- Chemotherapy
o Gamma emitters are used to emit gamma rays, which are directed onto certain
areas of the body with cancerous cells, which absorb the energy and die, controlling
the disease
o It is used to control any other unwanted tissue too
o However, as it is hard to direct accurately, surrounding healthy cells may also be
irradiated, and their destruction causes unhealthy side effects
Nuclear Fission (Physics only)
- Nuclear fission is the splitting of a large and unstable nucleus (eg uranium or plutonium).
- Spontaneous fission is rare. Usually, for fission to occur the unstable nucleus must first
absorb a neutron.
- When the unstable nuclei absorbs a neutron it splits into two smaller nuclei, roughly equal in
size and it then emits two or three neutrons and gamma rays.
- Energy is released by the fission reaction.
- This neutron may collide with another radioactive nucleus.
- This nucleus absorbs the neutron and becomes unstable
- This nucleus splits, releasing another neutron and produces more energy
- This is a chain reaction, as energy is being released and one ‘split’ causes another to occur
o A neutron needs to be absorbed initially before it splits, because it needs a little extra
energy before it can split and release lots of energy – like a ramp on a cliff, the
neutron gives it enough of a kick to get over the ramp to fall
- After the nucleus splits, it leaves two smaller nuclei roughly equal in size
- And they both (along with the neutrons) have kinetic energy
- If the chain reaction is not controlled, it will increase at an exponential rate – which is what
happens in a nuclear weapon
- This process is used in nuclear fission, with uranium nuclei
Nuclear Fusion (Physics only)
- This is when two small nuclei fuse to form a heavier nucleus, releasing (lots of) energy
- The sum of the masses of the two nuclei is more than the mass of the heavier nucleus
- Some of the mass is converted into energy. (released as radiation)
- The sun is a natural fusion reactor.
- Fusion would be a much more efficient way of producing energy compared to fission
however no design has been produced that could accomplish positive net energy on earth.