Learning Objective:
•To review the key areas in
preparation for the P3 Exam.
Thursday, 24 March
2016
Revision for
P3: Radioactive Materials
Nuclear Radiation
• Comes from the nucleus
• Nucleus contains neutrons and protons
• Electrons orbit around the edge
Electrons
Nucleus
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:
Useful energy out
Total energy in
x100
• The more efficient the object is the less energy is
wasted or dissipated in an wasteful way
• Be able to interpret energy flow diagrams
Background Radiation
The dose of
radiation is
measured in
sieverts Sv,
or
millisieverts
mSv.
Contamination
Irradiation
This 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.
Radiation
passes straight
through
Damaged – but
repairs itself
What happens when
radiation hits a cell?
If it hits a sex
cell it could
cause a
mutation by
changing a
gene
It is killed
The DNA is damaged and
the cell develops out of
control – a cancer has
begun
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:
Will not run out
e.g. wind, solar, tides…
Non-Renewable:
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 Reaction
Uncontrolled – 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