TITLE: Ionising Radiation Assignment Task 2a/b

Objectives (We are learning that):• Describe the different types of ionising radiation.

(PASS)• Describe the problems associated with the use of

radioactive isotopes. (PASS)• Compare the benefits and drawbacks of using

radioactive isotopes in the home or workplace. (MERIT)

KEY WORDS:

RadiationAlphaBeta

GammaAtom

Nuclear model

Half lifeIsotope

Outcomes:You should be able to...

•Research a starter activity on Alexander Litvinyenko•Complete a summary table/poster of the uses of radioactive isotopes in industry and medicine•Create a flow diagram of how a nuclear power station works using slide 3•Watch a video/animation on nuclear fission and draw a poster of what is happening or a model including a chain reaction – slide 5 and 6

Nuclear fission occurs when a stable isotope is struck by a neutron. The isotope absorbs the neutron, becomes unstable and then splits apart, releasing large amounts of energy.

What is nuclear fission?

The fission of 1 kilogram of uranium-235 releases more energy than burning 2 million kilograms of coal!

Isotopes that undergo fission include uranium-235 and plutonium-239. These isotopes can both be used in nuclear reactors and in nuclear weapons.

How does nuclear power work?

For nuclear fission to start in a reactor, a uranium-235 atom must absorb a low speed neutron. High speed neutrons are not as readily absorbed by uranium nuclei.

Inside a nuclear reactor.

However, high speed neutrons are released during fission.

control rod

fuel rod

graphite core

water carrying away heat

The reactor’s graphite core slows down the released neutrons so the chain reaction can keep going.

Control rods made of boron absorb excess neutrons to prevent chain reactions getting out of control.

Nuclear fission results in a chain reaction because each time a nucleus splits it releases more neutrons, which can go on and cause more fission reactions to occur... and so on.

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This is why a chain reaction releases a lot of energy so rapidly.

If a chain reaction is uncontrolled, heat builds up very quickly. A chain reaction must be controlled to maintain a steady output of heat.

What are the stages of a chain reaction?

Nuclear fusion is the process which powers the Sun and other stars.What is nuclear fusion?

A worldwide research programme is being carried out to find ways in which nuclear fusion could be harnessed on Earth as a clean and plentiful source of energy.

In this process, small nuclei join together to form larger nuclei and energy is released.

In the Sun’s core, at temperatures of 15 million °C, hydrogen nuclei fuse to form helium nuclei and release vast amounts of energy.

What happens in nuclear fusion?

There are many advantages of using fusion energy:Why use nuclear fusion?

Abundant fuels – Deuterium can be extracted from water and tritium is made from lithium, which is readily available.

Clean – No greenhouse or other polluting gases are made.

No weapons material produced – The products are not suitable for making nuclear weapons.

Safe – No need to keep chain reactions under control.

Less radioactive waste – The products of nuclear fusion are not radioactive, although the reactor walls will absorb neutrons and become radioactive.

Small amounts of fuel – 10 grams of deuterium and 15 grams of tritium could produce enough energy for the lifetime of an average person in an industrialized country.

chain reaction – A self-sustaining series of reactions in which the neutrons produced in one fission cause more fission reactions to occur.

control rods – Tubes of material that absorb neutrons and are used to control chain reactions in a fission reactor.

daughter nuclei – The smaller nuclei formed by the fission of a larger nucleus.

fuel rods – Enriched uranium rods that are used to fuel nuclear fission reactors.

nuclear fission – The splitting of a large nucleus, which creates two smaller nuclei and releases a lot of energy.

nuclear fusion – The joining of two smaller nuclei, which makes a larger nucleus and releases a lot of energy.

Glossary