Nuclear Physics

Question 1

State and explain the results of the scattering experiment (6 marks)

Answer 1

-Most alpha particles pass straight through
-Which supposed atom is composed of mainly open space (DONT AWARD LARGE SPACE BETWEEN ATOMS)
-Alpha prticles can be backscarred or scattered by more than 90 degrees which suggests,
They have collided with something more massive thasn themselves
They have been repelled by a concentrated pos charge
-Suggests a ‘solar system’ configuration
-Scattering of alpha particles close to 180 degrees implies the particles have not touched the surface but have come really close
-

Question 2

State what happens to a neutron that is incident on the moderator. (1 mark)

Answer 2

The neutron undergoes an elastic collision and bounces off with less kinetic energy

Question 3

State what happens to a neutron that is incident on a control rod (1 mark)

Answer 3

Neutron gets absorbed

Question 4

A slow-moving neutron is in collision with a nucleus of an atom of the fuel which
causes fission.
Describe what happens in the process. (3 marks)

Answer 4

• The atom absorbs the neutron
• In order to become more stable the nucleus splits forming two smaller NUCLEI
• Releasing several fast moving neutrons

Question 5

A thermal nuclear reactor produces radioactive waste.
State the source of this waste and discuss some of the problems faced in dealing
with the waste at various stages of its treatment.
Your answer should include:
• the main source of the most dangerous waste
• a brief outline of how waste is treated
• problems faced in dealing with the waste, with suggestions for overcoming
these problems.
(6 marks)

Answer 5

-The (highly radioactive/ most dangerous) waste are the fission fragments
from the fission of uranium-235 or from (spent) fuel rods
-The waste is initially placed in cooling ponds/water (close to the reactor
for a number of years)
-plutonium/uranium is separated to be recycled
-high level waste is vitrified/made solid into (pyrex) glass
-then placed in lead/concrete bunkers
-to be stored DEEP* underground
solving
-the waste is (initially) is very hot/generates heat so has to be placed in
water/cooling ponds (to remove the heat)
-the waste (initially) is highly radioactive and needs to be screened in
water/cooling ponds (to absorb the radiation)
-the waste (initially) is highly radioactive and needs to be remotely
handled (to avoid human contact with the waste).
-In liquid form the (high level) waste may leak hence the need to vitrify
(and barrel in steel)

Question 6

Mass Defect:

Answer 6

m = Z mp + Nmn – MCo

Question 7

State what is represented by gravitational field lines(1 mark)

Answer 7

Gravitational field lines show the direction of force on a mass