Plutonium residue recycle processes

Process Schematic. A schematic showing our main production sequence and our present plutonium residue recycle streams is seen in Figure 10. The oval-shaped steps, representing the recycle streams, are as follows ... 

Primary waste generation is small because of the high density nature of the fused salt operations. Nearly all primary waste residues show excellent potential for recycle. (The present main processing sequence for plutonium does not include significant reagent and residue recycle). 

The skull metal and oxide are first completely burned to oxide by heating in air to 400-500°C. The plutonium metal spontaneously burns and is collected as a green Pu03 powder. This oxide is recycled back as feed for Direct Oxide Reduction. This process is normally 100% efficient with only a small plutonium residue showing up in items such as clean-up rags. 

Spent anode residues from electrorefining (which contain approximately 20-30 percent of the plutonium fed to the process) are either recycled back to electrorefining, or, if high enough in impurities, are oxidized and sent to oxide dissolution. The spent salt is sent to aqueous dissolution (see Figure 1). 

Recent process development efforts have been devoted to more expeditious and less costly pyrochemical reprocessing of residues created by the metal preparation and purification process. We intend to establish an internal recycle which yields either reusable or discardable residues and recovers all plutonium for feed to the electrorefining purification system. This internal recycle is to be performed in a more timely and less costly operation than in the present reprocessing mode. 

In addition, we are evaluating problems in the areas of process and equipment design have been evaluated. Most recent efforts are concerned with the recovery and recycle of plutonium values in the residues. 

This document will summarize our present main production sequence and discuss how it was arrived at. It will then discuss the status of our present recycle of plutonium values in residues. Third, it will discuss our proposed recycle of all plutonium in residues. Finally, it will discuss our goal of a fully integrated process sequence where plutonium and salt residues are recycled through the production sequence. 

As a result of following the pyrochemical recycle route rather than the aqueous waste processing route, the plutonium values in the residues can be returned very expeditiously to the main process sequence. The form of the plutonium is metal, which is most desirable from a production standpoint. 

In order to achieve this goal of a fully integrated process sequence, a concerted research and process development effort must take place. Present R D efforts are devoted to the development of cost-effective pyrochemical processes for the recycle of plutonium in residues. Future efforts will be aimed at the recycle of reagents in each individual process. The objectives of the recycle are to produce plutonium metal which can be further purified, and to generate small volumes of residues which can be discarded or recycled. 

Stripping of the residual plutonium in the WS-2 Column with a small volume of 0.1M HNO3-O.IM HF solution. The resulting plutonium product is suitable for direct recycle to the mainline PRF TBP extraction process (Figure 1). 

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