Chapter 13 - Nuclear Physics

Question 1

Define induced nuclear fission? (And why?)

Answer 1

A fission reaction started when the neutron is absorbed by the nucleus.

This happens because the neutron being absorbed makes it even more unstable so it splits.

Question 2

Define nuclear fusion?

Answer 2

A nuclear reaction where two light nuclei joined together to form a heavier but more stable nucleus.

Question 3

Write down examples for equations for nuclear fission and nuclear fusion?

Answer 3

Notes.

Question 4

Why is fusion so difficult to do?

Answer 4

Because high energy and pressure are required to overcome electrostatic repulsion between nuclei so that they confuse.

Question 5

Why is the mass of the nucleus less than the total mass of its components?

Answer 5

Because to pull the nucleus apart energy is used. Energy is lost, mass is gained, therefore we know that ‘the total mass and energy in a system remains constant’.

Question 6

What is greater the mass of the nucleus of the total mass of its components?

Answer 6

The mass of its components.

Question 7

Define mass defect?

Answer 7

The difference between the total mass of the individual, separate nucleons and the mass of the nucleus.

Question 8

Define binding energy?

Answer 8

The minimum external energy required to separate all the neutrons and protons of a nucleus.

Question 9

Binding energy equation?

Answer 9

Binding energy per nucleon

= total binding energy/nucleon number

Question 10

Describe and explain the binding energy against nucleon number graph?

Answer 10

Notes

Question 11

State four advantages of nuclear power?

Answer 11

• doesn’t produce co2
• uses small amount of fuel
• produces lots of energy
• very efficient

Question 12

State five disadvantages of nuclear power?

Answer 12

• produces hazardous waste
• releases lots of co2 making the power stations
• high risk
• people don’t want to live near them
• uranium expected to run out 30-60years time

Question 13

Name three fissile materials?

Answer 13

Uranium plutonium thorium

Question 14

Define chain reaction?

Answer 14

An exponential growth of a fission reaction caused by the increasing flux of neutrons causing fission.

Question 15

Explain three steps of induced fission?

Answer 15

1) One neutron strikes a uranium nucleus.
2) The neutron is absorbed creating a larger, unstable nucleus.
3) The highly unstable nucleus splits into two unequal parts and a number of neutrons.

Question 16

Explain the five steps in a fission reactor?

Answer 16

1) Uranium fuel releases energy
2) Core heats up and heats coolant
3) Coolant heats water to steam
4) Steam turns turbine
5) Turbine turns generator therefore produces electricity

Question 17

Look at fission reactor diagrams?

Answer 17

Notes

Question 18

Define coolant?

Answer 18

A substance used to transfer thermal energy from the core of the nuclear reactor.

Question 19

Define moderator?

Answer 19

The material used in a nuclear reactor to slow down fast moving neutrons so that they have a greater chance of interacting with the fissile material (eg. Graphite).

Question 20

Define control rods?

Answer 20

Rods of a neutron-absorbing material used to reduce the rate of a nuclear chain reaction (eg. Boron).

Question 21

Why do we get nuclear waste after nuclear fission?

Answer 21

After the reaction fuel rods contain fission fragments, making them highly radioactive.

Question 22

How are fast decaying and slow decaying nuclear waste dealt with?

Answer 22

Fast decaying - cooled for months

Slow decaying - buried in containers made of very thick cement

Question 23

Define nuclear fission?

Answer 23

The splitting of the nucleus into two large fragments and a small number of neutrons.