Nuclear fission and fusion

What is nuclear fission?

• The splitting of an atom

• The joining of two light nuclei

• The induced splitting of a heavy nucleus

What is a chain reaction?

• A reaction that causes a chain made from uranium to split

• When atoms of uranium join together in a long chain

• When neutrons from one reaction fire off to cause further reactions

What particle is used to trigger the fission of a uranium nucleus?

• A neutron

• A proton

• An electron

How is the chain reaction slowed in a nuclear reactor?

• By removing the fuel rods

• By inserting the control rods

• By cooling the reactor down

Apart from uranium, which other element is commonly used as fuel in fission reactors?

• Plutonium

• Mercury

• Iron

• Nickel

Why is the reactor filled with graphite or water?

• To speed up the neutrons

• To slow down the neutrons

• To stop the neutrons

What is nuclear fusion?

• The splitting of an atom

• The joining of two light nuclei

• The splitting of a heavy nucleus

Where does fusion occur naturally?

• In bombs

• In stars

• In power stations

Why does fusion only happen at very high temperatures?

• Because it happens in stars

• To overcome the repulsion of the positives

• To increase the speed of the reaction

What is the job of the moderator?

• Absorb neutrons

• Speed up the reaction

• Cool the reactor

• Slow down the neutrons