramic-containing nuclear material for disposal.
The FS process requires significantly lower firing temperatures. It may therefore offer safety improvements when immobilising unique or problematic waste streams, due to the retention of volatile but long-lived minor actinides such as americium oxide. These would normally vaporise out of the MOx pellet during the high temperatures and long hold times in conventional sintering.
We report the successful application of controlled current rate AC-FS flash sintering on both UO2 and CeO2 surrogate nuclear material for both fuel and waste applications, together with the microstructural evolution of pellets produced using both conventional (CeO2) and FS (CeO2 and UO2). These results demonstrate the possibility of forming different microstructures as a function of current density, in a fraction of conventional processing time. Future opportunities exist for expanding this work to the demonstration of FS on mixed CeO2 and UO2, as well as zirconia and neutron poison-doped materials for waste management applications.
The FS process requires significantly lower firing temperatures. It may therefore offer safety improvements when immobilising unique or problematic waste streams, due to the retention of volatile but long-lived minor actinides such as americium oxide. These would normally vaporise out of the MOx pellet during the high temperatures and long hold times in conventional sintering.
We report the successful application of controlled current rate AC-FS flash sintering on both UO2 and CeO2 surrogate nuclear material for both fuel and waste applications, together with the microstructural evolution of pellets produced using both conventional (CeO2) and FS (CeO2 and UO2). These results demonstrate the possibility of forming different microstructures as a function of current density, in a fraction of conventional processing time. Future opportunities exist for expanding this work to the demonstration of FS on mixed CeO2 and UO2, as well as zirconia and neutron poison-doped materials for waste management applications.
| Original language | English |
|---|---|
| Title of host publication | Waste Management Symposium 2022 |
| Publication status | Accepted/In press - 14 Jan 2022 |
