Recent Chemical Research Projects in Pyrochemistry

摘要

The purpose is to create, define parametric limits for, and transfer to the Pyrochemical Development group a pyrochemical (electrochemical) process for the recovery of spent anodes from plutonium electrorefining. The basis for this endeavor is the idea of modifying the character of spent anodes to obtain and maintain a liquid state during continued electrolytic depletion of plutonium. There are many alloying agents or combinations of alloying agents which could be added. The one chosen for the initial work was gallium because of its low melting point and low vapor pressure. From the Pu-Ga phase diagram, a composition of approximately 78 atomic percent gallium (50 weight percent) was chosen for the first solubilization experiment. One hundred grams each of spent anode and gallium were heated under 490 grams of NaCl-KCl-MGCl sub 2 to 740 C, held for one hour and stirred for one hour. Examination of the microstructure of the resultant cooled mixture indicated that 90% of the surface was a single phase containing near-equal concentrations of plutonium and gallium. The microstructure also contained inclusions of various impurities. The probability of anodically depleting the mixture of plutonium and gallium down to a very low level is high, based upon the electro-chemical potentials for plutonium and gallium in chloride systems. This work has the potential to provide a single step process for the removal of plutonium from spent anodes to the level where the remaining Ga-rich material can be discarded. Reuse of the Ga-rich material is also a possibility. The plutonium should be recoverable as a metal phase. (ERA citation 10:046166)