1. A radioactive source emits 4200 beta particles in a time of 2 minutes.
Calculate the activity of the source.
2. Find the absorbed dose if 2 mJ of energy from radiation is absorbed by
(a) 40 kg of lead
(b) 8 kg of steel
3. How much energy would have to be absorbed by 0.3 kg of aluminium to give an absorbed dose of 6 mGy?
4. A shielding material of mass 25 kg absorbs 400 J of energy from radiation in 16 days.
Calculate the absorbed dose and the absorbed dose rate.
5. What would be the values for absorbed dose and absorbed dose rate in the following circumstances?
(a) 200 kg receives 200 kJ of energy every 100 hours.
(b) 6 kg absorber accepts 24 MJ in one year.
6. An absorbed dose of 200 µGy is caused by thermal neutrons (WR = 3).
What is the equivalent dose?
7. A physics teacher is irradiated by alpha particles when using a 185 kBq source .
(a) Calculate the equivalent dose received if the teacher has a mass of 6O kg and the total energy absorbed is 9 x 10-7 J.
(b) Calculate what the equivalent dose would be if all the ionisation took place in the teacher's hand which has a mass of 0.5 kg?
8. A nuclear fuel process worker receives the following: 2O µGy from fast neutrons, 1O µGy from thermal neutrons and 25 µGy from gamma radiation.
Calculate the total equivalent dose?
9. A research physicist receives a total of 100 µGy of gamma radiation and 10 µGy of thermal neutron radiation during an experiment lasting 10 hours.
Calculate the total equivalent dose rate.
10. A reactor worker receives a total of 8 mSv after working for forty weeks at 20 hours a week in the radiation zone.
What was the equivalent dose rate?
11. Two metres from a point source of radiation the equivalent dose rate is 800 µSv h-1 .
Calculate what the equivalent dose rate would be at
(a) 4 metres and
(b) 10 metres from the source?
12. For the same source, at what distance would the equivalent dose rate be 5O µSv h-l ?
13. A radioactive source produces a count rate of 1024 c/s. After 6 mm of lead shielding is used the count rate falls to 128 c/s.
What is the half-value thickness of the source?