1. PHYSICS REVIEW
HOW DOES A FOSSIL FUELLED POWER STATION GENERATE ELECTRICITY? 3 5 4 1 2 6
Power station image - 7
Identify key parts of the Power Station. Also what does each part do?

2. HOW IS THIS DIFFERENT TO FOSSIL FUEL POWER STATIONS?
NUCLEAR POWER
Nuclear power uses radioactive ‘rods’ which are very hot to produce steam which turns the turbines.
NUCLEAR SYMBOL -
NUCLEAR POWER CARTOON IAMGE -
NUCLEAR POWER GIF -
HOW IS THIS DIFFERENT TO FOSSIL FUEL POWER STATIONS?

3. Learning objectives
State and explain what is meant by Nuclear Fission. (D)
State the isotopes commonly used in Nuclear Power stations. (C)
Explain the process of a nuclear fission chain reaction. (B)
Identify and explain in detail the key features of a Nuclear Power station. (A)
Keywords:
Proton Ion
Neutron Isotope
Electron Mass number
Charge Atomic Number
NOTICES: …………….

4. Nuclear Fission
Nuclear Fission is the splitting of an atomic nucleus. When this happens a lot of energy is released.
How is Nuclear Fission useful?
How is Nuclear Fission potentially dangerous?
The now even more unstable isotope splits to become more stable
A neutron is fired into a large nucleus
Releasing energy and high speed neutrons as it does so.
Fission means ‘to split’ or ‘divide’

5. Nuclear Fission – Chain Reaction
When a nucleus undergoes fission it:
Releases 2-3 neutrons at high speed.
Energy, in the form of radiation.
CHAIN REACTION
The release of high speed neutrons can go onto cause the fission of further nuclei, these split nuclei will then also release more high speed neutrons which will cause fission of other nuclei…..and so on….so on….

6. Nuclear Fission – Chain Reaction
During fission neutrons fired from a nucleus can go onto cause further fission resulting in a ‘chain reaction’

7. Inside a Nuclear Reactor
A Nuclear reactor contains nuclear fuel rods spaced evenly in the reactor core.
Water at high pressure flows through the reactor to exchange the heat energy to system. The water also acts a moderator as it slows down some neutrons
by absorbing them.
Control Rods
Fuel Rods

8. Inside a Nuclear Reactor - Fuel Rods
Uranium 235 and plutonium-239 are commonly used in Nuclear Reactors.
The reactor must contain fissionable isotopes. Typically a Uranium reactor would contain 2-3% fissionable uranium-235, therefore containing mostly non-fissionable uranium (uranium-239).
Why not use 100% fissionable uranium-235?

9. Inside a Nuclear Reactor - Control Rods
Control rods absorb surplus neutrons, to keep the chain reaction under control.
Why does the chain reaction need controlling?
‘Watch the simulation’
The depth the control rods are placed into the reactor allows control over the rate of the chain reaction.
This must be carefully managed to sustain a steady reaction.

10. Inside a Nuclear Reactor - Reactor Core
The reactor core is made of thick steel and enclosed in thick concrete walls.
Why are these materials used and why are they so thick?
The thick steel is able to withstand the high temperatures and pressures in the reactor.
The thick conrete walls absorb any radiation that escapes the reactor core.

11. Exam Questions Uranium-235 is used as a fuel in some nuclear reactors.
Name one other substance used as a fuel in some nuclear reactors.
……………………………………………………………………………….. (1)
Uranium-239 (Pu or thorium)
Energy is released from nuclear fuels by the process of nuclear fission. This energy is used to generate electricity. Describe how this energy is used to generate electricity. (Do not explain the fission process). …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………(3)
AQA
Energy used to heat water (1)
Produces high pressure steam (1)
Steam drives a turbine (turns a generator)

12. Exam Questions
Complete the diagram to show how the fission process starts a chain reaction. (2)
Diagram to show neutrons hitting othet U-235 isotopes. (1)
U-235 splitting to produce 2 or more neutrons. (1)
Xe-140
Neutron
U-235
AQA
Sr-94

13. Exam Questions
The control rods absorb neutrons without undergoing nuclear fission. Why does lowering the control rods reduce the amount of energy released each second from the nuclear fuel? (2)
Accept two from:
Control rods absorbe neutrons.
Fewer neutrons.
Chain reaction slows down.
AQA