Difference between revisions of "Problem set 2"
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Latest revision as of 10:01, 9 July 2012
Mother daughter Relations and Equilibrium
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1:
One kg of fresh and dry thorium nitrate, Th(NO3)4, is produced from a natural occurring thorium containing ore.
- Calculate the rate 232Th and 228Th disintegrates, and explain why the rate of disintegration is approximately equal for both of the thorium isotopes.
- What is the weight of 228Th in the thorium nitrate?
- 228Ra separated from a one year old thorium nitrate can be placed on a column to make an isotope generator. The chemical yield for this process is 90%. How much amount of thorium nitrate is required to make the column, if 228Ra disintegrates with 10 000Bq?
- At which rate will 224Ra disintegrate 3 days after the column is made?
- Are there any other radionuclides present at a noteworthy amount (more than 100Bq)?
2:
One gram of natural uranium is purified to contain no other elements than uranium at the time t equals 0.
- Which radionuclides are present at t=0?
- What are their respective rates of disintegration?
- Which radionuclides are present at t=25,5h?
- What are their respective rates of disintegration?
- Which radionuclides are present at t=24d?
- What are their respective rates of disintegration?
- Which radionuclides are present at t=1.0a?
- What are their respective rates of disintegration?
- Which radionuclides are present at t=10.0a?
- What are their respective rates of disintegration?
3:
A given amount of alum shale contains 10 grams naturally occurring uranium.
- What amounts of radium in Bq and grams does the same alum shale contain?
- Which amount of 210Pb is present?
- 210Pb is a weak beta emitter, but is still very toxic in large amounts. Why is it so?
4:
Some radionuclides have a major application in medicine. For practical reasons it is advantageous if these can be produced with the help of an isotope generator.
- Explain how an isotope generator may impact practical conditions.
- Which of the following medical radionuclides can be produced by an isotope generator? 67Ga, 68Ga,64Cu, 82Br, 89Sr, 90Y, 123I, 131I, 177Lu,201Tl, 211At, 212Pb, 211At, 223Ra.
- In heart examination 201Tl is used in amounts of 100MBq by intravenously injection of the radionuclide. Which chemical amounts does this equal?
- Thallium is a potent rat toxin, why do patients survive these examinations?
5:
A daughter nuclide is eluted from a 100 MBq 44Ti source in a column.
- How long does it take before 50 MBq of the daughter can be eluted from the system?
- At this point, how much does the respective amounts of nuclides weight?
6:
Minerals containing thorium emits strong gamma radiation, without any of the involved thorium isotopes emitting gamma.
- Explain where the gamma radiation is coming from.
- Which thorium isotopes exists in natural thorium, and what is the relation between them?
- As a rule of thumb, it is said equilibrium is achieved after 10 halfe-lives. How much time must pass before equilibrium is reached throughout the entire chain of natural occurring thorium and uranium?
7:
100 grams of fresh metallic thorium is prepared from naturally occurring thorium containing minerals.
- What is the rate of disintegration?
- How many grams of 228Th are present?
- How many grams of 229Th are present?
- What is the total activity of the metallic thorium 7.2 days after it was made, and how is the branching ratio between alpha and beta radiation?
8:
A source of 10 000 Bq from the very long lived 194Hg is used to produce 194Au. Assume 100% efficiency in the production process.
- How long does it take until 1000 Bq of the daughter can be extracted from the mother?
- How long does it take until 7500 Bq can be extracted?
9:
The radionuclide 211At is planned to be used for medical purposes. It has a branching of 58% EC and 42% α.
- Explain why you get a long lived daughter from one of these branches.
- What is the weight of At in a 50 MBq 211At sample?
- What is the rate of disintegration one week after the sample was made?