Irradiation & contamination

Some atoms emit radiation.

Why do scientists sometimes change the model used to describe the structure of the atom?

Tick () one box.

When radioactivity was discovered, the dangers of radiation were not known.

Some scientists were irradiated and contaminated while working with the radioactive materials.

Describe the difference between irradiation and radioactive contamination.

Polonium-210 was one of the first radioactive elements to be discovered.

Polonium-210 (Po) decays into lead (Pb).

Complete the nuclear equation for polonium-210.

Polonium-210 has a half-life of 138 days.

A sample of polonium contains 256 000 atoms.

Calculate the time taken for the number of polonium-210 atoms to reach 16 000.

A sample of polonium contains equal numbers of polonium-209 atoms and polonium-210 atoms.

Polonium-209 has a half-life of 125 years.

Polonium-210 has a half-life of 138 days.

Explain how the activity of polonium-209 compares with the activity of polonium-210 in this sample.

A teacher investigated the radiation emitted by two different radioactive sources, A and B.

Figure 14 shows a radiation detector positioned near one of the radioactive sources.

The teacher measured the count rate at different distances for each radioactive source.

Figure 15 shows the results.

Explain how Figure 15 shows that Source A only emits alpha radiation.

Figure 15 can not be used to determine if Source B emits beta radiation or gamma radiation.

Explain how an absorbing material could be used to show which type of radiation is emitted by Source B.

The teacher took safety precautions during the experiment.

Suggest one safety precaution the teacher would have taken to reduce the radiation dose the teacher received.

Suggest one safety precaution that the teacher would have taken to avoid becoming contaminated.

Figure 16 shows how the number of atoms of a radioactive element in a sample varied with time.

Activity is the rate at which a source of unstable nuclei decays.

Determine the activity of the radioactive sample at 300 seconds.

Give the unit.

Some isotopes emit nuclear radiation.

Carbon-12 and carbon-14 are both isotopes of carbon.

Complete the sentences.

Choose answers from the box.

The nucleus of a carbon-12 atom and the nucleus of a carbon-14 atom have the

same number of.

The nucleus of a carbon-12 atom and the nucleus of a carbon-14 atom have a

different number of.

Different radioactive isotopes have different half-lives.

What does ‘half-life’ mean?

Tick (✓) one box.

Table 2 shows the half-life of some different isotopes of carbon.

Which isotope is the least stable?

Tick (✓) one box.

Workers in nuclear power stations must be aware of nuclear irradiation and radioactive contamination.

Draw one line from each term to an example of the term.

Why are workers required to walk across a sticky floor before leaving the nuclear power station?

Tick (✓) one box.

The places where people work and live contribute to the nuclear radiation they are exposed to.

Table 3 shows the mean daily dose of radiation caused by two different jobs.

Calculate the number of days a nuclear power station worker must work before receiving the same dose that an aeroplane pilot receives in one day.

The process of nuclear fission takes place in nuclear power stations.

The process of nuclear fusion takes place in the Sun.

Draw one line from each process to its fuel.

Some isotopes emit nuclear radiation.

Carbon-14 and carbon-12 are isotopes of carbon. Compare the structure of an atom of carbon-14 with the structure of an atom of carbon-12.

Carbon-14 is a radioactive isotope. Carbon-14 has a half-life of 5700 years. What does ‘a half-life of 5700 years’ mean?

Table 1 gives the half-life of some other radioactive isotopes.

A sample of fluorine-17 has an activity that is one quarter of its original activity. Calculate the age of the sample of fluorine-17.

All of the isotopes in Table 1 emit beta radiation. Explain which isotope would cause the biggest risk to a person’s health based only on the half-life of each isotope.

People who work in the nuclear power industry need to be aware of irradiation and contamination. Describe the difference between irradiation and contamination.

Give one health risk to a person working close to a source of nuclear radiation.

Workers in nuclear power stations are monitored to check the radiation they emit. A worker stands 1 cm away from a radiation detector. The amount of radiation the worker emits is recorded. Explain why the worker needs to stand close to the radiation detector.

Workers in the nuclear power industry are exposed to nuclear radiation. Pilots on aircraft are exposed to cosmic radiation from space. daily dose caused by working in a nuclear power station = 0.00050 mSv hourly dose from cosmic rays to a pilot while flying = 0.0030 mSv Calculate the number of days it takes for a nuclear power station worker to receive the same dose as a pilot flying for 24 hours.

Complete the nuclear equation for this decay by writing the missing number in each box.

Explain how the risk from internal contamination is different to the risk from external irradiation by a source of alpha radiation.

Radioactive waste from nuclear power stations is a man-made source of background radiation.

Which of the following is also a man-made source of background radiation? Tick (✓) one box.

Nuclear power stations use the process of nuclear fission. Complete the sentences to describe the process of nuclear fission. Choose answers from the box.

Plutonium-239 is one type of radioactive waste from nuclear power stations. The following nuclear equation represents the decay of plutonium-239 (Pu-239). 239 235 4

How does the nuclear equation show that alpha radiation is emitted when plutonium-239 decays?

Tick (✓) one box.

Figure 8 shows how the activity of a sample of plutonium-239 varies with time.

How much time will it take for the activity of the sample of plutonium-239 to fall to half of its initial activity?

What is the half-life of plutonium-239?

The radioactive waste from a nuclear power station is buried underground. People are warned to stay away from places where radioactive waste is buried. Suggest one risk of going near the place where radioactive waste is buried.

Polonium-210 is a radioactive isotope that decays by emitting alpha radiation.

Complete the decay equation for polonium-210

Explain why contamination of the inside of the human body by a radioactive material that emits alpha radiation is highly dangerous.

A sample of polonium-210 was left for 414 days.

After this time it had a mass of 1.45 × 10^-4 g

The half-life of polonium-210 is 138 days.

Calculate the initial mass of the sample.