Nuclear

Question 1

When heavy nuclei decay, which particle do they emit?

Answer 1

Alpha

Question 2

When light nuclei decay, which particle do they emit?

Answer 2

Beta-

Question 3

What is a metastable state?

Answer 3

Some nuclei can remain in an area excited state for a long period of time after decay, allowing for a pure gamma emitter to be produced.

Question 4

Define the relative atomic mass unit ‘u’.

Answer 4

1/12th the mass of a carbon atom.

Question 5

Define binding energy.

Answer 5

The energy required to completely separate the nucleus into its individual nucleons.

Question 6

Define mass defect.

Answer 6

The difference in mass between a nucleus and its constituent nucleons (which have more than the nucleus).

Question 7

Why does fission and fusion occur?

Answer 7

Energy is released which makes the new nuclei more stable (closer to iron 56).

Question 8

List the 4 components of a fission reactor and state their function.

Answer 8

• Control rods (boron): absorb neutrons without further fission occurring
• Moderator (graphite/ water): slows neutrons down to thermal speeds so they can be absorbed by uranium nuclei
• Coolant (heavy water/ CO₂): takes kinetic energy to water to make steam and turn turbine
• Fuel rods (uranium): undergo fission when they absorb a neutron

Question 9

How is nuclear waste dealt with?

Answer 9

1. Left to cool by putting materials in acid
2. Vitrified (encased in molten glass that hardens). Glass is non-porous
3. Buried deep underground, far away from water sources and tectonic fault lines, to minimise radiation exposure to organisms

Question 10

Why does the inverse square law graph curve at the end and not go through the origin?

Answer 10

• Curves when near the source due to alpha and beta emission
• Systematic error due to source and detector not being at the end of their casings