Fission and Fusion

Question 1

Describe the process of nuclear fission

Answer 1

A slow moving neutron is absorbed by a Uranium-235 nucleus, causing it to become Uranium-236 which is unstable. Due to how unstable it is, the isotope splits apart, decaying into Barium-144, Krypton-89, 3 neutrons and gamma radiation. These neutrons produced are then absorbed by other uranium nuclei, starting a chain reaction with further fissions occuring. This process releases a lot of energy, as a lot of mass is lost

Question 2

What are the products of nuclear fission

Answer 2

Barium-144
Krypton-89
3 neutrons
Gamma radiation

Question 3

How does a nuclear reactor work

Answer 3

In a nuclear reactor, neutrons are sent into nuclei of Uranium-235. These split up, giving out energy in the kinetic energy stores of the fission products. This kinetic energy is converted into thermal energy, which then turns water into steam. This steam can be used to drive turbines that generate electricity

Question 4

What does the moderator/blocks of graphite do in a nuclear reactor

Answer 4

The moderator is used to slow down neutrons so that they can be absorbed by uranium-235 nuclei, thus allowing for fission to occur

Question 5

What do the control rods in a nuclear reactor do

Answer 5

The control rods can be used to control the rate of fission as they have the ability to stop the neutrons by absorbing them or let them interact with nuclei more freely

Question 6

What is nuclear fusion

Answer 6

Nuclear fusion is a process in which two or more small nuclei combine to form one larger nucleus, releasing energy

Question 7

Describe the process of nuclear fusion

Answer 7

In nuclear fusion, the two isotopes of hydrogen, deuterium and tritium, fuse together forming a larger nucleus of helium, a neutron and gamma rays. Since the mass of deuterium and tritium is bigger than that of helium and the neutron, energy is released.

Question 8

What conditions are needed for fusion

Answer 8

In order for fusion to occur, the two nuclei have to come close together, something that’s made difficult by the strong electrostatic forces of repulsion between the nuclei. Therefore, the process can only occur under high temperature and pressure, so that the nuclei have enough kinetic energy to overcome the forces of repulsion. Also, high density is required so that there is large collision rate to sustain fusion