Plutonium processing step-reaction

These processes do not operate independently for example, the behavior of plutonium in step 3 will be greatly dependent on the species formed as a result of solution-phase reactions in step 2. However, from a chemical standpoint, we have found that consideration of these processes individually is a useful aid to understanding the transport of plutonium in a ground-water system. 

Reduction and oxidation (redox) steps are major process steps in the Purex process. Use is made of redox reactions to alter the valency of plutonium, uranium or neptunium with the object of producing these metals with a high degree of purity. 

In the dissolution step, the fuel pieces are dissolved in near boiling 10 M HNO3. This step, which takes a few hours, dissolves the uranium, plutonium, and fission products, leaving the cladding to be recovered. The Kr and Xe are recovered from the off-gas of steam, air, and NO. The chemical reactions for the dissolution of uranium involve processes like... 

The Purex process is presented schematically in Figure 21.11, where the solvit extraction steps are within the dotted frame. Three purification cycles for both uranium and plutonium are shown. High levels of beta and gamma activity is presort only in the first cycle, in which > 99 % of the fission products are separated. The principle of the first cycle is shown in Fig. 21.13. The two other cycles are based upon the same chemical reactions as in the first cycle the purpose is to obtain additional decontamination and overall purity of the uranium and plutonium products. Each square in Figure 21.13 indicates a number of solvent extraction stages of the particular equipment used pulsed columns, mixer-settlers, etc. (see Appoidix A). 

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