Radiation - Nuclear Fission and Fusion T3

Question 1

Fuel rods

Answer 1

Made of Uranium - 238 and enriched with Uranium 235. Release energy via fission.

Question 2

Moderator

Answer 2

Made of graphite, has fuel rods embedded into it. Purpose to slow down the neutrons released by fission as nucleus is more easily split by slow neutrons.

Question 3

Control rods

Answer 3

Usually made of boron, control the rate of production of energy. Boron rods absorb the neutrons so by lowering the control rods into the reactor the reaction can be slowed down.

Question 4

Cooling system

Answer 4

Needed to cool the reactor and transfer heat to boilers to generate electricity.

Question 5

Containment vessel

Answer 5

Made of thick concrete which acts as a shield and absorbs neutrons and other types of radiation.

Question 6

Nuclear Fission

Answer 6

Larger atoms split into two smaller atoms releasing energy.

Question 7

Nuclear Fusion

Answer 7

Where smaller atoms combine (fuse) to create larger atoms.

Question 8

Chain reaction

Answer 8

The entire nucleus splits into two large fragments called ‘daughter nuclei’. In addition to the ‘daughter’ products, two or three neutrons also explode out of the fission reaction and these can collide with other uranium nuclei to cause further fission reactions. This is known as a chain reaction.

Question 9

Advantages of nuclear power

Answer 9

Fossil fuels are running out, so nuclear power provides a convenient way of producing electricity.
• A nuclear power station needs very little fuel compared with a coal or oil-fired power station. A tonne of uranium gives as much energy as 25,000 tonnes of coal.
• Unlike fossil fuels, nuclear fuel does not release large quantities of greenhouse gases or sulphur dioxide (a cause of acid rain) into the atmosphere.
• A country may not want to be reliant on imports of fossil fuels. If a country has no fossil fuels of its own it might use nuclear power for security reasons.

Question 10

Disadvantages of nuclear power

Answer 10

• A serious accident in a nuclear power station is a major disaster. British nuclear reactors cannot blow up like a nuclear bomb but even a conventional explosion can possibly release tonnes of radioactive materials into the atmosphere. (The Chernobyl disaster was an example of a serious accident.)
• Nuclear power stations produce radioactive waste, some of which is very difficult to deal with. Nobody wants radioactive waste stored near them.
• After a few decades nuclear power stations themselves will have to be decommissioned.

Question 11

Radioactive waste

Answer 11

Nuclear power plants produce dangerous amounts of radioactive waste. Concerns with this include storage (long time to decay) and transportation.

Question 12

Positives of nuclear fusion compared to nuclear fission

Answer 12

Release more energy per kg of fuel.
Makes less radioactive emissions as many products are stable i.e. He
Use cleaner fuel, isotopes of hydrogen for example.

Question 13

Negatives of nuclear fusion compared to fission.

Answer 13

Requires extremely high temperatures and high pressures.

At these high temperatures hydrogen is a plasma not a gas.