Radioactivity and particles

Question 1

Describe what is meant by nuclear fission (2 marks)

Answer 1

• Nucleus / nuclei splitting apart
• Releasing daughter nuclei

Question 2

Describe the process of nuclear fusion (2 marks)

Answer 2

• Creation of a large nucleus from small nuclei
• Resulting in the loss of mass and the release of energy

Question 3

What are the conditions required for nuclear fusion? (3 marks)

Answer 3

• High temperature required to increase kinetic energy
• High pressure required to bring nuclei close enough to collide
• As nuclei repel each other

Question 4

Describe What is Meant By A Chain Reaction (3 marks)

Answer 4

• Nuclear fission releases neutrons
• These neutrons can be captured by other nuclei
• These nuclei can then undergo fission

Question 5

What is the difference between contamination and irradiation (2 marks)

Answer 5

• Contamination is when a non-radioactive object comes into contact with radioactive material
• Irradiation is when radiation is present

Question 6

What is ionisation? (2 marks)

Answer 6

The process by which an atom becomes negatively or positively charged by the addition or removal of an electron.

Question 7

What instrument detects and measures radiation? (1 mark)

Answer 7

• Geiger-Muller tube

Question 8

Give two sources of background radiation (2 marks)

Answer 8

• Cosmic rays
• Rocks which give off radon gas

Question 9

What does a moderator in a nuclear reactor do and what is it made from? (2 marks)

Answer 9

• It slows down the neutrons
• Usually made from graphite

Question 10

What do the control rods do in a nuclear reactor and what are they made from? (2 marks)

Answer 10

• Control rods limit the rate of fission by absorbing excess neutrons
• Control rods are usually made from boron

Question 11

Why do nuclear reactors have shielding and what is it made from? (2 marks)

Answer 11

• Shielding is used to absorb the ionising radiation
• The shielding is usually thick concrete which may also contain lead

Question 12

What is the fuel in a nuclear reactor? (1 mark)

Answer 12

• The fuel is Uranium 235

Question 13

Discuss precautions when disposing of Nuclear Power radioactive waste (5 marks)

Answer 13

• Radioactive waste needs to be sealed in strong containers
• These containers must be made of a material which does not rust
• This means the containers are expensive and difficult to manufacture
• The containers are normally buried deep underground
• The site for burial must be secure and away from volcanic and tectonic activity
• The geology of the site must ensure that any radioactivity cannot leak into the water table

Question 14

Describe the problems that arise from the disposal of waste such as uranium from a nuclear power station (4 marks)

Answer 14

• The uranium will continue to be radioactive
• The uranium will still have high activity
• Uranium has a long half life so needs to be stored long term
• Danger to people and the environment
• Expensive as there is a need for shielding, burial and security

Question 15

What are the advantages and disadvantages of nuclear power generation

Answer 15

• Nuclear power plants don’t produce any greenhouse gases – Advantage
• Nuclear power plants provide a reliable electricity output e.g., not dependant on the weather – Advantage
• The amount of Uranium 235 available on earth is high so it wont run out for a very long time – Advantage
• Fuel such as uranium 235 is high density so a small amount provides a lot of energy - Advantage
• Nuclear power plants are expensive to build, maintain and decommission – Disadvantage
• Potential for a nuclear accident – Disadvantage
• High security risk - Disadvantage
• Waste products are radioactive, therefore very difficult to dispose of