Nuclear Fission and Fusion

Question 1

What is |Fission?

Answer 1

The splitting of large, unstable nuclei to form smaller more stable nuclei (+the emotion of spare neutrons)

Question 2

Give an example of a fissionable isotope.

Answer 2

Uranium - 235

Question 3

What usually needed to happen to induce fission?

Answer 3

• The unstable nuclei must absorb a neutron

* Spontaneous fission (where no neutron absorption occurs) is rare

Question 4

Alongside 2 smaller nuclei, what else is emitted in a fission reaction?

Answer 4

• 2 or 3 neutrons
• Gamma rays
• Energy

Question 5

What forms of energy do all fission products have?

Answer 5

Kinetic energy

Question 6

What takes place during a chain reaction in a nuclear reactor?

Answer 6

• An unstable nucleus absorbs a neutron
• The nucleus undergoes fission and releases 2 or 3 further neutrons
• These induce more fission, which results in a chain reaction.

Question 7

What is the consequence of an uncontrolled chain reaction?

Answer 7

• The rate of fission events becomes to high and result in the production of too much energy
• This can lead to an nuclear explosion

Question 8

What are the 3 main components of a core nuclear reactor?

Answer 8

1. Fuel rods
2. control rods
3. Moderator

Question 9

What is the role of the moderator in a nuclear reactor?

Answer 9

To slow down the neutrons so they are travelling at speeds which allow than to be absorbed by fissile nuclei and cause fission.

Question 10

How is the chain reaction in fission reactor kept under control?

Answer 10

• Control rods are positioned in between the fuel rods
• The rate of fission is controlled by moving these rods up and down
• The lower the rods are inserted, the slower the rate of fussion.

Question 11

What is the term use to describe nuclei in which fission can be induced through the absorption of slow neutrons.

Answer 11

Fissile Nuclei

Question 12

What is nuclear fusion?

Answer 12

The joining of two light nuclei to produce a heavier nuclei and release energy.

Question 13

Name to isotopes if hydrogen which are commonly used in nuclear fusion.

Answer 13

Deuterium and Tritium

Question 14

Explain the difficulty of generation energy through nuclear fusion.

Answer 14

It requires very high temperatures, with in itself requires large quantities of energy and also requires casing which can withstand them.

Question 15

Explain why nuclear fusion is currently not a viable way to produce energy on earth.

Answer 15

With current equipment/techniques, the energy required is greater than the energy produced, resulting in a net loss.