Recovery of Fissile Materials from Wastes and Conversion of the Residual Wastes to Glass

A new process has been invented that converts complex wastes containing fissile materials into a chemical form that allows the use of existing technologies (such as Purex and ion exchange) to recover the fissile materials and convert the resultant wastes to glass. Potential feed materials include (a) uranium fissile wastes, (b) miscellaneous spent nuclear fuel, and (c) plutonium scrap and residue. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, and organics.

The process consists of three major sets of process operations. During the first set of operations, the feed is dissolved into molten lead-borate glass and then converted to a boron oxide (B₂O₃) fusion melt. During this process, (a) the organics and metals are oxidized and (b) the halides and noble metals are separated from the melt. During the second set of operations, the cooled fusion melt is dissolved into nitric acid, and the uranium and plutonium are recovered from the acid using standard aqueous separation processes such as Purex and ion exchange. During the third set of operations, standard waste vitrification processes convert the residual waste to borosilicate glass. The B₂O₃ can be recovered and recycled at several locations within the process.