Tuesday, March 6, 2018

CHEM 418 Nuclear Chemistry Winter 2018 Exam 3


Assigned: 6-Mar-18                                                                  
1st Due Date: 10-Mar-18
2nd Due Date:  13-Mar-18             
                                                           
Lecture 11:  Speciation
Lecture 12:  Uranium chemistry
Lecture 13:  Neptunium chemistry
Lecture 14:  Plutonium chemistry
Lecture 15:  Americium and Curium chemistry
Lecture 16:  Chemistry in reactor fuel
Lecture 17:  Separations
Lecture 18:  Application of Nuclear Material
Lecture 19:  Nuclear Forensics


Use lecture notes, textbooks, Chart of the Nuclides, Table of the Isotopes, and web pages.  Use the chart of the nuclides as your primary dataset for isotope half-life.   Show your work or references on a separate page and save electronically.  Submission of the work is not required for the 1st due date.  Please use 3 significant digits for your answers.  For scientific notation please use X.XXEX (i.e, 1230 as 1.23E3)


Office hours for Exam 3 will be on Friday 9 March from 1030 to 1200 in Bagley 303A.

40 comments:

  1. My exam has been submitted on canvas

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  2. I have submitted the exam.

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  3. Exam was submitted via email, thank you!

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  4. thanks for the comments and quizzes. I will answer posted questions later tonight. If you post a question you can submit the exam after the question has been answered.

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  5. Professor, within what deviation from your answer for 4.5 (a suitable range of wavelengths for the titration of trivalent Americium) will our answers be considered acceptable? Thank you for your time.

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    1. Also, does the 10kg mass in question 6.4 refer to pure 237-Np, or to an NpO2 target? Are we using pure 238-Pu or PuO2 in the 250W application? Thanks again for your time.

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    2. Are we constantly irradiating the sample, or for a fixed amount of time. If the latter, what is that amount of time?

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    3. I also don't know what compound we are irradiating? In lecture it said 238-Pu was made starting from 235-U. Are we allowed to assume we're starting from 238-Np and not go through the whole chain? Or like it says in lecture 18 can we assume we're irradiating a NpO2/aluminum matrix?

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    4. for the wavelength 20 to 50 nm range would be suitable

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    5. using 237Np as the target is acceptable. From lecture 18 238Pu is produced with 237Np for an application purpose.

      The application uses 238PuO2, but you make 238Pu in the reactor, not the oxide.

      You should just find the rate of 238Pu formation. You can calculate how much you produce in a second, then use that to find the amount of time needed to produce the needed amount.

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    6. This comment has been removed by the author.

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    7. Thank you, professor. I have resent my first submission with revised answers to the questions we discussed (6.4 and 6.5) by email.

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  6. Exam submitted via email and canvas.

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  7. I have submitted the exam on canvas and by email

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  8. I am confused about question 6 as well. For 6.2, do we use the W/g of 238-PuO2 listed in the slide (0.418 W/g) or the actual energy output of devices listed (0.411 W/g [slide 10, ppt 18a] or 0.37 W/g [slide 11, ppt 18a]? Then how do we calculate the length of time of irradiation without the cross section? I thought I would use a decay constant and neutron flux to determine the effective decay constant which could in turn be used to calculate the activity, and then use the number of decays per second and fission probability to determine how long it would need to be irradiated to reach the mass determined in 6.2. But to do that I would need the cross section, which is not given. So I'm unsure how to solve this problem?

    Which lecture/resource is this explained in?

    Sorry for posting so close to the deadline. At this point I'd just like to know so I can fix it for the resubmission.

    Thank you for your time,
    -Sarah

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    1. Either value would work, you would need to adjust for the oxide form. You can use 0.418 W/g in this case.

      For the cross section, you can look up the values from the reading on https://canvas.uw.edu/courses/1190316. You can also find all the cross section data at https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html

      The chart of the nuclides as 169 barns as the neutron capture cross section for 237Np. Other values in the literature do vary from this.

      You can calculate the formation rate from information provided in lecture 3.

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    2. Thank you so much professor! I have resubmitted the exam on canvas with the corrections.

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  9. Quiz Submitted on Canvas. A lot of the boxes wouldn't populate again so I just answered them in text boxes inside the document.

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  10. quiz submitted. I'm in the same boat as Sarah. I listened to the canvas conference this morning but I didn't take good enough notes for number 6 and I was pressed for time today.

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  11. Quiz submitted. Question 6 was a bit confusing.

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  12. I submitted the exam via email and canvas. I was also confused with question 6.4. Without a cross section, I was not completely sure how to proceed. Could you provide an explanation or a resource for understanding this question. Thank you.

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    1. Thank you for the explanations Professor. They were helpful and I have made the necessary corrections to question 6. I have resubmitted the exam by email and on canvas.

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  13. Thanks for the comments. I will post the answers later tonight.

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  14. Exam was submitted on time, I forgot to comment about it until now though.

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  15. I resubmitted the assignment on canvas after I incorporated your explanations on how to answer question 6.

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  16. Quiz resubmitted via email with corrected/finished #4. Thank you.

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  17. The Exam 3 corrections have been submitted on canvas.

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  18. Exam 3 corrections have been submitted via email

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  19. I have sent my 2nd submission of Exam 3 with corrections by email.

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  20. Resubmitted quiz 3 with corrections on canvas.

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  21. Revisions submitted via email with attached picture of hand written work.

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