1-, remarkable presentation, just to add on I would recommend the physician if he/she can consider treating the patient with hyper baric oxygen in order to increases oxygenation to the tissue, improve

1. What does the PUREX acronym stand for?

2. PUREX extraction is a reprocessing technology for used nuclear waste. What is it designed to recover from the used reactor fuel?

3. Where (US Nat Lab) and when did the PUREX originate?

4. Typical light water reactor fuel is UO2. What is in the used, neutron-irradiated (“spent”) nuclear fuel? List the main constituents!

5. Used fuel is dissolved in nitric acid. Why in HNO3 and not HCl or H2SO4?

6. Write the chemical reaction for dissolution of uranium and plutonium dioxides in HNO3 into the relevant nitrate species of Pu and U!

7. The principle of solvent extraction is a distribution of species between two immiscible liquid phases. This two-phase mixture is vigorously agitated to reach the partition equilibrium between contacted phases faster. In PUREX, aqueous phase is the nitric acid solution of the spent fuel, organic phase is the TBP (tributyl phosphate) diluted with alkane (kerosene). What concentration (vol. %) of TBP is used in the PUREX process?

8. What species are extracted into organic phase and what metal species remain in the raffinate (=the post-extraction aq phase)?

9. What is the chemical equations for extractions of Pu and U with TBP?

10. Write the expression for the Pu+TBP extraction equilibrium!

11. Separation funnels are used only in the research or teaching labs - list 3 devices used for extraction in reprocessing scale.

12. What are a) advantages and b) disadvantages of the PUREX extraction?

13. What is the distribution ratio for Pu ratio, if the analyst measured 1200 cpm/mL for the organic phase and 100 cpm/mL for aqueous phase? Assume the same counter (detection efficiency), negligible background count rate and Pu in the counting samples were purified from the other radionuclides.

14. What is the separation factor for Pu/Am, if for Pu the analyst measured 200 cpm/mL for the organic phase and 100 cpm/mL for aqueous phase, while for Am it was 100 cpm in organic phase and 500 cpm in aqueous phase? Assume the same counter (detection efficiency), negligible background count rate and both Pu and Am in their counting samples were purified from other radionuclides.

15. In the end of extraction process (when agitation ended), what does happen with U and Pu? Propose how to strip them from organic phase into a fresh aqueous phase – i.e., what aq phase? Water or nitric acid or concentration? What then will be the formulas of Pu and U species in the stripping aq phase? Hint: Pu(IV) must be stripped as the first (to get it stripped, a reductant to make it Pu(III) is needed), then U is stripped as the second. When they are converted back to dry oxides, they may be mixed into a new mixed oxide U(Pu)O2 fuel, where Pu (fissile isotope) will stand instead of U-235.