Latest revision as of 13:42, 10 April 2012

Mother daughter relations and equilibrium

1: One kg of fresh and dry thorium nitrate, Th(NO₃)₄, is produced from a naturally occurring thorium containing ore.

1. Calculate the rate ²³²Th and ²²⁸Th disintegrates.
2. Explain why the rate of disintegration is equal for both of the thorium isotopes.
3. What is the weight of ²²⁸Th in the thorium nitrate?
4. 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?
5. At which rate will ²²⁴Ra disintegrate 3 days after the column is made?
6. 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 at the time t equals 0.

1. Which radionuclides are present at t=0?
2. What are their respective rates of disintegration?
3. Which radionuclides are present at t=25,5h?
4. What are their respective rates of disintegration?
5. Which radionuclides are present at t=24d?
6. What are their respective rates of disintegration?
7. Which radionuclides are present at t=1.0a?
8. What are their respective rates of disintegration?
9. Which radionuclides are present at t=10.0a?
10. What are their respective rates of disintegration?

3: A given amount of alum shale contains 10 grams naturally occurring uranium.

1. What amounts of radium in Bq and grams does the same alum shale contain?
2. Which amount of ²¹⁰Pb is present?
3. 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.

1. Explain how an isotope generator may impact practical conditions
2. 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.
3. In heart examination ²⁰¹Tl is used in amounts of 100MBq by intravenously injection of the radionuclide. Which chemical amounts does this equal?
4. 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.

1. How long does it take before 50 MBq of the daughter can be eluted from the system?
2. 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.

1. Explain where the gamma radiation is coming from.
2. Which thorium isotopes exists in natural thorium and what is the relation between them?
3. As a rule of thumb, it is said equilibrium is achieved after 10 halve lives. How much time must pass before equilibrium is reached throughout the entire chain of natural occuring thorium and uranium?

7: 100 grams of fresh metallic thorium is prepared from naturally occurring thorium containing minerals.

1. What is the rate of disintegration?
2. How many grams of ²²⁸Th are present?
3. How many grams of ²²⁹Th are present?
4. 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.

1. How long does it take until 1000 Bq of the daughter can be extracted from the mother?
2. 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.

1. Explain why you get a long lived daughter from one of these branches.
2. What is the weight of At in a 50 MBq ²¹¹At sample?
3. What is the rate of disintegration one week after the sample was made?