Revision forP6: Radioactive Materials

Learning Objective:• To review the key areas in

preparation for the P6 Exam.

Nuclear Radiation

• Comes from the nucleus• Nucleus contains neutrons and protons• Electrons orbit around the edge

NucleusElectrons

Two isotopes of Carbon – both have 6 protons but different numbers of neutrons.

3 Types of Radiation

Alpha• Very ionising• Not very penetrating• Absorbed by paper or dead skin cells• Stopped by only a few centimetres of air

Beta• Slightly ionising• Absorbed by aluminium or half a metre of air

Gamma• Not very ionising• Very penetrating• Absorbed by lead or thick concrete

Efficiency

• Efficiency, as a percentage, is worked out by:

• The more efficient the object is the less energy is wasted or dissipated in an wasteful way

• Be able to interpret energy flow diagrams

Useful energy outx100

Total energy in

Background Radiation

The dose of radiation is measured in sieverts Sv,

or millisieverts

mSv.

Contamination IrradiationThis is when the source is inside the body, or on your skin and will affect you all of the time.

This is when a source outside the body affects you – but only when you are near it.

What happens when radiation hits a cell?

Radiation passes straight

through

If it hits a sex cell it could

cause a mutation by changing a

gene

Damaged – but repairs itself

The DNA is damaged and the cell develops out of control – a cancer has

begun

It is killed

Energy Resources

Primary Energy Source:

• A source of energy not made from any other sort of energy source

• e.g. fossil fuels and uranium

Secondary Energy Source:

• A source of energy that can be distributed easily but has been manufactured using a primary energy source

• e.g. electricity

Renewable: Non-Renewable:Will not run oute.g. wind, solar, tides…

Fossil Fuels – will run out; release waste including carbon dioxide; e.g. coal, oil, gas

Nuclear Fuels – There are large amounts but not infinite, they release radioactive waste which has to be handled carefully; e.g. Uranium

Fossil Fuel Power Station

Be able to label a diagram like this

Nuclear Power Station

Know the differences between these 2 diagrams

Fission

Neutron

Chain ReactionUncontrolled – causes a nuclear bomb

Controlled – used in a power station

Half Life

The half life of a radioactive substance is the amount of time it takes for the activity (amount of

radiation that is given out) to fall to half the previous value.

3 Types of Waste

Low Level• e.g. protective clothing and medical equipment• Packed in drums and put in a special landfill site

Intermediate Level• Less dangerous that high level waste

High Level• E.g. spent/old fuel rods• This gets hot as it is so radioactive, it’s kept in a

pool of water to absorb the heat

Health and Radioactive Materials

Some questions will expect you to understand and / or discuss:

• ALARA• Risks and Benefit• Precautionary Principle• Perceived risk and Actual risk