Considering points in the presentation
[Team A]
1. Uranium is known to have +4, +6 oxidation states. What is the oxidation state (number) of uranium in ? How can you interpret (explain) this oxidation state?
2. You have dissolved into nitric acid. Write down the chemical reaction of this dissolution.
3. You extracted uranium from the nitric solution by formation of ADU. What is the chemical formula of ADU? And what is the chemical reaction of ADU formation?
4. You oxidized ADU in the air to get uranium oxides. Write the chemical reaction of ADU oxidation into .
5. When you oxidized ADU in the air, you finally obtained . Can you explain why you got instead of or ?
[Team B]
1. The product of uranium from the ore is called yellow cake because it takes a yellow color. They say the yellow cake is . What is your opinion on their explanation?
2. You reduced to in hydrogen. How much the weight of the sample has to be decreased? Can the weight change of your specimen be explained by this reduction reaction?
3. was reduced to in hydrogen gas. You can reduce up to ; but, you cannot reduce it up to U metal. Why? Then, how can we make U metal from uranium oxide?
4. is known to take an orthorhombic structure. What the orthorhombic structure looks like?
5. takes a fluorite structure. Draw the fluorite structure. From the XRD measurements, you could obtain a lattice parameter of that you had prepared. Calculate the X-ray density of specimen that you made, and compare it with the values in the literature.
[Team C]
1. Explain the principles of solvent extraction. Solvent extraction is a key technology in reprocessing of spent fuels in the nuclear industry (e.g., PUREX process). Of course, it is not only nuclear industry that uses solvent extraction technology. Can you give another examples (processes) that use the solvent extraction technique?
2. You have extracted uranium from the nitric acid solution using a solvent extraction technique. Write the chemical reaction of uranium extraction from the aqueous solution to the organic solvent using TBP.
3. The extraction efficiency (or correctly speaking, distribution coefficient) of uranium strongly depends on the nitrate concentration in the aqueous solution. Can you explain this dependency of distribution coefficient by the uranium extraction (using TBP) reaction of the question 2?
4. The distribution coefficient of Sr is quite low comparing to that of uranium in the solvent extraction using TBP. Is this big difference in distribution coefficients beneficial to the reprocessing of spent fuels? Is it also beneficial in the reprocessing of spent fuels that there is a strong dependency of distribution coefficient of uranium on the nitrate concentration of the solution? Why?
[Team D]
1. Both plutonium and uranium can be extracted to the solvent from the nitric solution containing dissolved spent fuels. How can you separate Pu from the solvent that contains both Pu and U?
2. Explain real time, dead time, live time in detail.
3. Pulse shape spectrum is used in detecting alpha rays in the solution. In the spectrum obtained in the alpha ray measurements, what corresponds to the channel numbers? (or what corresponds to the horizontal axis?)
4. What is the detection efficiency of a detector? The detection efficiency of alpha rays is said to be 100%, while that of gamma detector is low. Why the efficiency of the alpha-ray detector is close to 100%? And why the efficiency of the gamma ray detector is low comparing to the alpha-ray detector?
5. Someone brought an ore rock containing uranium with many impurities such as Fe, Ni, Cr, etc. He wants to extract uranium from the rock. Can you construct a series of chemical processes where pure uranium oxides can be delivered to him from the rock?