Irradiation & contamination

The photograph shows a cloud chamber, used to observe alpha radiation produced by a radioactive source. The radioactive source is inside the cloud chamber, as shown in the photograph.

Describe the structure of an alpha particle.

The source used in the cloud chamber contains the isotope radium-226.

The incomplete nuclear equation shows the decay of radium-226 into an isotope of radon.

Complete the nuclear equation by writing the correct numbers in the boxes.

The tracks in the cloud chamber can be seen through the glass viewing window.

Explain why the radioactive source is not a hazard to the person viewing the cloud chamber.

When radiation is emitted from the source a white line is produced in the cloud chamber. The white line is known as a track.

The diagram shows the tracks produced by the radiation from the source.

The diameter of the cloud chamber is also shown.

Explain the properties of alpha radiation that can be deduced from the length of the tracks.

A protactinium generator is a device that can produce samples of an isotope called protactinium‑234m.

A teacher investigates the activity of protactinium‑234m using the apparatus shown in the photograph.

The teacher uses a radiation detector to detect the radiation emitted from the protactinium‑234m.

Give the name of a suitable radiation detector.

Give two safety precautions to minimise the risk of harm to the teacher from the radiation emitted by the protactinium generator.

Protactinium‑234m decays with a half‑life of 70 seconds.

The initial count rate is 840 counts per second.

Calculate the expected count rate after 140 seconds.

count rate =_........ counts per second

The activity of an isotope is the total amount of radiation emitted each second.

The teacher estimates that only 5% of the total radiation emitted is detected by the radiation detector.

Estimate the activity of the isotope when the count rate is 840 counts per second.

Give the unit.

The photograph shows the nuclear fusion reactor called ITER.

Describe the difference between nuclear fusion and nuclear fission.

At ITER, hydrogen-3 and hydrogen-2 will be fused into helium and another particle labelled X.

Complete the nuclear equation for the fusion of hydrogen-3 and hydrogen-2.

Discuss potential safety advantages of a fusion reactor compared with a fission reactor.

You should refer to the products of this fusion reaction and to the fission reaction of uranium.

The half-life of a radioactive isotope is 12 years.

The activity of a sample of this isotope is 120 kBq.

Calculate the activity of this sample after 48 years.

A teacher demonstrates the penetrating ability of alpha, beta and gamma radiation from some radioactive sources.

State a precaution the teacher should take to make sure they are working safely with the radioactive sources.

State the name of a detector the teacher could use to detect the radiation from each source.

Draw crosses () in the table to show which type of radiation cannot penetrate each material in the table.

An alpha particle of mass 6.610^–27kg travelling at a speed of 2.110⁷m/s hits a sheet of paper.

Calculate the kinetic energy (KE) of the alpha particle.

State the work done on the alpha particle when its speed is reduced to 0 m/s by the sheet of paper.

State which energy store of the paper increases when the alpha particle is stopped.

A material called granite is used as a work surface in a kitchen.

Granite is formed naturally and contains radioactive isotopes.

The granite work surface contributes to the background radiation in the kitchen.

Give another naturally occurring source of background radiation.

Granite contains the isotope thorium‑232 (²³²₉₀Th).

Thorium‑232 decays by a sequence of alpha decays and beta decays to form radon‑220 (²²⁰₈₆Rn).

State two differences between alpha radiation and beta radiation.

The incomplete nuclear decay equation summarises the decay sequence of thorium-232 into radon‑220.

Calculate the number of alpha particles and the number of beta particles emitted in this decay sequence.

Thorium‑232 is a solid and remains in the work surface.

Radon‑220 is a gas and is emitted from the work surface.

Thorium‑232 and radon‑220 both emit alpha radiation.

Discuss the hazards due to the granite work surface when a person is working in the kitchen.

Refer to contamination and irradiation in your answer.

Radon is a radioactive gas that contributes to background radiation.

Describe what is meant by the term background radiation.

The graph shows the activity of a sample of radon‑222.

State what is meant by the term half‑life.

Use the graph to determine the half‑life of radon‑222.

Radon‑222 is formed by multiple alpha decays of uranium‑234.

Complete the nuclear equation by giving the missing information.

Radon‑222 also emits alpha radiation.

Explain the hazard to humans of breathing in air contaminated with radon‑222.

Cobalt‑60 is a radioactive isotope of cobalt.

The table gives the activity of a sample of cobalt‑60 over a period of 10 years.

Give a suitable unit for activity.

The graph shows the data.

Label both axes.

Draw the curve of best fit.

Use the graph to determine the half‑life of cobalt‑60.

Estimate the time taken for the activity to decrease to of its initial value.

Cobalt‑60 decays by beta emission.

Describe what happens to the nucleus of a cobalt‑60 atom during beta decay.

Cobalt‑60 also emits gamma radiation.

Cobalt‑60 is produced in a nuclear reactor.

Discuss the hazards involved and the precautions taken when disposing of cobalt‑60.

A teacher uses a radioactive source containing atoms of the isotope radium-226.

Give a safety precaution that would reduce the teacher’s exposure to radiation when working with the radioactive source.

Radium-226 can be represented using the symbol

How many neutrons are in the nucleus of an atom of radium-226?

The teacher investigates the type of radiation emitted from the radioactive source.

Give the name of a piece of apparatus that detects ionising radiation.

The teacher finds that the radiation emitted from the radioactive source is not detected when the detector is more than 5 cm away from the source.

State the type of radiation emitted by the radioactive source.

The number of radium-226 atoms in the source decreases over time, with a half-life of 1600 years.

State what is meant by the term half-life.

The radioactive source contains 2.66 × 10²¹ atoms of radium-226.

Approximately how many atoms of radium-226 will remain in the source after 800 years?

Uranium-235 captures a neutron and undergoes nuclear fission in a chain reaction.

The equation shows a possible nuclear fission reaction.

Calculate x, the number of neutrons released by this fission reaction.

Describe what is meant by a chain reaction.

Iodine-129 is an isotope found in radioactive waste from nuclear power stations.

Iodine-129 has a half-life of approximately 15 million years.

A sample of iodine-129 has an activity of 72 kBq.

Show that the time required for the sample to have an activity less than 5 kBq is approximately 60 million years.

Some radioactive waste from nuclear power stations has a very long half-life.

Discuss precautions that must be taken when disposing of this radioactive waste.

An aircraft travels along a runway.

The aircraft starts from rest and has a constant acceleration of 4.1 m/s².

Calculate the distance required to reach take‑off speed of 75 m/s.

The aircraft takes off and reaches its maximum height above the ground.

At maximum height, the background radiation count rate is higher than on the ground.

Explain what is meant by background radiation.

Suggest why there is a limit to the number of hours that an airline pilot can fly at maximum height.

Technetium-98 and technetium-99 are isotopes of the element technetium.

Describe the difference between the nuclei of technetium-98 and technetium-99

Technetium-99 is formed when the element molybdenum-99 decays.

Complete the nuclear equation for the decay of molybdenum into technetium-99

Describe an experiment that a scientist could use to demonstrate that the emission from technetium-99 is gamma radiation.

Include details of a safety precaution in your answer.

A scientist measures the count rate at different distances from the technetium source.

The graph shows how the count rate changes with distance from the technetium source.

The scientist suggests that the relationship between the count rate and distance is (distance)² × count rate constant

Use data from the graph to determine whether these results support this relationship.

Technetium-99m is an isotope of the element technetium.

Technetium-99m has a half-life of 6 hours.

A sample of technetium-99m has an initial activity of 160 Bq.

Complete the graph to show how the activity of this sample of technetium-99m changes over a period of 24 hours.

Technetium-99m has a half-life of 6 hours and can be used as a medical tracer.

It is injected into a patient’s blood and moves around the patient’s body.

Technetium-99m emits gamma radiation, which is used to locate the position of the tracer in the patient’s body.

Technetium-99m does not exist naturally.

Suggest why technetium-99m is usually made at the hospital where it is used.

Explain why technetium-99m is an effective isotope to use as a medical tracer.

The gamma radiation emitted by technetium-99m is potentially harmful to humans.

Discuss the risks of using technetium-99m to doctors and to patients.

Some of the energy stored in the nuclei of atoms can be used to generate electricity.

A nuclear fission power station generates electricity.

State the role of the moderator in a nuclear fission power station.

Some of the daughter nuclei produced in nuclear fission are highly radioactive and emit high energy neutrons when they decay.

Explain which feature of a nuclear fission reactor reduces the risks from these high energy neutrons.

The daughter nuclei can cause contamination and irradiation.

Describe the difference between contamination and irradiation.

Nuclear fusion is another process that could be used to generate electricity.

Describe the process of nuclear fusion.

State where nuclear fusion occurs naturally.

Generating electricity from nuclear fusion is very difficult as the conditions needed are hard to achieve and maintain.

Explain the conditions required for nuclear fusion.

The radiation kills bacteria on the fruit. 9