1. Cornwall, Devon, Wales, Cumbria, Granite
Radon Gas (Granite)
Ground and buildings
Medical sources
Food and drink
Cosmic rays
Nuclear power & weapons

2. α ɣ ɣ ɣ it is absorbed by smoke particles
Food is sealed so no microbes can enter the packaging. It is then exposed to a high dose of gamma radiation, sufficient to kill any microbes present.
Alpha radiation is emitted from the Americium source. The Alpha radiation ionises the air in the gap between the plates.
The ionised air allows current to flow between the plates.
When smoke particles are present, they absorb the alpha particles, so ionisation of the air does not occur, so the current stops. When the current stops, an alarm is triggered. ɣ
it will penetrate through to all of the food. ɣ
it will penetrate through to all of the equipment. ɣ
it will penetrate through the ground and be detected.
Surgical equipment is sealed so no microbes can enter the packaging. It is then exposed to a high dose of gamma radiation, sufficient to kill any microbes present.
A gamma emitter is placed into the water. Where a leak occurs, water collects, so more gamma radiation will be detected above ground.
The gamma emitter should have a fairly short half-life.

3. β
it will partially penetrate the steel, so penetration will depend on the thickness of the steel
Beta radiation is emitted below the steel, and detected above the steel. If the steel is too thin, not a lot of beta radiation will be absorbed, and so a lot will reach the detector. If the detector detects a high level of beta radiation, the computer will reduce the pressure pushing the rollers together.
If the steel is too thick, too much beta radiation will be absorbed, so not a lot will reach the detector. If the detector detects a low level of beta radiation, the computer will increase the pressure pushing the rollers together.

4. ɣ ɣ it will penetrate out of the body to the detector
it will penetrate through the body to the tumour
A small amount of gamma emitter chemically attached to glucose is injected into the patient’s blood stream. Areas where there is high metabolic activity, including where a cancerous tumour is present, will absorb more of the glucose, so also more of the emitter.
A gamma detector detects the amount of gamma radiation coming from different areas of the body, so a picture is built up with this information, showing areas where cancer may be present.
Gamma radiation is targeted at the tumour from various different directions. Each beam of gamma rays is a relatively low dose, so this minimises the risk of secondary cancer/cell damage being caused by the gamma radiation as it travels through healthy tissue.
The tumour receives a low dose from each beam, which add up to a high dose which kills the cells.

5. So, the count rate after 500 days is 1/32 of the original count rate:
Half life is the time it takes for half of the radioisotope’s atoms to decay (emit alpha, beta or gamma radiation). So, after 1 half life (100 days in the case of the radioisotope in 6.4) the number of radioactive atoms has halved, so the count rate will halve. In this case, the count rate has reduced from 800Bq to 400Bq.
In another 100 days (one more half life) the count rate will halve again, from 400Bq to 200Bq.
800Bq
400Bq
Each half life (100 days) the count rate halves, so in 500 days the count rate has halved 5 times as 5 half-lives have passed.
½ x ½ x ½ x ½ x ½ = 1/32
So, the count rate after 500 days is 1/32 of the original count rate:
800/32 = 25Bq
200Bq
100Bq
100 days
200 days
300 days

6. It takes two half lives to get to this stage ( ½ x ½ = ¼ )
For every 4 particles, 3 are Lead 206 and one is Uranium 238. This means that only ¼ of the atoms are still Uranium 238.
It takes two half lives to get to this stage ( ½ x ½ = ¼ )
so the rock must be 2x4.9x109 =9.8x109 years old
Dice are thrown, and any which land on a 6 represent an atom which has decayed, so are taken out of the sample. The remaining dice represent atoms which are still radioactive. The radioactive ones are then thrown again, and a note is taken of how many remain at each throw.
The number of radioactive atoms determines the rate of decay. If 60 remain in our dice model, the chances are that 10 will decay in the next throw. If 6 remain, the chances are that 1 will decay in the next throw.
Similarly in a radioisotope, a greater number of atoms which remain radioactive results in a greater rate of decay, hence radiation emission.

7. Handled material with bare hands
Ionising radiation transfers energy to electrons in atoms, causing them to be ejected from the atom, forming an ion (a charged atom). Ions are more reactive than their atoms, so when this happens near the DNA, the DNA sequence can be altered. In most cases this is harmless, however sometimes this causes the cell to reproduce in an uncontrolled way. This is cancer.
Professionals will wear protective clothing to prevent radioactive material coming into contact with them. If this were to happen, the material would continue to emit radiation near their body and deliver a large dose over time. Professionals will often stand behind shielding, often made of thick lead, which will absorb most of the radiation. Where radiation levels are very high, remotely controlled robotics will be used so humans do not go near the areas with extremely high doses of radiation. A badge will be worn which changes colour when a certain dose of radiation has been exceeded so the professional knows when to remove themselves from the radiation source.
Handled material with bare hands
Handle material using tongs or robotic arms
Experimented in close proximity to radioactive materials
Experiment from behind appropriate shielding
Put radioactive materials in their pockets
Store radioactive material in lead lined containers
Pointed radioactive sources anywhere
Point radioactive sources away from people
Allowed frequent contact with skin
Wear full body protective suits and wash down in decontamination facilities to prevent radioactive material remaining on skin.
Modern scientists are aware of the effects of ionising radiation on human cells, including cancer (where ionisation causes mutations) and radiation sickness (where ionisation kills the cells).
Marie Curie died of Leukemia (cancer of the blood cells). This can be caused by exposure to ionising radiation.

8. Concrete degrades long before many radioisotopes decay to safe levels of emissions. Water can leak into the bunker and dissolve material which will contaminate the water table.
Possibility of contamination can be minimised through maintenance. The environment is shielded from the ionising radiation by thick lead-lined walls
Burial on land
This requires no maintenance and there are many locations available. Once dissolved, the concentration of radioisotopes in the oceans is small due to the vast quantity of water.
Water quickly dissolves the radioisotopes and these enter the food chain. Radioisotopes bio-accumulate so the fish we catch and eat may contain a high concentration of radioisotope.
Dumping at sea
Reprocessing
This reduces the amount of radioactive material destined for disposal and prevents the need for mining of new material.
Not all radioactive materials can be reprocessed, and in the process there is an increased risk of exposure of the workforce to ionising radiation.

9. Nuclear power stations do not release carbon dioxide (greenhouse gas) or sulphur dioxide (cause of acid rain) once built. They generate a very large amount of electricity in a reliable and predictable way. Only a small amount of fuel is required and only a small amount of waste is produced.
Whilst it is not a renewable resource, uranium supplies will not run out in the near future, whereas coal reserves are set to run out in around a hundred years’ time.
Coal power stations also provide a large reliable source of electricity, however they do so without producing any radioactive waste which is expensive and difficult to reliably store / reprocess. Coal power stations are not at risk of nuclear explosion, and are much easier to control and so are at a very low risk of a steam explosion. Even if such an explosion were to occur, unlike a nuclear power station where highly radioactive materials would enter the atmosphere and affect hundreds of thousands of people, the only casualties involved in a coal power station explosion would be those who work in the power station.
The public perception of nuclear is focused on how the worst-case scenario would affect them, however the lack of carbon dioxide emissions once build, along with the sustainable nature of the fuel source provide nuclear power with a clear advantage over coal power as a long-term option.
(A pro-coal conclusion would be equally valid – this is only an example!)