(526a) Practical Actinide Partitioning

Actinide partitioning is a concept for removing all alpha emitters from fuel cycle wastes, particularly during fuel reprocessing and refabrication. It has been studied as a waste management concept, but may have more value as a safeguard feature to make recycled plutonium unsuitable for weapons manufacture. The minor actinides in spent fuel also have some value as fuel extenders, particularly in fast reactors.

Practical actinide partitioning is based on the use of well established reprocessing unit operations. These include solvent extraction, distillation, low-temperature oxidation, and process stream recycle to produce partitioned high, medium, and low-level wastes. High temperature unit operations (e.g., molten salt and/or molten metal processing) are neither needed nor desirable for this application where gaseous emissions must be carefully controlled.

Actinide partitioning flowsheets are presented that incorporate Urex, Truex, and An/Ln separations. Alcolex (alcohol extraction) and cerium oxidation are used to manage solvent degradation products and enable the production of thermodynamically stable waste forms. Since cross-contamination of solvents will inevitably result, solvent selections must be limited to those which are compatible with each other and whose degradation products can be managed through a recycle process including cerium oxidation of residuals and alcohol extraction. Working together, these operations can produce an aqueous phase that can be recycled to Urex without the buildup of degradation products in the solvents.

The immediate conversion of partitioned, high-level liquid waste to a glass waste form eliminates the need for the addition of non-volatile neutron poisons. As a consequence, the solvent extraction operations subsequent to uranium removal can be substantially reduced in size. Integration and optimization strategies are reviewed and discussed.